Update README.md

Refactor authentication code; add OIDC support
Allow adding extra flags to LaTeX compiler through environment variable
2026-11-14 14:13:43 +01:00 · 2025-01-30 13:23:32 +01:00 · 2025-01-27 05:16:26 +01:00 · 2025-01-26 15:53:38 +01:00 · 2025-01-26 15:53:38 +01:00 · 2025-01-26 15:53:38 +01:00
1673 changed files with 57071 additions and 143585 deletions
@@ -14,6 +14,8 @@ When submitting an issue please describe the issue as clearly as possible, inclu
 reproduce the bug, which situations it appears in, what you expected to happen, and what actually happens.
 If you can include a screenshot for front end issues that is very helpful.

+**Note**: If you are using [www.overleaf.com](www.overleaf.com) and have a problem, or if you would like to request a new feature, please contact the Support team at support@overleaf.com. Raise an issue here only to report bugs in the Community Edition release of Overleaf.
+
 Pull Requests
 -------------

@@ -34,7 +36,7 @@ Please see [our security policy](https://github.com/overleaf/overleaf/security/p
 Contributor License Agreement
 -----------------------------

-Before we can accept any contributions of code, we need you to agree to our 
+Before we can accept any contributions of code, we need you to agree to our
 [Contributor License Agreement](https://docs.google.com/forms/d/e/1FAIpQLSef79XH3mb7yIiMzZw-yALEegS-wyFetvjTiNBfZvf_IHD2KA/viewform?usp=sf_link).
 This is to ensure that you own the copyright of your contribution, and that you
 agree to give us a license to use it in both the open source version, and the version
@@ -14,30 +14,866 @@
  <a href="#license">License</a>
 </p>

-<img src="doc/screenshot.png" alt="A screenshot of a project being edited in Overleaf Community Edition">
+<img src="doc/screenshot.png" alt="A screenshot of a project being edited in Overleaf Extended Community Edition">
 <p align="center">
-  Figure 1: A screenshot of a project being edited in Overleaf Community Edition.
+  Figure 1: A screenshot of a project being edited in Overleaf Extended Community Edition.
 </p>

 ## Community Edition

-[Overleaf](https://www.overleaf.com) is an open-source online real-time collaborative LaTeX editor. We run a hosted version at [www.overleaf.com](https://www.overleaf.com), but you can also run your own local version, and contribute to the development of Overleaf.
+[Overleaf](https://www.overleaf.com) is an open-source online real-time collaborative LaTeX editor. Overleaf runs a hosted version at [www.overleaf.com](https://www.overleaf.com), but you can also run your own local version, and contribute to the development of Overleaf.
+
+## Extended Community Edition
+
+The present "extended" version of Overleaf CE includes:
+
+- Sandboxed Compiles with TeX Live image selection
+- LDAP authentication
+- SAML authentication
+- OpenID Connect authentication
+- Real-time track changes and comments
+- Autocomplete of reference keys
+- Symbol Palette

 ## Enterprise

-If you want help installing and maintaining Overleaf in your lab or workplace, we offer an officially supported version called [Overleaf Server Pro](https://www.overleaf.com/for/enterprises). It also includes more features for security (SSO with LDAP or SAML), administration and collaboration (e.g. tracked changes). [Find out more!](https://www.overleaf.com/for/enterprises)
-
-## Keeping up to date
-
-Sign up to the [mailing list](https://mailchi.mp/overleaf.com/community-edition-and-server-pro) to get updates on Overleaf releases and development.
+If you want help installing and maintaining Overleaf in your lab or workplace, Overleaf offers an officially supported version called [Overleaf Server Pro](https://www.overleaf.com/for/enterprises).

 ## Installation

-We have detailed installation instructions in the [Overleaf Toolkit](https://github.com/overleaf/toolkit/).
+Detailed installation instructions can be found in the [Overleaf Toolkit](https://github.com/overleaf/toolkit/).
+To run a custom image, add a file named docker-compose.override.yml with the following or similar content into the `overleaf-toolkit/config directory`:

-## Upgrading
+```yml
+---
+version: '2.2'
+services:
+    sharelatex:
+        image: sharelatex/sharelatex:ext-ce
+        volumes:
+          - ../config/certs:/overleaf/certs
+```
+Here, the attached volume provides convenient access for the container to the certificates needed for SAML or LDAP authentication.

-If you are upgrading from a previous version of Overleaf, please see the [Release Notes section on the Wiki](https://github.com/overleaf/overleaf/wiki#release-notes) for all of the versions between your current version and the version you are upgrading to.
+If you want to build a Docker image of the extended CE based on the upstream v5.3.1 codebase, you can check out the corresponding tag by running:
+```
+git checkout v5.3.1-ext-v1
+```
+After building the image, switch to the latest state of the repository and check the `server-ce/hotfix` directory. If a subdirectory matching your version (e.g., `5.3.1`) exists, build a patched image.
+Alternatively, you can download a prebuilt image from Docker Hub:
+```
+docker pull overleafcep/sharelatex:5.3.1-ext-v1
+```
+Make sure to update the image name in overleaf-toolkit/config/docker-compose.override.yml accordingly.
+
+## Sandboxed Compiles
+
+To enable sandboxed compiles (also known as "Sibling containers"), set the following configuration options in `overleaf-toolkit/config/overleaf.rc`:
+
+```
+SERVER_PRO=true
+SIBLING_CONTAINERS_ENABLED=true
+```
+
+The following environment variables are used to specify which TeX Live images to use for sandboxed compiles:
+
+- `ALL_TEX_LIVE_DOCKER_IMAGES` **(required)**
+    * A comma-separated list of TeX Live images to use. These images will be downloaded or updated.
+      To skip downloading the images, set `SIBLING_CONTAINERS_PULL=false` in `config/overleaf.rc`.
+- `ALL_TEX_LIVE_DOCKER_IMAGE_NAMES`
+    * A comma-separated list of friendly names for the images. If omitted, the version name will be used (e.g., `latest-full`).
+- `TEX_LIVE_DOCKER_IMAGE` **(required)**
+    * The default TeX Live image that will be used for compiling new projects. The environment variable `ALL_TEX_LIVE_DOCKER_IMAGES` must include this image.
+
+Users can select the image for their project in the project menu.
+
+Here is an example where the default TeX Live image is `latest-full` from Docker Hub, but the `TL2023-historic` image can be used for older projects:
+```
+ALL_TEX_LIVE_DOCKER_IMAGES=texlive/texlive:latest-full, texlive/texlive:TL2023-historic
+ALL_TEX_LIVE_DOCKER_IMAGE_NAMES=TeXLive 2024, TeXLive 2023
+TEX_LIVE_DOCKER_IMAGE=texlive/texlive:latest-full
+```
+For additional details refer to
+[Server Pro: Sandboxed Compiles](https://github.com/overleaf/overleaf/wiki/Server-Pro:-Sandboxed-Compiles) and
+[Toolkit: Sandboxed Compiles](https://github.com/overleaf/toolkit/blob/master/doc/sandboxed-compiles.md).
+
+When the compilation takes place in a dedicated container, it is relatively safe to permit running external commands from inside the TeX
+file during compilation. This is required for packages like `minted`. For this purpose, the following environment variable can be used:
+
+- `TEX_COMPILER_EXTRA_FLAGS`
+    * A list of extra flags for TeX compiler. Example: `-shell-escape -file-line-error`
+
+<details>
+<summary><h4>Sample variables.env file</h4></summary>
+
+```
+OVERLEAF_APP_NAME="Our Overleaf Instance"
+
+ENABLED_LINKED_FILE_TYPES=project_file,project_output_file
+
+# Enables Thumbnail generation using ImageMagick
+ENABLE_CONVERSIONS=true
+
+# Disables email confirmation requirement
+EMAIL_CONFIRMATION_DISABLED=true
+
+## Nginx
+# NGINX_WORKER_PROCESSES=4
+# NGINX_WORKER_CONNECTIONS=768
+
+## Set for TLS via nginx-proxy
+# OVERLEAF_BEHIND_PROXY=true
+# OVERLEAF_SECURE_COOKIE=true
+
+OVERLEAF_SITE_URL=http://my-overleaf-instance.com
+OVERLEAF_NAV_TITLE=Our Overleaf Instance
+# OVERLEAF_HEADER_IMAGE_URL=http://somewhere.com/mylogo.png
+OVERLEAF_ADMIN_EMAIL=support@example.com
+
+OVERLEAF_LEFT_FOOTER=[{"text": "Contact your support team", "url": "mailto:support@example.com"}]
+OVERLEAF_RIGHT_FOOTER=[{"text":"Hello, I am on the Right", "url":"https://github.com/yu-i-i/overleaf-cep"}]
+
+OVERLEAF_EMAIL_FROM_ADDRESS=team@example.com
+OVERLEAF_EMAIL_SMTP_HOST=smtp.example.com
+OVERLEAF_EMAIL_SMTP_PORT=587
+OVERLEAF_EMAIL_SMTP_SECURE=false
+# OVERLEAF_EMAIL_SMTP_USER=
+# OVERLEAF_EMAIL_SMTP_PASS=
+# OVERLEAF_EMAIL_SMTP_NAME=
+OVERLEAF_EMAIL_SMTP_LOGGER=false
+OVERLEAF_EMAIL_SMTP_TLS_REJECT_UNAUTH=true
+OVERLEAF_EMAIL_SMTP_IGNORE_TLS=false
+OVERLEAF_CUSTOM_EMAIL_FOOTER=This system is run by department x
+
+OVERLEAF_PROXY_LEARN=true
+NAV_HIDE_POWERED_BY=true
+
+########################
+## Sandboxed Compiles ##
+########################
+
+ALL_TEX_LIVE_DOCKER_IMAGES=texlive/texlive:latest-full, texlive/texlive:TL2023-historic
+ALL_TEX_LIVE_DOCKER_IMAGE_NAMES=TeXLive 2024, TeXLive 2023
+TEX_LIVE_DOCKER_IMAGE=texlive/texlive:latest-full
+TEX_COMPILER_EXTRA_FLAGS=-shell-escape
+```
+</details>
+
+## Authentication Methods
+
+The following authentication methods are supported: local authentication, LDAP authentication, SAML authentication,
+and OpenID Connect (OIDC) authentication. Local authentication is always active. The environment variable `EXTERNAL_AUTH`
+specifies which external authentication methods are activated. The value of this variable is a list. If the list includes `ldap`, `saml`, or `oidc`,
+then LDAP authentication, SAML authentication, and OIDC authentication will be activated, respectively. 
+
+For example: `EXTERNAL_AUTH=ldap saml oidc`
+
+This configuration activates all available authentication methods, although this is rarely necessary.
+
+<details>
+<summary><h3>Local Authentication</h3></summary>
+
+Password of local users stored in the MongoDB database. An admin user can create a new local user. For details, visit the
+[wiki of Overleaf project](https://github.com/overleaf/overleaf/wiki/Creating-and-managing-users).
+
+It is possible to enforce password restrictions on local users:
+
+
+* `OVERLEAF_PASSWORD_VALIDATION_MIN_LENGTH`: The minimum length required
+
+* `OVERLEAF_PASSWORD_VALIDATION_MAX_LENGTH`: The maximum length allowed
+
+* `OVERLEAF_PASSWORD_VALIDATION_PATTERN`: is used to validate password strength
+
+  - `abc123` – password requires 3 letters and 3 numbers and be at least 6 characters long
+  - `aA` – password requires lower and uppercase letters and be at least 2 characters long
+  - `ab$3` – it must contain letters, digits and symbols and be at least 4 characters long
+  - There are 4 groups of characters: letters, UPPERcase letters, digits, symbols. Anything that is neither a letter nor a digit is considered to be a symbol.
+
+</details>
+
+<details>
+<summary><h3>LDAP Authentication</h3></summary>
+
+Internally, Overleaf LDAP uses the [passport-ldapauth](https://github.com/vesse/passport-ldapauth) library. Most of these configuration options are passed through to the `server` config object which is used to configure `passport-ldapauth`. If you are having issues configuring LDAP, it is worth reading the README for `passport-ldapauth` to understand the configuration it expects.
+
+When using Local and LDAP authentication methods, a user enters a `username` and `password` in the login form. If LDAP authentication is enabled, it is attempted first:
+
+1. An LDAP user is searched for in the LDAP directory using the filter defined by `OVERLEAF_LDAP_SEARCH_FILTER` and authenticated.
+2. If authentication is successful, the Overleaf users database is checked for a user with the primary email address that matches the email address of the authenticated LDAP user:
+   - If a matching user is found, the `hashedPassword` field for this user is deleted (if it exists). This ensures that the user can only log in via LDAP authentication in the future.
+   - If no matching user is found, a new Overleaf user is created using the email, first name, and last name retrieved from the LDAP server.
+3. If LDAP authentication fails or is unsuccessful, local authentication is attempted.
+
+#### Environment Variables
+
+- `OVERLEAF_LDAP_URL` **(required)**
+    * URL of the LDAP server.
+
+      - Example: `ldaps://ldap.example.com:636` (LDAP over SSL)
+      - Example: `ldap://ldap.example.com:389` (unencrypted or STARTTLS, if configured).
+
+- `OVERLEAF_LDAP_EMAIL_ATT`
+    * The email attribute returned by the LDAP server, default `mail`. Each LDAP user must have at least one email address.
+      If multiple addresses are provided, only the first one will be used.
+
+- `OVERLEAF_LDAP_FIRST_NAME_ATT`
+    * The property name holding the first name of the user which is used in the application, usually `givenName`.
+
+- `OVERLEAF_LDAP_LAST_NAME_ATT`
+    * The property name holding the family name of the user which is used in the application, usually `sn`.
+
+- `OVERLEAF_LDAP_NAME_ATT`
+    * The property name holding the full name of the user, usually `cn`. If either of the two previous variables is not defined,
+      the first and/or last name of the user is extracted from this variable. Otherwise, it is not used.
+
+- `OVERLEAF_LDAP_PLACEHOLDER`
+    * The placeholder for the login form, defaults to `Username`.
+
+- `OVERLEAF_LDAP_UPDATE_USER_DETAILS_ON_LOGIN`
+    * If set to `true`, updates the LDAP user `first_name` and `last_name` field on login, and turn off the user details form on the `/user/settings`
+      page for LDAP users. Otherwise, details will be fetched only on first login.
+
+- `OVERLEAF_LDAP_BIND_DN`
+    * The distinguished name of the LDAP user that should be used for the LDAP connection
+      (this user should be able to search/list accounts on the LDAP server),
+      e.g., `cn=ldap_reader,dc=example,dc=com`. If not defined, anonymous binding is used.
+
+- `OVERLEAF_LDAP_BIND_CREDENTIALS`
+    * Password for `OVERLEAF_LDAP_BIND_DN`.
+
+- `OVERLEAF_LDAP_BIND_PROPERTY`
+    * Property of the user to bind against the client, defaults to `dn`.
+
+- `OVERLEAF_LDAP_SEARCH_BASE` **(required)**
+    * The base DN from which to search for users. E.g., `ou=people,dc=example,dc=com`.
+
+- `OVERLEAF_LDAP_SEARCH_FILTER`
+    * LDAP search filter with which to find a user. Use the literal '{{username}}' to have the given username be interpolated in for the LDAP search.
+
+      - Example: `(|(uid={{username}})(mail={{username}}))` (user can login with email or with login name).
+      - Example: `(sAMAccountName={{username}})` (Active Directory).
+
+- `OVERLEAF_LDAP_SEARCH_SCOPE`
+    * The scope of the search can be `base`, `one`, or `sub` (default).
+
+- `OVERLEAF_LDAP_SEARCH_ATTRIBUTES`
+    * JSON array of attributes to fetch from the LDAP server, e.g., `["uid", "mail", "givenName", "sn"]`.
+      By default, all attributes are fetched.
+
+- `OVERLEAF_LDAP_STARTTLS`
+    * If `true`, LDAP over TLS is used.
+
+- `OVERLEAF_LDAP_TLS_OPTS_CA_PATH`
+    * Path to the file containing the CA certificate used to verify the LDAP server's SSL/TLS certificate. If there are multiple certificates, then
+      it can be a JSON array of paths to the certificates. The files must be accessible to the docker container.
+
+      - Example (one certificate): `/overleaf/certs/ldap_ca_cert.pem`
+      - Example (multiple certificates): `["/overleaf/certs/ldap_ca_cert1.pem", "/overleaf/certs/ldap_ca_cert2.pem"]`
+
+- `OVERLEAF_LDAP_TLS_OPTS_REJECT_UNAUTH`
+    * If `true`, the server certificate is verified against the list of supplied CAs.
+
+- `OVERLEAF_LDAP_CACHE`
+    * If `true`, then up to 100 credentials at a time will be cached for 5 minutes.
+
+- `OVERLEAF_LDAP_TIMEOUT`
+    * How long the client should let operations live for before timing out, ms (Default: Infinity).
+
+- `OVERLEAF_LDAP_CONNECT_TIMEOUT`
+    * How long the client should wait before timing out on TCP connections, ms (Default: OS default).
+
+- `OVERLEAF_LDAP_IS_ADMIN_ATT` and `OVERLEAF_LDAP_IS_ADMIN_ATT_VALUE`
+    * When both environment variables are set, the login process updates `user.isAdmin = true` if the LDAP profile contains the attribute specified by
+     `OVERLEAF_LDAP_IS_ADMIN_ATT` and its value either matches `OVERLEAF_LDAP_IS_ADMIN_ATT_VALUE` or is an array containing `OVERLEAF_LDAP_IS_ADMIN_ATT_VALUE`,
+      otherwise `user.isAdmin` is set to `false`. If either of these variables is not set, then the admin status is only set to `true` during admin user
+      creation in Launchpad.
+
+The following five variables are used to configure how user contacts are retrieved from the LDAP server.
+
+- `OVERLEAF_LDAP_CONTACTS_FILTER`
+    * The filter used to search for users in the LDAP server to be loaded into contacts. The placeholder '{{userProperty}}' within the filter is replaced with the value of
+    the property specified by `OVERLEAF_LDAP_CONTACTS_PROPERTY` from the LDAP user initiating the search. If not defined, no users are retrieved from the LDAP server into contacts.
+
+- `OVERLEAF_LDAP_CONTACTS_SEARCH_BASE`
+    * Specifies the base DN from which to start searching for the contacts. Defaults to `OVERLEAF_LDAP_SEARCH_BASE`.
+
+- `OVERLEAF_LDAP_CONTACTS_SEARCH_SCOPE`
+    * The scope of the search can be `base`, `one`, or `sub` (default).
+
+- `OVERLEAF_LDAP_CONTACTS_PROPERTY`
+    * Specifies the property of the user object that will replace the '{{userProperty}}' placeholder in the `OVERLEAF_LDAP_CONTACTS_FILTER`.
+
+- `OVERLEAF_LDAP_CONTACTS_NON_LDAP_VALUE`
+    * Specifies the value of the `OVERLEAF_LDAP_CONTACTS_PROPERTY` if the search is initiated by a non-LDAP user. If this variable is not defined, the resulting filter
+      will match nothing. The value `*` can be used as a wildcard.
+
+<details>
+<summary><h5>Example</h5></summary>
+
+    OVERLEAF_LDAP_CONTACTS_FILTER=(gidNumber={{userProperty}})
+    OVERLEAF_LDAP_CONTACTS_PROPERTY=gidNumber
+    OVERLEAF_LDAP_CONTACTS_NON_LDAP_VALUE=1000
+
+The above example results in loading into the contacts of the current LDAP user all LDAP users who have the same UNIX `gid`. Non-LDAP users will have all LDAP users with UNIX `gid=1000` in their contacts.
+
+</details>
+
+
+<details>
+<summary><h4>Sample variables.env file</h4></summary>
+
+```
+OVERLEAF_APP_NAME="Our Overleaf Instance"
+
+ENABLED_LINKED_FILE_TYPES=project_file,project_output_file
+
+# Enables Thumbnail generation using ImageMagick
+ENABLE_CONVERSIONS=true
+
+# Disables email confirmation requirement
+EMAIL_CONFIRMATION_DISABLED=true
+
+## Nginx
+# NGINX_WORKER_PROCESSES=4
+# NGINX_WORKER_CONNECTIONS=768
+
+## Set for TLS via nginx-proxy
+# OVERLEAF_BEHIND_PROXY=true
+# OVERLEAF_SECURE_COOKIE=true
+
+OVERLEAF_SITE_URL=http://my-overleaf-instance.com
+OVERLEAF_NAV_TITLE=Our Overleaf Instance
+# OVERLEAF_HEADER_IMAGE_URL=http://somewhere.com/mylogo.png
+OVERLEAF_ADMIN_EMAIL=support@example.com
+
+OVERLEAF_LEFT_FOOTER=[{"text": "Contact your support team", "url": "mailto:support@example.com"}]
+OVERLEAF_RIGHT_FOOTER=[{"text":"Hello, I am on the Right", "url":"https://github.com/yu-i-i/overleaf-cep"}]
+
+OVERLEAF_EMAIL_FROM_ADDRESS=team@example.com
+OVERLEAF_EMAIL_SMTP_HOST=smtp.example.com
+OVERLEAF_EMAIL_SMTP_PORT=587
+OVERLEAF_EMAIL_SMTP_SECURE=false
+# OVERLEAF_EMAIL_SMTP_USER=
+# OVERLEAF_EMAIL_SMTP_PASS=
+# OVERLEAF_EMAIL_SMTP_NAME=
+OVERLEAF_EMAIL_SMTP_LOGGER=false
+OVERLEAF_EMAIL_SMTP_TLS_REJECT_UNAUTH=true
+OVERLEAF_EMAIL_SMTP_IGNORE_TLS=false
+OVERLEAF_CUSTOM_EMAIL_FOOTER=This system is run by department x
+
+OVERLEAF_PROXY_LEARN=true
+NAV_HIDE_POWERED_BY=true
+
+#################
+## LDAP for CE ##
+#################
+
+EXTERNAL_AUTH=ldap
+OVERLEAF_LDAP_URL=ldap://ldap.example.com:389
+OVERLEAF_LDAP_STARTTLS=true
+OVERLEAF_LDAP_TLS_OPTS_CA_PATH=/overleaf/certs/ldap_ca_cert.pem
+OVERLEAF_LDAP_SEARCH_BASE=ou=people,dc=example,dc=com
+OVERLEAF_LDAP_SEARCH_FILTER=(|(uid={{username}})(mail={{username}}))
+OVERLEAF_LDAP_BIND_DN=cn=ldap_reader,dc=example,dc=com
+OVERLEAF_LDAP_BIND_CREDENTIALS=GoodNewsEveryone
+OVERLEAF_LDAP_EMAIL_ATT=mail
+OVERLEAF_LDAP_FIRST_NAME_ATT=givenName
+OVERLEAF_LDAP_LAST_NAME_ATT=sn
+# OVERLEAF_LDAP_NAME_ATT=cn
+OVERLEAF_LDAP_SEARCH_ATTRIBUTES=["uid", "sn", "givenName", "mail"]
+
+OVERLEAF_LDAP_UPDATE_USER_DETAILS_ON_LOGIN=true
+
+OVERLEAF_LDAP_PLACEHOLDER='Username or email address'
+
+OVERLEAF_LDAP_IS_ADMIN_ATT=mail
+OVERLEAF_LDAP_IS_ADMIN_ATT_VALUE=admin@example.com
+
+OVERLEAF_LDAP_CONTACTS_FILTER=(gidNumber={{userProperty}})
+OVERLEAF_LDAP_CONTACTS_PROPERTY=gidNumber
+OVERLEAF_LDAP_CONTACTS_NON_LDAP_VALUE='*'
+```
+</details>
+
+<details>
+<summary><i>Deprecated variables</i></summary>
+
+**These variables will be removed soon**, use `OVERLEAF_LDAP_IS_ADMIN_ATT` and `OVERLEAF_LDAP_IS_ADMIN_ATT_VALUE` instead.
+
+The following variables are used to determine if the user has admin rights.
+Please note: the user gains admin status if the search result is not empty, not when the user is explicitly included in the search results.
+
+- `OVERLEAF_LDAP_ADMIN_SEARCH_BASE`
+    * Specifies the base DN from which to start searching for the admin group. If this variable is defined,
+    `OVERLEAF_LDAP_ADMIN_SEARCH_FILTER` must also be defined for the search to function properly.
+
+- `OVERLEAF_LDAP_ADMIN_SEARCH_FILTER`
+    * Defines the LDAP search filter used to identify the admin group. The placeholder `{{dn}}` within the filter
+      is replaced with the value of the property specified by `OVERLEAF_LDAP_ADMIN_DN_PROPERTY`. The placeholder `{{username}}` is also supported.
+
+- `OVERLEAF_LDAP_ADMIN_DN_PROPERTY`
+    * Specifies the property of the user object that will replace the '{{dn}}' placeholder
+      in the `OVERLEAF_LDAP_ADMIN_SEARCH_FILTER`, defaults to `dn`.
+
+- `OVERLEAF_LDAP_ADMIN_SEARCH_SCOPE`
+    * The scope of the LDAP search can be `base`, `one`, or `sub` (default)
+
+<details>
+<summary><h5>Example</h5></summary>
+
+In the following example admins are members of a group `admins`, the objectClass of the entry `admins` is `groupOfNames`:
+
+    OVERLEAF_LDAP_ADMIN_SEARCH_BASE='cn=admins,ou=group,dc=example,dc=com'
+    OVERLEAF_LDAP_ADMIN_SEARCH_FILTER='(member={{dn}})'
+
+In the following example admins are members of a group 'admins', the objectClass of the entry `admins` is `posixGroup`:
+
+    OVERLEAF_LDAP_ADMIN_SEARCH_BASE='cn=admins,ou=group,dc=example,dc=com'
+    OVERLEAF_LDAP_ADMIN_SEARCH_FILTER='(memberUid={{username}})'
+
+In the following example admins are users with UNIX gid=1234:
+
+    OVERLEAF_LDAP_ADMIN_SEARCH_BASE='ou=people,dc=example,dc=com'
+    OVERLEAF_LDAP_ADMIN_SEARCH_FILTER='(&(gidNumber=1234)(uid={{username}}))'
+
+In the following example admin is the user with `uid=someuser`:
+
+    OVERLEAF_LDAP_ADMIN_SEARCH_BASE='ou=people,dc=example,dc=com'
+    OVERLEAF_LDAP_ADMIN_SEARCH_FILTER='(&(uid=someuser)(uid={{username}}))'
+
+The filter
+
+    OVERLEAF_LDAP_ADMIN_SEARCH_FILTER='(uid=someuser)'
+
+where `someuser` is the uid of an existing user, will always produce a non-empty search result.
+As a result, **every user will be granted admin rights**, not just `someuser`, as one might expect.
+
+</details>
+</details>
+</details>
+
+<details>
+<summary><h3>SAML Authentication</h3></summary>
+
+Internally, Overleaf SAML module uses the [passport-saml](https://github.com/node-saml/passport-saml) library, most of the following
+configuration options are passed through to `passport-saml`. If you are having issues configuring SAML, it is worth reading the README
+for `passport-saml` to get a feel for the configuration it expects.
+
+When using the SAML authentication method, a user is redirected to the Identity Provider (IdP) authentication site.
+If the IdP successfully authenticates the user, the Overleaf users database is checked for a record containing a `samlIdentifiers` field structured as follows:
+
+```
+samlIdentifiers: [
+  {
+    externalUserId: "...",
+    providerId: "1",
+    userIdAttribute: "..."
+  }
+]
+```
+The `externalUserId` must match the value of the property specified by `userIdAttribute` in the user profile returned by the IdP server.
+
+If no matching record is found, the database is searched for a user with the primary email address matching the email in the IdP user profile:
+
+- If such a user is found, the `hashedPassword` field is deleted to disable local authentication, and the `samlIdentifiers` field is added.
+- If no matching user is found, a new user is created with the email address and `samlIdentifiers` from the IdP profile.
+
+**Note:** Currently, only one SAML IdP is supported. The `providerId` field in `samlIdentifiers` is fixed to `'1'`.
+
+#### Environment Variables
+
+- `OVERLEAF_SAML_IDENTITY_SERVICE_NAME`
+    * Display name for the identity service, used on the login page (default: `Log in with SAML IdP`).
+
+- `OVERLEAF_SAML_USER_ID_FIELD`
+    * The value of this attribute will be used by Overleaf as the external user ID, defaults to `nameID`.
+
+- `OVERLEAF_SAML_EMAIL_FIELD`
+    * Name of the Email field in user profile, defaults to `nameID`.
+
+- `OVERLEAF_SAML_FIRST_NAME_FIELD`
+    * Name of the firstName field in user profile, defaults to `givenName`.
+
+- `OVERLEAF_SAML_LAST_NAME_FIELD`
+    * Name of the lastName field in user profile, defaults to `lastName`
+
+- `OVERLEAF_SAML_UPDATE_USER_DETAILS_ON_LOGIN`
+    * If set to `true`, updates the user `first_name` and `last_name` field on login,
+      and turn off the user details form on `/user/settings` page.
+
+- `OVERLEAF_SAML_ENTRYPOINT` **(required)**
+    * Entrypoint URL for the SAML identity service.
+
+      - Example: `https://idp.example.com/simplesaml/saml2/idp/SSOService.php`
+      - Azure Example: `https://login.microsoftonline.com/8b26b46a-6dd3-45c7-a104-f883f4db1f6b/saml2`
+
+- `OVERLEAF_SAML_ISSUER` **(required)**
+    * The Issuer name.
+
+- `OVERLEAF_SAML_AUDIENCE`
+    * Expected saml response Audience, defaults to value of `OVERLEAF_SAML_ISSUER`.
+
+- `OVERLEAF_SAML_IDP_CERT` **(required)**
+    * Path to a file containing the Identity Provider's public certificate, used to validate the signatures of incoming SAML responses. If the Identity Provider has multiple valid signing certificates, then
+      it can be a JSON array of paths to the certificates.
+
+        - Example (one certificate): `/overleaf/certs/idp_cert.pem`
+        - Example (multiple certificates): `["/overleaf/certs/idp_cert.pem", "/overleaf/certs/idp_cert_old.pem"]`
+
+- `OVERLEAF_SAML_PUBLIC_CERT`
+    * Path to a file containing public signing certificate used to embed in auth requests in order for the IdP to validate the signatures of the incoming SAML Request. It's required when setting up the [metadata endpoint](#metadata-for-the-identity-provider)
+      when the strategy is configured with a `OVERLEAF_SAML_PRIVATE_KEY`. A JSON array of paths to certificates can be provided to support certificate rotation. When supplying an array of certificates, the first entry in the array should match the
+      current `OVERLEAF_SAML_PRIVATE_KEY`. Additional entries in the array can be used to publish upcoming certificates to IdPs before changing the `OVERLEAF_SAML_PRIVATE_KEY`.
+
+- `OVERLEAF_SAML_PRIVATE_KEY`
+    * Path to a file containing a PEM-formatted private key matching the `OVERLEAF_SAML_PUBLIC_CERT` used to sign auth requests sent by passport-saml.
+
+- `OVERLEAF_SAML_DECRYPTION_CERT`
+    *  Path to a file containing public certificate, used for the [metadata endpoint](#metadata-for-the-identity-provider).
+
+- `OVERLEAF_SAML_DECRYPTION_PVK`
+    * Path to a file containing private key  matching the `OVERLEAF_SAML_DECRYPTION_CERT` that will be used to attempt to decrypt any encrypted assertions that are received.
+
+- `OVERLEAF_SAML_SIGNATURE_ALGORITHM`
+    * Optionally set the signature algorithm for signing requests,
+          valid values are 'sha1' (default), 'sha256' (prefered), 'sha512' (most secure, check if your IdP supports it).
+
+- `OVERLEAF_SAML_ADDITIONAL_PARAMS`
+    * JSON dictionary of additional query params to add to all requests.
+
+- `OVERLEAF_SAML_ADDITIONAL_AUTHORIZE_PARAMS`
+    * JSON dictionary of additional query params to add to 'authorize' requests.
+
+        - Example: `{"some_key": "some_value"}`
+
+- `OVERLEAF_SAML_IDENTIFIER_FORMAT`
+    * Name identifier format to request from the identity provider (default: `urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress`).
+      If using `urn:oasis:names:tc:SAML:2.0:nameid-format:persistent`, ensure the `OVERLEAF_SAML_EMAIL_FIELD` envirionment variable is defined.
+      If `urn:oasis:names:tc:SAML:2.0:nameid-format:transient` is required, you must also define the `OVERLEAF_SAML_ID_FIELD` environment variable,
+      which can, for example, be set to the user's email address.
+
+- `OVERLEAF_SAML_ACCEPTED_CLOCK_SKEW_MS`
+    * Time in milliseconds of skew that is acceptable between client and server when checking OnBefore and NotOnOrAfter assertion
+          condition validity timestamps. Setting to -1 will disable checking these conditions entirely. Default is 0.
+
+- `OVERLEAF_SAML_ATTRIBUTE_CONSUMING_SERVICE_INDEX`
+    * `AttributeConsumingServiceIndex` attribute to add to AuthnRequest to instruct the IdP which attribute set to attach
+          to the response ([link](http://blog.aniljohn.com/2014/01/data-minimization-front-channel-saml-attribute-requests.html)).
+
+- `OVERLEAF_SAML_AUTHN_CONTEXT`
+    * JSON array of name identifier format values to request auth context. Default: `["urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport"]`.
+
+- `OVERLEAF_SAML_FORCE_AUTHN`
+    * If `true`, the initial SAML request from the service provider specifies that the IdP should force re-authentication of the user,
+          even if they possess a valid session.
+
+- `OVERLEAF_SAML_DISABLE_REQUESTED_AUTHN_CONTEXT`
+    * If `true`, do not request a specific auth context. For example, you can this this to `true` to allow additional contexts such as password-less logins (`urn:oasis:names:tc:SAML:2.0:ac:classes:X509`). Support for additional contexts is dependant on your IdP.
+
+- `OVERLEAF_SAML_AUTHN_REQUEST_BINDING`
+    * If set to `HTTP-POST`, will request authentication from IdP via HTTP POST binding, otherwise defaults to HTTP-Redirect.
+
+- `OVERLEAF_SAML_VALIDATE_IN_RESPONSE_TO`
+    * If `always`, then InResponseTo will be validated from incoming SAML responses.
+    * If `never`, then InResponseTo  won't be validated (default).
+    * If `ifPresent`, then InResponseTo will only be validated if present in the incoming SAML response.
+
+- `OVERLEAF_SAML_REQUEST_ID_EXPIRATION_PERIOD_MS`
+    * Defines the expiration time when a Request ID generated for a SAML request will not be valid if seen
+          in a SAML response in the `InResponseTo` field. Default: 28800000 (8 hours).
+
+- `OVERLEAF_SAML_LOGOUT_URL`
+    * base address to call with logout requests (default: `entryPoint`).
+
+      - Example: `https://idp.example.com/simplesaml/saml2/idp/SingleLogoutService.php`
+
+- `OVERLEAF_SAML_ADDITIONAL_LOGOUT_PARAMS`
+    * JSON dictionary of additional query params to add to 'logout' requests.
+
+- `OVERLEAF_SAML_IS_ADMIN_FIELD` and `OVERLEAF_SAML_IS_ADMIN_FIELD_VALUE`
+    * When both environment variables are set, the login process updates `user.isAdmin = true` if the profile returned by the SAML IdP contains the attribute specified by
+     `OVERLEAF_SAML_IS_ADMIN_FIELD` and its value either matches `OVERLEAF_SAML_IS_ADMIN_FIELD_VALUE` or is an array containing `OVERLEAF_SAML_IS_ADMIN_FIELD_VALUE`,
+      otherwise `user.isAdmin` is set to `false`. If either of these variables is not set, then the admin status is only set to `true` during admin user
+      creation in Launchpad.
+
+#### Metadata for the Identity Provider
+
+The current version of Overleaf CE includes and endpoint to retrieve Service Provider Metadata: `http://my-overleaf-instance.com/saml/meta`
+
+The Identity Provider will need to be configured to recognize the Overleaf server as a "Service Provider". Consult the documentation for your SAML server for instructions on how to do this.
+
+Below is an example of appropriate Service Provider metadata:
+
+<details>
+<summary><h5>ol-meta.xml</h5></summary>
+
+```
+<?xml version="1.0"?>
+<EntityDescriptor xmlns="urn:oasis:names:tc:SAML:2.0:metadata"
+                  xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
+                  entityID="MyOverleaf"
+                  ID="_b508c83b7dda452f5b269383fb391107116f8f57">
+  <SPSSODescriptor protocolSupportEnumeration="urn:oasis:names:tc:SAML:2.0:protocol" AuthnRequestsSigned="true" WantAssertionsSigned="true">
+    <KeyDescriptor use="signing">
+      <ds:KeyInfo>
+        <ds:X509Data>
+          <ds:X509Certificate>MII...
+[skipped]
+</ds:X509Certificate>
+        </ds:X509Data>
+      </ds:KeyInfo>
+    </KeyDescriptor>
+    <KeyDescriptor use="encryption">
+      <ds:KeyInfo>
+        <ds:X509Data>
+          <ds:X509Certificate>MII...
+[skipped]
+</ds:X509Certificate>
+        </ds:X509Data>
+      </ds:KeyInfo>
+      <EncryptionMethod Algorithm="http://www.w3.org/2009/xmlenc11#aes256-gcm"/>
+      <EncryptionMethod Algorithm="http://www.w3.org/2009/xmlenc11#aes128-gcm"/>
+      <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#aes256-cbc"/>
+      <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#aes128-cbc"/>
+    </KeyDescriptor>
+    <SingleLogoutService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST"
+                         Location="https://my-overleaf-instance.com/saml/logout/callback"/>
+    <NameIDFormat>urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress</NameIDFormat>
+    <AssertionConsumerService index="1"
+                              isDefault="true"
+                              Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST"
+                              Location="https://my-overleaf-instance.com/saml/login/callback"/>
+  </SPSSODescriptor>
+</EntityDescriptor>
+
+```
+</details>
+
+Note the certificates, `AssertionConsumerService.Location`, `SingleLogoutService.Location` and `EntityDescriptor.entityID`
+and set as appropriate in your IdP configuration, or send the metadata file to the IdP admin.
+
+<details>
+<summary><h4>Sample variables.env file</h4></summary>
+
+```
+OVERLEAF_APP_NAME="Our Overleaf Instance"
+
+ENABLED_LINKED_FILE_TYPES=project_file,project_output_file
+
+# Enables Thumbnail generation using ImageMagick
+ENABLE_CONVERSIONS=true
+
+# Disables email confirmation requirement
+EMAIL_CONFIRMATION_DISABLED=true
+
+## Nginx
+# NGINX_WORKER_PROCESSES=4
+# NGINX_WORKER_CONNECTIONS=768
+
+## Set for TLS via nginx-proxy
+# OVERLEAF_BEHIND_PROXY=true
+# OVERLEAF_SECURE_COOKIE=true
+
+OVERLEAF_SITE_URL=http://my-overleaf-instance.com
+OVERLEAF_NAV_TITLE=Our Overleaf Instance
+# OVERLEAF_HEADER_IMAGE_URL=http://somewhere.com/mylogo.png
+OVERLEAF_ADMIN_EMAIL=support@example.com
+
+OVERLEAF_LEFT_FOOTER=[{"text": "Contact your support team", "url": "mailto:support@example.com"}]
+OVERLEAF_RIGHT_FOOTER=[{"text":"Hello, I am on the Right", "url":"https://github.com/yu-i-i/overleaf-cep"}]
+
+OVERLEAF_EMAIL_FROM_ADDRESS=team@example.com
+OVERLEAF_EMAIL_SMTP_HOST=smtp.example.com
+OVERLEAF_EMAIL_SMTP_PORT=587
+OVERLEAF_EMAIL_SMTP_SECURE=false
+# OVERLEAF_EMAIL_SMTP_USER=
+# OVERLEAF_EMAIL_SMTP_PASS=
+# OVERLEAF_EMAIL_SMTP_NAME=
+OVERLEAF_EMAIL_SMTP_LOGGER=false
+OVERLEAF_EMAIL_SMTP_TLS_REJECT_UNAUTH=true
+OVERLEAF_EMAIL_SMTP_IGNORE_TLS=false
+OVERLEAF_CUSTOM_EMAIL_FOOTER=This system is run by department x
+
+OVERLEAF_PROXY_LEARN=true
+NAV_HIDE_POWERED_BY=true
+
+#################
+## SAML for CE ##
+#################
+
+EXTERNAL_AUTH=saml
+OVERLEAF_SAML_IDENTITY_SERVICE_NAME='Log in with My IdP'
+OVERLEAF_SAML_EMAIL_FIELD=mail
+OVERLEAF_SAML_FIRST_NAME_FIELD=givenName
+OVERLEAF_SAML_LAST_NAME_FIELD=sn
+OVERLEAF_SAML_ENTRYPOINT=https://idp.example.com/simplesamlphp/saml2/idp/SSOService.php
+OVERLEAF_SAML_CALLBACK_URL=https://my-overleaf-instance.com/saml/login/callback
+OVERLEAF_SAML_LOGOUT_URL=https://idp.example.com/simplesamlphp/saml2/idp/SingleLogoutService.php
+OVERLEAF_SAML_LOGOUT_CALLBACK_URL=https://my-overleaf-instance.com/saml/logout/callback
+OVERLEAF_SAML_ISSUER=MyOverleaf
+OVERLEAF_SAML_IDP_CERT=/overleaf/certs/idp_cert.pem
+OVERLEAF_SAML_PUBLIC_CERT=/overleaf/certs/myol_cert.pem
+OVERLEAF_SAML_PRIVATE_KEY=/overleaf/certs/myol_key.pem
+OVERLEAF_SAML_DECRYPTION_CERT=/overleaf/certs/myol_decr_cert.pem
+OVERLEAF_SAML_DECRYPTION_PVK=/overleaf/certs/myol_decr_key.pem
+OVERLEAF_SAML_IS_ADMIN_FIELD=mail
+OVERLEAF_SAML_IS_ADMIN_FIELD_VALUE=overleaf.admin@example.com
+```
+</details>
+</details>
+
+<details>
+<summary><h3>OIDC Authentication</h3></summary>
+
+Internally, Overleaf OIDC module uses the [passport-openidconnect](https://github.com/jaredhanson/passport-openidconnect) library.
+If you are having issues configuring OpenID Connect, it is worth reading the README for `passport-openidconnect` to get a feel for the configuration it expects.
+
+
+When using the OIDC authentication method, a user is redirected to the Identity Provider (IdP) authentication site.
+If the IdP successfully authenticates the user, the Overleaf users database is checked for a record containing a `thirdPartyIdentifiers` field structured as follows:
+
+```
+thirdPartyIdentifiers: [
+  {
+    externalUserId: "...",
+    externalData: null,
+    providerId: "..."
+  }
+]
+```
+
+The `externalUserId` must match the user ID in the profile returned by the IdP server (see the `OVERLEAF_OIDC_USER_ID_FIELD` environment variable), and `providerId`
+must match the ID of the OIDC provider (see the `OVERLEAF_OIDC_PROVIDER_ID`).
+
+If no matching record is found, the database is searched for a user with the primary email address matching the email in the IdP user profile:
+- If such a user is found, the `thirdPartyIdentifiers` field is updated.
+- If no matching user is found, a new user is created with the email address and `thirdPartyIdentifiers` from the IdP profile.
+
+In both cases, the user is said to be 'linked' to the external OIDC user. The user can be unlinked from the OIDC provider on the `/user/settings` page.
+
+
+#### Environment Variables
+
+The values of the following five required variables can be found using `.well-known/openid-configuration` endpoint of your OpenID Provider (OP).
+
+- `OVERLEAF_OIDC_ISSUER` **(required)**
+
+- `OVERLEAF_OIDC_AUTHORIZATION_URL` **(required)**
+
+- `OVERLEAF_OIDC_TOKEN_URL` **(required)**
+
+- `OVERLEAF_OIDC_USER_INFO_URL` **(required)**
+
+- `OVERLEAF_OIDC_LOGOUT_URL` **(required)**
+
+The values of the following two required variables will be provided by the admin of your OP
+
+- `OVERLEAF_OIDC_CLIENT_ID` **(required)**
+
+- `OVERLEAF_OIDC_CLIENT_SECRET` **(required)**
+
+- `OVERLEAF_OIDC_SCOPE`
+    * Default: `openid profile email`
+
+- `OVERLEAF_OIDC_PROVIDER_ID`
+    * Arbitrary ID of the OP, defaults to `oidc`.
+
+- `OVERLEAF_OIDC_PROVIDER_NAME`
+    * The name of the OP, used in the `Linked Accounts` section of the `/user/settings` page, defaults to `OIDC Provider`.
+
+- `OVERLEAF_OIDC_IDENTITY_SERVICE_NAME`
+    * Display name for the identity service, used on the login page (default: `Log in with $OVERLEAF_OIDC_PROVIDER_NAME`).
+
+- `OVERLEAF_OIDC_PROVIDER_DESCRIPTION`
+    * Description of OP, used in the `Linked Accounts` section (default: `Log in with $OVERLEAF_OIDC_PROVIDER_NAME`).
+
+- `OVERLEAF_OIDC_PROVIDER_INFO_LINK`
+    * `Learn more` URL in the OP description, default: no `Learn more` link in the description.
+
+- `OVERLEAF_OIDC_PROVIDER_HIDE_NOT_LINKED`
+    * Do not show OP on the `/user/settings` page, if the user's account is not linked with the OP, default `false`.
+
+- `OVERLEAF_OIDC_USER_ID_FIELD`
+    * The value of this attribute will be used by Overleaf as the external user ID, defaults to `id`.
+
+- `OVERLEAF_OIDC_UPDATE_USER_DETAILS_ON_LOGIN`
+    * If set to `true`, updates the user `first_name` and `last_name` field on login,
+      and disables the user details form on `/user/settings` page.
+
+- `OVERLEAF_OIDC_IS_ADMIN_FIELD` and `OVERLEAF_OIDC_IS_ADMIN_FIELD_VALUE`
+    * When both environment variables are set, the login process updates `user.isAdmin = true` if the profile returned by the OP contains the attribute specified by
+      `OVERLEAF_OIDC_IS_ADMIN_FIELD` and its value matches `OVERLEAF_OIDC_IS_ADMIN_FIELD_VALUE`, otherwise `user.isAdmin` is set to `false`.
+      If `OVERLEAF_OIDC_IS_ADMIN_FIELD` is `email` then the value of the attribute `emails[0].value` is used for match checking.
+
+<details>
+<summary><h4>Sample variables.env file</h4></summary>
+
+```
+OVERLEAF_APP_NAME="Our Overleaf Instance"
+
+ENABLED_LINKED_FILE_TYPES=project_file,project_output_file
+
+# Enables Thumbnail generation using ImageMagick
+ENABLE_CONVERSIONS=true
+
+# Disables email confirmation requirement
+EMAIL_CONFIRMATION_DISABLED=true
+
+## Nginx
+# NGINX_WORKER_PROCESSES=4
+# NGINX_WORKER_CONNECTIONS=768
+
+## Set for TLS via nginx-proxy
+# OVERLEAF_BEHIND_PROXY=true
+# OVERLEAF_SECURE_COOKIE=true
+
+OVERLEAF_SITE_URL=http://my-overleaf-instance.com
+OVERLEAF_NAV_TITLE=Our Overleaf Instance
+# OVERLEAF_HEADER_IMAGE_URL=http://somewhere.com/mylogo.png
+OVERLEAF_ADMIN_EMAIL=support@example.com
+
+OVERLEAF_LEFT_FOOTER=[{"text": "Contact your support team", "url": "mailto:support@example.com"}]
+OVERLEAF_RIGHT_FOOTER=[{"text":"Hello, I am on the Right", "url":"https://github.com/yu-i-i/overleaf-cep"}]
+
+OVERLEAF_EMAIL_FROM_ADDRESS=team@example.com
+OVERLEAF_EMAIL_SMTP_HOST=smtp.example.com
+OVERLEAF_EMAIL_SMTP_PORT=587
+OVERLEAF_EMAIL_SMTP_SECURE=false
+# OVERLEAF_EMAIL_SMTP_USER=
+# OVERLEAF_EMAIL_SMTP_PASS=
+# OVERLEAF_EMAIL_SMTP_NAME=
+OVERLEAF_EMAIL_SMTP_LOGGER=false
+OVERLEAF_EMAIL_SMTP_TLS_REJECT_UNAUTH=true
+OVERLEAF_EMAIL_SMTP_IGNORE_TLS=false
+OVERLEAF_CUSTOM_EMAIL_FOOTER=This system is run by department x
+
+OVERLEAF_PROXY_LEARN=true
+NAV_HIDE_POWERED_BY=true
+
+#################
+## OIDC for CE ##
+#################
+
+EXTERNAL_AUTH=oidc
+
+OVERLEAF_OIDC_PROVIDER_ID=oidc
+OVERLEAF_OIDC_ISSUER=https://keycloak.provider.com/realms/example
+OVERLEAF_OIDC_AUTHORIZATION_URL=https://keycloak.provider.com/realms/example/protocol/openid-connect/auth
+OVERLEAF_OIDC_TOKEN_URL=https://keycloak.provider.com/realms/example/protocol/openid-connect/token
+OVERLEAF_OIDC_USER_INFO_URL=https://keycloak.provider.com/realms/example/protocol/openid-connect/userinfo
+OVERLEAF_OIDC_LOGOUT_URL=https://keycloak.provider.com/realms/example/protocol/openid-connect/logout
+OVERLEAF_OIDC_CLIENT_ID=Overleaf-OIDC
+OVERLEAF_OIDC_CLIENT_SECRET=DoNotUseThisATGgaAcTgCcATgGATTACAagGtTCaGcGTAG
+OVERLEAF_OIDC_IDENTITY_SERVICE_NAME='Log in with Keycloak OIDC Provider'
+OVERLEAF_OIDC_PROVIDER_NAME=OIDC Keycloak Provider
+OVERLEAF_OIDC_PROVIDER_INFO_LINK=https://openid.net
+OVERLEAF_OIDC_IS_ADMIN_FIELD=email
+OVERLEAF_OIDC_IS_ADMIN_FIELD_VALUE=overleaf.admin@example.com
+OVERLEAF_OIDC_UPDATE_USER_DETAILS_ON_LOGIN=false
+```
+</details>
+</details>

 ## Overleaf Docker Image

@@ -45,8 +881,8 @@ This repo contains two dockerfiles, [`Dockerfile-base`](server-ce/Dockerfile-bas
 `sharelatex/sharelatex-base` image, and [`Dockerfile`](server-ce/Dockerfile) which builds the
 `sharelatex/sharelatex` (or "community") image.

-The Base image generally contains the basic dependencies like `wget` and
-`aspell`, plus `texlive`. We split this out because it's a pretty heavy set of
+The Base image generally contains the basic dependencies like `wget`, plus `texlive`.
+We split this out because it's a pretty heavy set of
 dependencies, and it's nice to not have to rebuild all of that every time.

 The `sharelatex/sharelatex` image extends the base image and adds the actual Overleaf code
@@ -60,14 +896,11 @@ in which to run the Overleaf services. Baseimage uses the `runit` service
 manager to manage services, and we add our init-scripts from the `server-ce/runit`
 folder.

-
-## Contributing
-
-Please see the [CONTRIBUTING](CONTRIBUTING.md) file for information on contributing to the development of Overleaf.
-
 ## Authors

 [The Overleaf Team](https://www.overleaf.com/about)
+<br>
+Extensions for CE by: [yu-i-i](https://github.com/yu-i-i/overleaf-cep)

 ## License

@@ -13,7 +13,8 @@ NOTIFICATIONS_HOST=notifications
 PROJECT_HISTORY_HOST=project-history
 REALTIME_HOST=real-time
 REDIS_HOST=redis
-SPELLING_HOST=spelling
+REFERENCES_HOST=references
+SESSION_SECRET=foo
 WEBPACK_HOST=webpack
 WEB_API_PASSWORD=overleaf
 WEB_API_USER=overleaf
@@ -112,6 +112,17 @@ services:
      - ../services/real-time/app.js:/overleaf/services/real-time/app.js
      - ../services/real-time/config:/overleaf/services/real-time/config

+  references:
+    command: ["node", "--watch", "app.js"]
+    environment:
+      - NODE_OPTIONS=--inspect=0.0.0.0:9229
+    ports:
+      - "127.0.0.1:9236:9229"
+    volumes:
+      - ../services/references/app:/overleaf/services/references/app
+      - ../services/references/config:/overleaf/services/references/config
+      - ../services/references/app.js:/overleaf/services/references/app.js
+
  web:
    command: ["node", "--watch", "app.js", "--watch-locales"]
    environment:
@@ -8,7 +8,6 @@ volumes:
  mongo-data:
  redis-data:
  sharelatex-data:
-  spelling-cache:
  web-data:
  history-v1-buckets:

@@ -124,14 +123,12 @@ services:
    volumes:
      - redis-data:/data

-  spelling:
+  references:
    build:
      context: ..
-      dockerfile: services/spelling/Dockerfile
+      dockerfile: services/references/Dockerfile
    env_file:
      - dev.env
-    volumes:
-      - spelling-cache:/overleaf/services/spelling/cache

  web:
    build:
@@ -146,7 +143,7 @@ services:
      - EMAIL_CONFIRMATION_DISABLED=true
      - NODE_ENV=development
      - OVERLEAF_ALLOW_PUBLIC_ACCESS=true
-    command: ["node", "app.js"]
+    command: ["node", "app.mjs"]
    volumes:
      - sharelatex-data:/var/lib/overleaf
      - web-data:/overleaf/services/web/data
@@ -163,13 +160,13 @@ services:
      - notifications
      - project-history
      - real-time
-      - spelling
+      - references

  webpack:
    build:
      context: ..
      dockerfile: services/web/Dockerfile
-      target: dev
+      target: webpack
    command: ["npx", "webpack", "serve", "--config", "webpack.config.dev-env.js"]
    ports:
      - "127.0.0.1:80:3808"
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ access-token-encryptor
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -1,5 +1,5 @@
-const { promisify } = require('util')
-const crypto = require('crypto')
+const { promisify } = require('node:util')
+const crypto = require('node:crypto')

 const ALGORITHM = 'aes-256-ctr'

@@ -1,4 +1,13 @@
 const chai = require('chai')
 const chaiAsPromised = require('chai-as-promised')
+const SandboxedModule = require('sandboxed-module')

 chai.use(chaiAsPromised)
+
+SandboxedModule.configure({
+  sourceTransformers: {
+    removeNodePrefix: function (source) {
+      return source.replace(/require\(['"]node:/g, "require('")
+    },
+  },
+})
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ fetch-utils
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -1,9 +1,9 @@
 const _ = require('lodash')
-const { Readable } = require('stream')
+const { Readable } = require('node:stream')
 const OError = require('@overleaf/o-error')
 const fetch = require('node-fetch')
-const http = require('http')
-const https = require('https')
+const http = require('node:http')
+const https = require('node:https')

 /**
 * @import { Response } from 'node-fetch'
@@ -1,7 +1,7 @@
 const { expect } = require('chai')
 const { FetchError, AbortError } = require('node-fetch')
-const { Readable } = require('stream')
-const { once } = require('events')
+const { Readable } = require('node:stream')
+const { once } = require('node:events')
 const { TestServer } = require('./helpers/TestServer')
 const selfsigned = require('selfsigned')
 const {
@@ -24,13 +24,17 @@ const pems = selfsigned.generate(attrs, { days: 365 })
 const PRIVATE_KEY = pems.private
 const PUBLIC_CERT = pems.cert

-const dns = require('dns')
+const dns = require('node:dns')
 const _originalLookup = dns.lookup
 // Custom DNS resolver function
 dns.lookup = (hostname, options, callback) => {
  if (hostname === 'example.com') {
    // If the hostname is our test case, return the ip address for the test server
-    callback(null, '127.0.0.1', 4)
+    if (options?.all) {
+      callback(null, [{ address: '127.0.0.1', family: 4 }])
+    } else {
+      callback(null, '127.0.0.1', 4)
+    }
  } else {
    // Otherwise, use the default lookup
    _originalLookup(hostname, options, callback)
@@ -1,9 +1,9 @@
 const express = require('express')
 const bodyParser = require('body-parser')
-const { EventEmitter } = require('events')
-const http = require('http')
-const https = require('https')
-const { promisify } = require('util')
+const { EventEmitter } = require('node:events')
+const http = require('node:http')
+const https = require('node:https')
+const { promisify } = require('node:util')

 class TestServer {
  constructor() {
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ logger
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -1,5 +1,5 @@
 const { fetchString } = require('@overleaf/fetch-utils')
-const fs = require('fs')
+const fs = require('node:fs')

 class LogLevelChecker {
  constructor(logger, defaultLevel) {
@@ -1,7 +1,6 @@
-const Stream = require('stream')
+const Stream = require('node:stream')
 const bunyan = require('bunyan')
 const GCPManager = require('./gcp-manager')
-const SentryManager = require('./sentry-manager')
 const Serializers = require('./serializers')
 const {
  FileLogLevelChecker,
@@ -33,10 +32,6 @@ const LoggingManager = {
    return this
  },

-  initializeErrorReporting(dsn, options) {
-    this.sentryManager = new SentryManager()
-  },
-
  /**
   * @param {Record<string, any>|string} attributes - Attributes to log (nice serialization for err, req, res)
   * @param {string} [message] - Optional message
@@ -68,9 +63,6 @@ const LoggingManager = {
      })
    }
    this.logger.error(attributes, message, ...Array.from(args))
-    if (this.sentryManager) {
-      this.sentryManager.captureExceptionRateLimited(attributes, message)
-    }
  },

  /**
@@ -98,9 +90,6 @@ const LoggingManager = {
   */
  fatal(attributes, message) {
    this.logger.fatal(attributes, message)
-    if (this.sentryManager) {
-      this.sentryManager.captureException(attributes, message, 'fatal')
-    }
  },

  _getOutputStreamConfig() {
@@ -23,7 +23,6 @@
    "@google-cloud/logging-bunyan": "^5.1.0",
    "@overleaf/fetch-utils": "*",
    "@overleaf/o-error": "*",
-    "@sentry/node": "^6.13.2",
    "bunyan": "^1.8.14"
  },
  "devDependencies": {
@@ -1,106 +0,0 @@
-const Serializers = require('./serializers')
-const RATE_LIMIT_MAX_ERRORS = 5
-const RATE_LIMIT_INTERVAL_MS = 60000
-
-class SentryManager {
-  constructor(dsn, options) {
-    this.Sentry = require('@sentry/node')
-    this.Sentry.init({ dsn, ...options })
-    // for rate limiting on sentry reporting
-    this.lastErrorTimeStamp = 0
-    this.lastErrorCount = 0
-  }
-
-  captureExceptionRateLimited(attributes, message) {
-    const now = Date.now()
-    // have we recently reported an error?
-    const recentSentryReport =
-      now - this.lastErrorTimeStamp < RATE_LIMIT_INTERVAL_MS
-    // if so, increment the error count
-    if (recentSentryReport) {
-      this.lastErrorCount++
-    } else {
-      this.lastErrorCount = 0
-      this.lastErrorTimeStamp = now
-    }
-    // only report 5 errors every minute to avoid overload
-    if (this.lastErrorCount < RATE_LIMIT_MAX_ERRORS) {
-      // add a note if the rate limit has been hit
-      const note =
-        this.lastErrorCount + 1 === RATE_LIMIT_MAX_ERRORS
-          ? '(rate limited)'
-          : ''
-      // report the exception
-      this.captureException(attributes, message, `error${note}`)
-    }
-  }
-
-  captureException(attributes, message, level) {
-    // handle case of logger.error "message"
-    if (typeof attributes === 'string') {
-      attributes = { err: new Error(attributes) }
-    }
-
-    // extract any error object
-    let error = Serializers.err(attributes.err || attributes.error)
-
-    // avoid reporting errors twice
-    for (const key in attributes) {
-      const value = attributes[key]
-      if (value instanceof Error && value.reportedToSentry) {
-        return
-      }
-    }
-
-    // include our log message in the error report
-    if (error == null) {
-      if (typeof message === 'string') {
-        error = { message }
-      }
-    } else if (message != null) {
-      attributes.description = message
-    }
-
-    // report the error
-    if (error != null) {
-      // capture attributes and use *_id objects as tags
-      const tags = {}
-      const extra = {}
-      for (const key in attributes) {
-        let value = attributes[key]
-        if (Serializers[key]) {
-          value = Serializers[key](value)
-        }
-        if (key.match(/_id/) && typeof value === 'string') {
-          tags[key] = value
-        }
-        extra[key] = value
-      }
-
-      // OError integration
-      extra.info = error.info
-      delete error.info
-
-      // Sentry wants to receive an Error instance.
-      const errInstance = new Error(error.message)
-      Object.assign(errInstance, error)
-
-      try {
-        // send the error to sentry
-        this.Sentry.captureException(errInstance, { tags, extra, level })
-
-        // put a flag on the errors to avoid reporting them multiple times
-        for (const key in attributes) {
-          const value = attributes[key]
-          if (value instanceof Error) {
-            value.reportedToSentry = true
-          }
-        }
-      } catch (err) {
-        // ignore Sentry errors
-      }
-    }
-  }
-}
-
-module.exports = SentryManager
@@ -8,4 +8,9 @@ chai.use(sinonChai)

 SandboxedModule.configure({
  globals: { Buffer, JSON, console, process },
+  sourceTransformers: {
+    removeNodePrefix: function (source) {
+      return source.replace(/require\(['"]node:/g, "require('")
+    },
+  },
 })
@@ -1,5 +1,5 @@
-const Path = require('path')
-const { promisify } = require('util')
+const Path = require('node:path')
+const { promisify } = require('node:util')
 const SandboxedModule = require('sandboxed-module')
 const sinon = require('sinon')
 const { expect } = require('chai')
@@ -1,7 +1,7 @@
 const SandboxedModule = require('sandboxed-module')
 const bunyan = require('bunyan')
 const { expect } = require('chai')
-const path = require('path')
+const path = require('node:path')
 const sinon = require('sinon')

 const MODULE_PATH = path.join(__dirname, '../../logging-manager.js')
@@ -43,20 +43,14 @@ describe('LoggingManager', function () {
        .stub()
        .returns(this.GCEMetadataLogLevelChecker),
    }
-    this.SentryManager = {
-      captureException: sinon.stub(),
-      captureExceptionRateLimited: sinon.stub(),
-    }
    this.LoggingManager = SandboxedModule.require(MODULE_PATH, {
      requires: {
        bunyan: this.Bunyan,
        './log-level-checker': this.LogLevelChecker,
-        './sentry-manager': sinon.stub().returns(this.SentryManager),
      },
    })
    this.loggerName = 'test'
    this.logger = this.LoggingManager.initialize(this.loggerName)
-    this.logger.initializeErrorReporting('test_dsn')
  })

  afterEach(function () {
@@ -160,13 +154,6 @@ describe('LoggingManager', function () {
    })
  })

-  describe('logger.error', function () {
-    it('should report errors to Sentry', function () {
-      this.logger.error({ foo: 'bar' }, 'message')
-      expect(this.SentryManager.captureExceptionRateLimited).to.have.been.called
-    })
-  })
-
  describe('ringbuffer', function () {
    beforeEach(function () {
      this.logBufferMock = [
@@ -1,247 +0,0 @@
-const Path = require('path')
-const SandboxedModule = require('sandboxed-module')
-const { expect } = require('chai')
-const sinon = require('sinon')
-
-const MODULE_PATH = Path.join(__dirname, '../../sentry-manager.js')
-
-describe('SentryManager', function () {
-  beforeEach(function () {
-    this.clock = sinon.useFakeTimers(Date.now())
-    this.Sentry = {
-      init: sinon.stub(),
-      captureException: sinon.stub(),
-    }
-    this.SentryManager = SandboxedModule.require(MODULE_PATH, {
-      requires: {
-        '@sentry/node': this.Sentry,
-      },
-    })
-    this.sentryManager = new this.SentryManager('test_dsn')
-  })
-
-  afterEach(function () {
-    this.clock.restore()
-  })
-
-  describe('captureExceptionRateLimited', function () {
-    it('should report a single error to sentry', function () {
-      this.sentryManager.captureExceptionRateLimited({ foo: 'bar' }, 'message')
-      expect(this.Sentry.captureException).to.have.been.calledOnce
-    })
-
-    it('should report the same error to sentry only once', function () {
-      const error1 = new Error('this is the error')
-      this.sentryManager.captureExceptionRateLimited(
-        { foo: error1 },
-        'first message'
-      )
-      this.sentryManager.captureExceptionRateLimited(
-        { bar: error1 },
-        'second message'
-      )
-      expect(this.Sentry.captureException).to.have.been.calledOnce
-    })
-
-    it('should report two different errors to sentry individually', function () {
-      const error1 = new Error('this is the error')
-      const error2 = new Error('this is the error')
-      this.sentryManager.captureExceptionRateLimited(
-        { foo: error1 },
-        'first message'
-      )
-      this.sentryManager.captureExceptionRateLimited(
-        { bar: error2 },
-        'second message'
-      )
-      expect(this.Sentry.captureException).to.have.been.calledTwice
-    })
-
-    it('for multiple errors should only report a maximum of 5 errors to sentry', function () {
-      for (let i = 0; i < 10; i++) {
-        this.sentryManager.captureExceptionRateLimited(
-          { foo: 'bar' },
-          'message'
-        )
-      }
-      expect(this.Sentry.captureException).to.have.callCount(5)
-    })
-
-    it('for multiple errors with a minute delay should report 10 errors to sentry', function () {
-      for (let i = 0; i < 10; i++) {
-        this.sentryManager.captureExceptionRateLimited(
-          { foo: 'bar' },
-          'message'
-        )
-      }
-      expect(this.Sentry.captureException).to.have.callCount(5)
-
-      // allow a minute to pass
-      this.clock.tick(61 * 1000)
-
-      for (let i = 0; i < 10; i++) {
-        this.sentryManager.captureExceptionRateLimited(
-          { foo: 'bar' },
-          'message'
-        )
-      }
-      expect(this.Sentry.captureException).to.have.callCount(10)
-    })
-  })
-
-  describe('captureException', function () {
-    it('should remove the path from fs errors', function () {
-      const fsError = new Error(
-        "Error: ENOENT: no such file or directory, stat '/tmp/3279b8d0-da10-11e8-8255-efd98985942b'"
-      )
-      fsError.path = '/tmp/3279b8d0-da10-11e8-8255-efd98985942b'
-      this.sentryManager.captureException({ err: fsError }, 'message', 'error')
-      expect(this.Sentry.captureException).to.have.been.calledWith(
-        sinon.match.has(
-          'message',
-          'Error: ENOENT: no such file or directory, stat'
-        )
-      )
-    })
-
-    it('should sanitize error', function () {
-      const err = {
-        name: 'CustomError',
-        message: 'hello',
-        _oErrorTags: [{ stack: 'here:1', info: { one: 1 } }],
-        stack: 'here:0',
-        info: { key: 'value' },
-        code: 42,
-        signal: 9,
-        path: '/foo',
-      }
-      this.sentryManager.captureException({ err }, 'message', 'error')
-      const expectedErr = {
-        name: 'CustomError',
-        message: 'hello',
-        stack: 'here:0\nhere:1',
-        code: 42,
-        signal: 9,
-        path: '/foo',
-      }
-      expect(this.Sentry.captureException).to.have.been.calledWith(
-        sinon.match(expectedErr),
-        sinon.match({
-          tags: sinon.match.any,
-          level: sinon.match.any,
-          extra: {
-            description: 'message',
-            info: sinon.match({
-              one: 1,
-              key: 'value',
-            }),
-          },
-        })
-      )
-      // Chai is very picky with comparing Error instances. Go the long way of comparing all the fields manually.
-      const gotErr = this.Sentry.captureException.args[0][0]
-      for (const [key, wanted] of Object.entries(expectedErr)) {
-        expect(gotErr).to.have.property(key, wanted)
-      }
-    })
-    it('should sanitize request', function () {
-      const req = {
-        ip: '1.2.3.4',
-        method: 'GET',
-        url: '/foo',
-        headers: {
-          referer: 'abc',
-          'content-length': 1337,
-          'user-agent': 'curl',
-          authorization: '42',
-        },
-      }
-      this.sentryManager.captureException({ req }, 'message', 'error')
-      const expectedReq = {
-        remoteAddress: '1.2.3.4',
-        method: 'GET',
-        url: '/foo',
-        headers: {
-          referer: 'abc',
-          'content-length': 1337,
-          'user-agent': 'curl',
-        },
-      }
-      expect(this.Sentry.captureException).to.have.been.calledWith(
-        sinon.match({
-          message: 'message',
-        }),
-        sinon.match({
-          tags: sinon.match.any,
-          level: sinon.match.any,
-          extra: {
-            info: sinon.match.any,
-            req: expectedReq,
-          },
-        })
-      )
-      expect(this.Sentry.captureException.args[0][1].extra.req).to.deep.equal(
-        expectedReq
-      )
-    })
-    it('should sanitize response', function () {
-      const res = {
-        statusCode: 417,
-        body: Buffer.from('foo'),
-        getHeader(key) {
-          expect(key).to.be.oneOf(['content-length'])
-          if (key === 'content-length') return 1337
-        },
-      }
-      this.sentryManager.captureException({ res }, 'message', 'error')
-      const expectedRes = {
-        statusCode: 417,
-        headers: {
-          'content-length': 1337,
-        },
-      }
-      expect(this.Sentry.captureException).to.have.been.calledWith(
-        sinon.match({
-          message: 'message',
-        }),
-        sinon.match({
-          tags: sinon.match.any,
-          level: sinon.match.any,
-          extra: {
-            info: sinon.match.any,
-            res: expectedRes,
-          },
-        })
-      )
-      expect(this.Sentry.captureException.args[0][1].extra.res).to.deep.equal(
-        expectedRes
-      )
-    })
-
-    describe('reportedToSentry', function () {
-      it('should mark the error as reported to sentry', function () {
-        const err = new Error()
-        this.sentryManager.captureException({ err }, 'message')
-        expect(this.Sentry.captureException).to.have.been.called
-        expect(err.reportedToSentry).to.equal(true)
-      })
-
-      it('should mark two errors as reported to sentry', function () {
-        const err1 = new Error()
-        const err2 = new Error()
-        this.sentryManager.captureException({ err: err1, err2 }, 'message')
-        expect(this.Sentry.captureException).to.have.been.called
-        expect(err1.reportedToSentry).to.equal(true)
-        expect(err2.reportedToSentry).to.equal(true)
-      })
-
-      it('should not mark arbitrary objects as reported to sentry', function () {
-        const err = new Error()
-        const ctx = { foo: 'bar' }
-        this.sentryManager.captureException({ err, ctx }, 'message')
-        expect(this.Sentry.captureException).to.have.been.called
-        expect(ctx.reportedToSentry).not.to.exist
-      })
-    })
-  })
-})
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ metrics
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -88,7 +88,7 @@ function initializeProfileAgent() {
 }

 function initializePrometheus() {
-  const os = require('os')
+  const os = require('node:os')
  const promClient = require('prom-client')
  promClient.register.setDefaultLabels({ app: APP_NAME, host: os.hostname() })
  promClient.collectDefaultMetrics({ timeout: 5000, prefix: '' })
@@ -6,8 +6,8 @@
 * logged along with the corresponding information from /proc/net/tcp.
 */

-const fs = require('fs')
-const diagnosticsChannel = require('diagnostics_channel')
+const fs = require('node:fs')
+const diagnosticsChannel = require('node:diagnostics_channel')

 const SOCKET_MONITOR_INTERVAL = 60 * 1000
 // set the threshold for logging leaked sockets in minutes, defaults to 15
@@ -11,13 +11,13 @@ const seconds = 1000
 // In Node 0.10 the default is 5, which means only 5 open connections at one.
 // Node 0.12 has a default of Infinity. Make sure we have no limit set,
 // regardless of Node version.
-require('http').globalAgent.maxSockets = Infinity
-require('https').globalAgent.maxSockets = Infinity
+require('node:http').globalAgent.maxSockets = Infinity
+require('node:https').globalAgent.maxSockets = Infinity

-const SOCKETS_HTTP = require('http').globalAgent.sockets
-const SOCKETS_HTTPS = require('https').globalAgent.sockets
-const FREE_SOCKETS_HTTP = require('http').globalAgent.freeSockets
-const FREE_SOCKETS_HTTPS = require('https').globalAgent.freeSockets
+const SOCKETS_HTTP = require('node:http').globalAgent.sockets
+const SOCKETS_HTTPS = require('node:https').globalAgent.sockets
+const FREE_SOCKETS_HTTP = require('node:http').globalAgent.freeSockets
+const FREE_SOCKETS_HTTPS = require('node:https').globalAgent.freeSockets

 // keep track of set gauges and reset them in the next collection cycle
 const SEEN_HOSTS_HTTP = new Set()
@@ -1,6 +1,6 @@
-const { promisify } = require('util')
-const os = require('os')
-const http = require('http')
+const { promisify } = require('node:util')
+const os = require('node:os')
+const http = require('node:http')
 const { expect } = require('chai')
 const Metrics = require('../..')

@@ -316,7 +316,7 @@ async function checkSummaryValues(key, values) {
  for (const quantile of Object.keys(values)) {
    expect(found[quantile]).to.be.within(
      values[quantile] - 5,
-      values[quantile] + 5,
+      values[quantile] + 15,
      `quantile: ${quantile}`
    )
  }
@@ -5,7 +5,7 @@
 */
 const chai = require('chai')
 const { expect } = chai
-const path = require('path')
+const path = require('node:path')
 const modulePath = path.join(__dirname, '../../../event_loop.js')
 const SandboxedModule = require('sandboxed-module')
 const sinon = require('sinon')
@@ -1,4 +1,4 @@
-const Path = require('path')
+const Path = require('node:path')
 const SandboxedModule = require('sandboxed-module')
 const sinon = require('sinon')

@@ -0,0 +1 @@
+node_modules/
@@ -0,0 +1,3 @@
+
+# managed by monorepo$ bin/update_build_scripts
+.npmrc
@@ -0,0 +1 @@
+20.18.0
@@ -1,9 +1,11 @@
-const { ObjectId } = require('mongodb-legacy')
-const {
-  db,
-  waitForDb,
-  READ_PREFERENCE_SECONDARY,
-} = require('../../app/src/infrastructure/mongodb')
+// @ts-check
+/* eslint-disable no-console */
+const { ObjectId, ReadPreference } = require('mongodb')
+
+const READ_PREFERENCE_SECONDARY =
+  process.env.MONGO_HAS_SECONDARIES === 'true'
+    ? ReadPreference.secondary.mode
+    : ReadPreference.secondaryPreferred.mode

 const ONE_MONTH_IN_MS = 1000 * 60 * 60 * 24 * 31
 let ID_EDGE_PAST
@@ -15,16 +17,38 @@ let BATCH_RANGE_START
 let BATCH_RANGE_END
 let BATCH_MAX_TIME_SPAN_IN_MS

+/**
+ * @typedef {import("mongodb").Collection} Collection
+ * @typedef {import("mongodb-legacy").Collection} LegacyCollection
+ * @typedef {import("mongodb").Document} Document
+ * @typedef {import("mongodb").FindOptions} FindOptions
+ * @typedef {import("mongodb").UpdateFilter<Document>} UpdateDocument
+ */
+
+/**
+ * @typedef {Object} BatchedUpdateOptions
+ * @property {string} [BATCH_DESCENDING]
+ * @property {string} [BATCH_LAST_ID]
+ * @property {string} [BATCH_MAX_TIME_SPAN_IN_MS]
+ * @property {string} [BATCH_RANGE_END]
+ * @property {string} [BATCH_RANGE_START]
+ * @property {string} [BATCH_SIZE]
+ * @property {string} [VERBOSE_LOGGING]
+ */
+
+/**
+ * @param {BatchedUpdateOptions} options
+ */
 function refreshGlobalOptionsForBatchedUpdate(options = {}) {
  options = Object.assign({}, options, process.env)

  BATCH_DESCENDING = options.BATCH_DESCENDING === 'true'
-  BATCH_SIZE = parseInt(options.BATCH_SIZE, 10) || 1000
+  BATCH_SIZE = parseInt(options.BATCH_SIZE || '1000', 10) || 1000
  VERBOSE_LOGGING = options.VERBOSE_LOGGING === 'true'
  if (options.BATCH_LAST_ID) {
-    BATCH_RANGE_START = new ObjectId(options.BATCH_LAST_ID)
+    BATCH_RANGE_START = objectIdFromInput(options.BATCH_LAST_ID)
  } else if (options.BATCH_RANGE_START) {
-    BATCH_RANGE_START = new ObjectId(options.BATCH_RANGE_START)
+    BATCH_RANGE_START = objectIdFromInput(options.BATCH_RANGE_START)
  } else {
    if (BATCH_DESCENDING) {
      BATCH_RANGE_START = ID_EDGE_FUTURE
@@ -32,10 +56,12 @@ function refreshGlobalOptionsForBatchedUpdate(options = {}) {
      BATCH_RANGE_START = ID_EDGE_PAST
    }
  }
-  BATCH_MAX_TIME_SPAN_IN_MS =
-    parseInt(options.BATCH_MAX_TIME_SPAN_IN_MS, 10) || ONE_MONTH_IN_MS
+  BATCH_MAX_TIME_SPAN_IN_MS = parseInt(
+    options.BATCH_MAX_TIME_SPAN_IN_MS || ONE_MONTH_IN_MS.toString(),
+    10
+  )
  if (options.BATCH_RANGE_END) {
-    BATCH_RANGE_END = new ObjectId(options.BATCH_RANGE_END)
+    BATCH_RANGE_END = objectIdFromInput(options.BATCH_RANGE_END)
  } else {
    if (BATCH_DESCENDING) {
      BATCH_RANGE_END = ID_EDGE_PAST
@@ -45,23 +71,32 @@ function refreshGlobalOptionsForBatchedUpdate(options = {}) {
  }
 }

-async function getNextBatch({
+/**
+ * @param {Collection | LegacyCollection} collection
+ * @param {Document} query
+ * @param {ObjectId} start
+ * @param {ObjectId} end
+ * @param {Document} projection
+ * @param {FindOptions} findOptions
+ * @return {Promise<Array<Document>>}
+ */
+async function getNextBatch(
  collection,
  query,
  start,
  end,
  projection,
-  findOptions,
-}) {
+  findOptions
+) {
  if (BATCH_DESCENDING) {
    query._id = {
      $gt: end,
-      $lt: start,
+      $lte: start,
    }
  } else {
    query._id = {
      $gt: start,
-      $lt: end,
+      $lte: end,
    }
  }
  return await collection
@@ -72,21 +107,61 @@ async function getNextBatch({
    .toArray()
 }

+/**
+ * @param {Collection | LegacyCollection} collection
+ * @param {Array<Document>} nextBatch
+ * @param {UpdateDocument} update
+ * @return {Promise<void>}
+ */
 async function performUpdate(collection, nextBatch, update) {
-  return collection.updateMany(
+  await collection.updateMany(
    { _id: { $in: nextBatch.map(entry => entry._id) } },
    update
  )
 }

+/**
+ * @param {string} input
+ * @return {ObjectId}
+ */
+function objectIdFromInput(input) {
+  if (input.includes('T')) {
+    const t = new Date(input).getTime()
+    if (Number.isNaN(t)) throw new Error(`${input} is not a valid date`)
+    return objectIdFromMs(t)
+  } else {
+    return new ObjectId(input)
+  }
+}
+
+/**
+ * @param {ObjectId} objectId
+ * @return {string}
+ */
+function renderObjectId(objectId) {
+  return `${objectId} (${objectId.getTimestamp().toISOString()})`
+}
+
+/**
+ * @param {number} ms
+ * @return {ObjectId}
+ */
 function objectIdFromMs(ms) {
  return ObjectId.createFromTime(ms / 1000)
 }

+/**
+ * @param {ObjectId} id
+ * @return {number}
+ */
 function getMsFromObjectId(id) {
  return id.getTimestamp().getTime()
 }

+/**
+ * @param {ObjectId} start
+ * @return {ObjectId}
+ */
 function getNextEnd(start) {
  let end
  if (BATCH_DESCENDING) {
@@ -103,6 +178,10 @@ function getNextEnd(start) {
  return end
 }

+/**
+ * @param {Collection | LegacyCollection} collection
+ * @return {Promise<ObjectId|null>}
+ */
 async function getIdEdgePast(collection) {
  const [first] = await collection
    .find({})
@@ -111,24 +190,32 @@ async function getIdEdgePast(collection) {
    .limit(1)
    .toArray()
  if (!first) return null
-  // Go 1s further into the past in order to include the first entry via
+  // Go one second further into the past in order to include the first entry via
  // first._id > ID_EDGE_PAST
  return objectIdFromMs(Math.max(0, getMsFromObjectId(first._id) - 1000))
 }

+/**
+ * @param {Collection | LegacyCollection} collection
+ * @param {Document} query
+ * @param {UpdateDocument | ((batch: Array<Document>) => Promise<void>)} update
+ * @param {Document} [projection]
+ * @param {FindOptions} [findOptions]
+ * @param {BatchedUpdateOptions} [batchedUpdateOptions]
+ */
 async function batchedUpdate(
-  collectionName,
+  collection,
  query,
  update,
  projection,
  findOptions,
  batchedUpdateOptions
 ) {
-  await waitForDb()
-  const collection = db[collectionName]
  ID_EDGE_PAST = await getIdEdgePast(collection)
  if (!ID_EDGE_PAST) {
-    console.warn(`The collection ${collectionName} appears to be empty.`)
+    console.warn(
+      `The collection ${collection.collectionName} appears to be empty.`
+    )
    return 0
  }
  refreshGlobalOptionsForBatchedUpdate(batchedUpdateOptions)
@@ -143,14 +230,14 @@ async function batchedUpdate(

  while (start !== BATCH_RANGE_END) {
    let end = getNextEnd(start)
-    nextBatch = await getNextBatch({
+    nextBatch = await getNextBatch(
      collection,
      query,
      start,
      end,
      projection,
-      findOptions,
-    })
+      findOptions
+    )
    if (nextBatch.length > 0) {
      end = nextBatch[nextBatch.length - 1]._id
      updated += nextBatch.length
@@ -162,7 +249,7 @@ async function batchedUpdate(
          )}`
        )
      } else {
-        console.error(`Running update on batch ending ${end}`)
+        console.error(`Running update on batch ending ${renderObjectId(end)}`)
      }

      if (typeof update === 'function') {
@@ -171,20 +258,36 @@ async function batchedUpdate(
        await performUpdate(collection, nextBatch, update)
      }
    }
-    console.error(`Completed batch ending ${end}`)
+    console.error(`Completed batch ending ${renderObjectId(end)}`)
    start = end
  }
  return updated
 }

+/**
+ * @param {Collection | LegacyCollection} collection
+ * @param {Document} query
+ * @param {UpdateDocument | ((batch: Array<Object>) => Promise<void>)} update
+ * @param {Document} [projection]
+ * @param {FindOptions} [findOptions]
+ * @param {BatchedUpdateOptions} [batchedUpdateOptions]
+ */
 function batchedUpdateWithResultHandling(
  collection,
  query,
  update,
  projection,
-  options
+  findOptions,
+  batchedUpdateOptions
 ) {
-  batchedUpdate(collection, query, update, projection, options)
+  batchedUpdate(
+    collection,
+    query,
+    update,
+    projection,
+    findOptions,
+    batchedUpdateOptions
+  )
    .then(processed => {
      console.error({ processed })
      process.exit(0)
@@ -196,6 +299,9 @@ function batchedUpdateWithResultHandling(
 }

 module.exports = {
+  READ_PREFERENCE_SECONDARY,
+  objectIdFromInput,
+  renderObjectId,
  batchedUpdate,
  batchedUpdateWithResultHandling,
 }
@@ -0,0 +1,10 @@
+mongo-utils
+--dependencies=None
+--docker-repos=gcr.io/overleaf-ops
+--env-add=
+--env-pass-through=
+--esmock-loader=False
+--is-library=True
+--node-version=20.18.0
+--public-repo=False
+--script-version=4.5.0
@@ -0,0 +1,30 @@
+{
+  "name": "@overleaf/mongo-utils",
+  "version": "0.0.1",
+  "description": "utilities to help working with mongo",
+  "main": "index.js",
+  "scripts": {
+    "test": "npm run lint && npm run format && npm run types:check && npm run test:unit",
+    "test:unit": "mocha --exit test/**/*.{js,cjs}",
+    "lint": "eslint --ext .js --ext .cjs --ext .ts --max-warnings 0 --format unix .",
+    "lint:fix": "eslint --fix --ext .js --ext .cjs --ext .ts .",
+    "format": "prettier --list-different $PWD/'**/*.{js,cjs,ts}'",
+    "format:fix": "prettier --write $PWD/'**/*.{js,cjs,ts}'",
+    "test:ci": "npm run test:unit",
+    "types:check": "tsc --noEmit"
+  },
+  "author": "Overleaf (https://www.overleaf.com)",
+  "license": "AGPL-3.0-only",
+  "dependencies": {
+    "mongodb": "6.10.0",
+    "mongodb-legacy": "6.1.3"
+  },
+  "devDependencies": {
+    "chai": "^4.3.6",
+    "mocha": "^10.2.0",
+    "sandboxed-module": "^2.0.4",
+    "sinon": "^9.2.4",
+    "sinon-chai": "^3.7.0",
+    "typescript": "^5.0.4"
+  }
+}
@@ -0,0 +1,11 @@
+const chai = require('chai')
+const sinonChai = require('sinon-chai')
+const SandboxedModule = require('sandboxed-module')
+
+// Chai configuration
+chai.should()
+chai.use(sinonChai)
+
+SandboxedModule.configure({
+  globals: { Buffer, JSON, console, process },
+})
@@ -0,0 +1,7 @@
+{
+  "extends": "../../tsconfig.backend.json",
+  "include": [
+    "**/*.js",
+    "**/*.cjs"
+  ]
+}
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ o-error
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -70,7 +70,7 @@ sayHi3(43, (err, result) => {
  }
 })

-const promisify = require('util').promisify
+const promisify = require('node:util').promisify
 demoDatabase.findUserAsync = promisify(demoDatabase.findUser)

 async function sayHi4NoHandling(userId) {
@@ -1,5 +1,5 @@
 const { expect } = require('chai')
-const { promisify } = require('util')
+const { promisify } = require('node:util')

 const OError = require('..')

@@ -23,7 +23,7 @@ exports.expectError = function OErrorExpectError(e, expected) {
  ).to.be.true

  expect(
-    require('util').types.isNativeError(e),
+    require('node:util').types.isNativeError(e),
    'error should be recognised by util.types.isNativeError'
  ).to.be.true

@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ object-persistor
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -24,7 +24,8 @@
    "@overleaf/logger": "*",
    "@overleaf/metrics": "*",
    "@overleaf/o-error": "*",
-    "aws-sdk": "^2.718.0",
+    "@overleaf/stream-utils": "*",
+    "aws-sdk": "^2.1691.0",
    "fast-crc32c": "overleaf/node-fast-crc32c#aae6b2a4c7a7a159395df9cc6c38dfde702d6f51",
    "glob": "^7.1.6",
    "range-parser": "^1.2.1",
@@ -35,7 +36,7 @@
    "chai-as-promised": "^7.1.1",
    "mocha": "^10.2.0",
    "mock-fs": "^5.2.0",
-    "mongodb": "^6.1.0",
+    "mongodb": "6.10.0",
    "sandboxed-module": "^2.0.4",
    "sinon": "^9.2.4",
    "sinon-chai": "^3.7.0",
@@ -1,6 +1,12 @@
 const { NotImplementedError } = require('./Errors')

 module.exports = class AbstractPersistor {
+  /**
+   * @param location
+   * @param target
+   * @param {string} source
+   * @return {Promise<void>}
+   */
  async sendFile(location, target, source) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'sendFile',
@@ -10,6 +16,13 @@ module.exports = class AbstractPersistor {
    })
  }

+  /**
+   * @param location
+   * @param target
+   * @param {NodeJS.ReadableStream} sourceStream
+   * @param {Object} opts
+   * @return {Promise<void>}
+   */
  async sendStream(location, target, sourceStream, opts = {}) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'sendStream',
@@ -22,12 +35,12 @@ module.exports = class AbstractPersistor {
  /**
   * @param location
   * @param name
-   * @param {Object} opts
-   * @param {Number} opts.start
-   * @param {Number} opts.end
-   * @return {Promise<Readable>}
+   * @param {Object} [opts]
+   * @param {Number} [opts.start]
+   * @param {Number} [opts.end]
+   * @return {Promise<NodeJS.ReadableStream>}
   */
-  async getObjectStream(location, name, opts) {
+  async getObjectStream(location, name, opts = {}) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'getObjectStream',
      location,
@@ -36,6 +49,11 @@ module.exports = class AbstractPersistor {
    })
  }

+  /**
+   * @param {string} location
+   * @param {string} name
+   * @return {Promise<string>}
+   */
  async getRedirectUrl(location, name) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'getRedirectUrl',
@@ -44,7 +62,13 @@ module.exports = class AbstractPersistor {
    })
  }

-  async getObjectSize(location, name) {
+  /**
+   * @param {string} location
+   * @param {string} name
+   * @param {Object} opts
+   * @return {Promise<number>}
+   */
+  async getObjectSize(location, name, opts) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'getObjectSize',
      location,
@@ -52,7 +76,13 @@ module.exports = class AbstractPersistor {
    })
  }

-  async getObjectMd5Hash(location, name) {
+  /**
+   * @param {string} location
+   * @param {string} name
+   * @param {Object} opts
+   * @return {Promise<string>}
+   */
+  async getObjectMd5Hash(location, name, opts) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'getObjectMd5Hash',
      location,
@@ -60,7 +90,14 @@ module.exports = class AbstractPersistor {
    })
  }

-  async copyObject(location, fromName, toName) {
+  /**
+   * @param {string} location
+   * @param {string} fromName
+   * @param {string} toName
+   * @param {Object} opts
+   * @return {Promise<void>}
+   */
+  async copyObject(location, fromName, toName, opts) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'copyObject',
      location,
@@ -69,6 +106,11 @@ module.exports = class AbstractPersistor {
    })
  }

+  /**
+   * @param {string} location
+   * @param {string} name
+   * @return {Promise<void>}
+   */
  async deleteObject(location, name) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'deleteObject',
@@ -77,7 +119,13 @@ module.exports = class AbstractPersistor {
    })
  }

-  async deleteDirectory(location, name) {
+  /**
+   * @param {string} location
+   * @param {string} name
+   * @param {string} [continuationToken]
+   * @return {Promise<void>}
+   */
+  async deleteDirectory(location, name, continuationToken) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'deleteDirectory',
      location,
@@ -85,7 +133,13 @@ module.exports = class AbstractPersistor {
    })
  }

-  async checkIfObjectExists(location, name) {
+  /**
+   * @param {string} location
+   * @param {string} name
+   * @param {Object} opts
+   * @return {Promise<boolean>}
+   */
+  async checkIfObjectExists(location, name, opts) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'checkIfObjectExists',
      location,
@@ -93,7 +147,13 @@ module.exports = class AbstractPersistor {
    })
  }

-  async directorySize(location, name) {
+  /**
+   * @param {string} location
+   * @param {string} name
+   * @param {string} [continuationToken]
+   * @return {Promise<number>}
+   */
+  async directorySize(location, name, continuationToken) {
    throw new NotImplementedError('method not implemented in persistor', {
      method: 'directorySize',
      location,
@@ -5,6 +5,8 @@ class WriteError extends OError {}
 class ReadError extends OError {}
 class SettingsError extends OError {}
 class NotImplementedError extends OError {}
+class AlreadyWrittenError extends OError {}
+class NoKEKMatchedError extends OError {}

 module.exports = {
  NotFoundError,
@@ -12,4 +14,6 @@ module.exports = {
  ReadError,
  SettingsError,
  NotImplementedError,
+  AlreadyWrittenError,
+  NoKEKMatchedError,
 }
@@ -1,20 +1,26 @@
-const crypto = require('crypto')
-const fs = require('fs')
-const fsPromises = require('fs/promises')
+const crypto = require('node:crypto')
+const fs = require('node:fs')
+const fsPromises = require('node:fs/promises')
 const globCallbacks = require('glob')
-const Path = require('path')
-const { PassThrough } = require('stream')
-const { pipeline } = require('stream/promises')
-const { promisify } = require('util')
+const Path = require('node:path')
+const { PassThrough } = require('node:stream')
+const { pipeline } = require('node:stream/promises')
+const { promisify } = require('node:util')

 const AbstractPersistor = require('./AbstractPersistor')
-const { ReadError, WriteError } = require('./Errors')
+const { ReadError, WriteError, NotImplementedError } = require('./Errors')
 const PersistorHelper = require('./PersistorHelper')

 const glob = promisify(globCallbacks)

 module.exports = class FSPersistor extends AbstractPersistor {
  constructor(settings = {}) {
+    if (settings.storageClass) {
+      throw new NotImplementedError(
+        'FS backend does not support storage classes'
+      )
+    }
+
    super()
    this.useSubdirectories = Boolean(settings.useSubdirectories)
  }
@@ -36,6 +42,14 @@ module.exports = class FSPersistor extends AbstractPersistor {
  }

  async sendStream(location, target, sourceStream, opts = {}) {
+    if (opts.ifNoneMatch === '*') {
+      // The standard library only has fs.rename(), which does not support exclusive flags.
+      // Refuse to act on this write operation.
+      throw new NotImplementedError(
+        'Overwrite protection required by caller, but it is not available is FS backend. Configure GCS or S3 backend instead, get in touch with support for further information.'
+      )
+    }
+
    const targetPath = this._getFsPath(location, target)

    try {
@@ -55,7 +69,7 @@ module.exports = class FSPersistor extends AbstractPersistor {
      throw PersistorHelper.wrapError(
        err,
        'failed to write stream',
-        { location, target },
+        { location, target, ifNoneMatch: opts.ifNoneMatch },
        WriteError
      )
    }
@@ -63,6 +77,11 @@ module.exports = class FSPersistor extends AbstractPersistor {

  // opts may be {start: Number, end: Number}
  async getObjectStream(location, name, opts = {}) {
+    if (opts.autoGunzip) {
+      throw new NotImplementedError(
+        'opts.autoGunzip is not supported by FS backend. Configure GCS or S3 backend instead, get in touch with support for further information.'
+      )
+    }
    const observer = new PersistorHelper.ObserverStream({
      metric: 'fs.ingress', // ingress to us from disk
      bucket: location,
@@ -1,17 +1,28 @@
-const fs = require('fs')
-const { pipeline } = require('stream/promises')
-const { PassThrough } = require('stream')
+const fs = require('node:fs')
+const { pipeline } = require('node:stream/promises')
+const { PassThrough } = require('node:stream')
 const { Storage, IdempotencyStrategy } = require('@google-cloud/storage')
-const { WriteError, ReadError, NotFoundError } = require('./Errors')
+const {
+  WriteError,
+  ReadError,
+  NotFoundError,
+  NotImplementedError,
+} = require('./Errors')
 const asyncPool = require('tiny-async-pool')
 const AbstractPersistor = require('./AbstractPersistor')
 const PersistorHelper = require('./PersistorHelper')
 const Logger = require('@overleaf/logger')
+const zlib = require('node:zlib')

 module.exports = class GcsPersistor extends AbstractPersistor {
  constructor(settings) {
-    super()
+    if (settings.storageClass) {
+      throw new NotImplementedError(
+        'Use default bucket class for GCS instead of settings.storageClass'
+      )
+    }

+    super()
    this.settings = settings

    // endpoint settings will be null by default except for tests
@@ -78,10 +89,14 @@ module.exports = class GcsPersistor extends AbstractPersistor {
        writeOptions.metadata = writeOptions.metadata || {}
        writeOptions.metadata.contentEncoding = opts.contentEncoding
      }
+      const fileOptions = {}
+      if (opts.ifNoneMatch === '*') {
+        fileOptions.generation = 0
+      }

      const uploadStream = this.storage
        .bucket(bucketName)
-        .file(key)
+        .file(key, fileOptions)
        .createWriteStream(writeOptions)

      await pipeline(readStream, observer, uploadStream)
@@ -97,7 +112,7 @@ module.exports = class GcsPersistor extends AbstractPersistor {
      throw PersistorHelper.wrapError(
        err,
        'upload to GCS failed',
-        { bucketName, key },
+        { bucketName, key, ifNoneMatch: opts.ifNoneMatch },
        WriteError
      )
    }
@@ -113,12 +128,14 @@ module.exports = class GcsPersistor extends AbstractPersistor {
      .file(key)
      .createReadStream({ decompress: false, ...opts })

+    let contentEncoding
    try {
      await new Promise((resolve, reject) => {
        stream.on('response', res => {
          switch (res.statusCode) {
            case 200: // full response
            case 206: // partial response
+              contentEncoding = res.headers['content-encoding']
              return resolve()
            case 404:
              return reject(new NotFoundError())
@@ -139,7 +156,11 @@ module.exports = class GcsPersistor extends AbstractPersistor {
    }
    // Return a PassThrough stream with a minimal interface. It will buffer until the caller starts reading. It will emit errors from the source stream (Stream.pipeline passes errors along).
    const pass = new PassThrough()
-    pipeline(stream, observer, pass).catch(() => {})
+    const transformer = []
+    if (contentEncoding === 'gzip' && opts.autoGunzip) {
+      transformer.push(zlib.createGunzip())
+    }
+    pipeline(stream, observer, ...transformer, pass).catch(() => {})
    return pass
  }

@@ -176,7 +197,7 @@ module.exports = class GcsPersistor extends AbstractPersistor {
        .bucket(bucketName)
        .file(key)
        .getMetadata()
-      return metadata.size
+      return parseInt(metadata.size, 10)
    } catch (err) {
      throw PersistorHelper.wrapError(
        err,
@@ -285,7 +306,10 @@ module.exports = class GcsPersistor extends AbstractPersistor {
      )
    }

-    return files.reduce((acc, file) => Number(file.metadata.size) + acc, 0)
+    return files.reduce(
+      (acc, file) => parseInt(file.metadata.size, 10) + acc,
+      0
+    )
  }

  async checkIfObjectExists(bucketName, key) {
@@ -1,8 +1,8 @@
 const AbstractPersistor = require('./AbstractPersistor')
 const Logger = require('@overleaf/logger')
 const Metrics = require('@overleaf/metrics')
-const Stream = require('stream')
-const { pipeline } = require('stream/promises')
+const Stream = require('node:stream')
+const { pipeline } = require('node:stream/promises')
 const { NotFoundError, WriteError } = require('./Errors')

 // Persistor that wraps two other persistors. Talks to the 'primary' by default,
@@ -0,0 +1,458 @@
+// @ts-check
+const Crypto = require('node:crypto')
+const Stream = require('node:stream')
+const fs = require('node:fs')
+const { promisify } = require('node:util')
+const { WritableBuffer } = require('@overleaf/stream-utils')
+const { S3Persistor, SSECOptions } = require('./S3Persistor.js')
+const {
+  AlreadyWrittenError,
+  NoKEKMatchedError,
+  NotFoundError,
+  NotImplementedError,
+  ReadError,
+} = require('./Errors')
+const logger = require('@overleaf/logger')
+const Path = require('node:path')
+
+const generateKey = promisify(Crypto.generateKey)
+const hkdf = promisify(Crypto.hkdf)
+
+const AES256_KEY_LENGTH = 32
+
+/**
+ * @typedef {import('aws-sdk').AWSError} AWSError
+ */
+
+/**
+ * @typedef {Object} Settings
+ * @property {boolean} automaticallyRotateDEKEncryption
+ * @property {string} dataEncryptionKeyBucketName
+ * @property {boolean} ignoreErrorsFromDEKReEncryption
+ * @property {(bucketName: string, path: string) => string} pathToProjectFolder
+ * @property {() => Promise<Array<RootKeyEncryptionKey>>} getRootKeyEncryptionKeys
+ */
+
+/**
+ * Helper function to make TS happy when accessing error properties
+ * AWSError is not an actual class, so we cannot use instanceof.
+ * @param {any} err
+ * @return {err is AWSError}
+ */
+function isAWSError(err) {
+  return !!err
+}
+
+/**
+ * @param {any} err
+ * @return {boolean}
+ */
+function isForbiddenError(err) {
+  if (!err || !(err instanceof ReadError || err instanceof NotFoundError)) {
+    return false
+  }
+  const cause = err.cause
+  if (!isAWSError(cause)) return false
+  return cause.statusCode === 403
+}
+
+class RootKeyEncryptionKey {
+  /** @type {Buffer} */
+  #keyEncryptionKey
+  /** @type {Buffer} */
+  #salt
+
+  /**
+   * @param {Buffer} keyEncryptionKey
+   * @param {Buffer} salt
+   */
+  constructor(keyEncryptionKey, salt) {
+    if (keyEncryptionKey.byteLength !== AES256_KEY_LENGTH) {
+      throw new Error(`kek is not ${AES256_KEY_LENGTH} bytes long`)
+    }
+    this.#keyEncryptionKey = keyEncryptionKey
+    this.#salt = salt
+  }
+
+  /**
+   * @param {string} prefix
+   * @return {Promise<SSECOptions>}
+   */
+  async forProject(prefix) {
+    return new SSECOptions(
+      Buffer.from(
+        await hkdf(
+          'sha256',
+          this.#keyEncryptionKey,
+          this.#salt,
+          prefix,
+          AES256_KEY_LENGTH
+        )
+      )
+    )
+  }
+}
+
+class PerProjectEncryptedS3Persistor extends S3Persistor {
+  /** @type {Settings} */
+  #settings
+  /** @type {Promise<Array<RootKeyEncryptionKey>>} */
+  #availableKeyEncryptionKeysPromise
+
+  /**
+   * @param {Settings} settings
+   */
+  constructor(settings) {
+    if (!settings.dataEncryptionKeyBucketName) {
+      throw new Error('settings.dataEncryptionKeyBucketName is missing')
+    }
+    super(settings)
+    this.#settings = settings
+    this.#availableKeyEncryptionKeysPromise = settings
+      .getRootKeyEncryptionKeys()
+      .then(rootKEKs => {
+        if (rootKEKs.length === 0) throw new Error('no root kek provided')
+        return rootKEKs
+      })
+  }
+
+  async ensureKeyEncryptionKeysLoaded() {
+    await this.#availableKeyEncryptionKeysPromise
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @return {{dekPath: string, projectFolder: string}}
+   */
+  #buildProjectPaths(bucketName, path) {
+    const projectFolder = this.#settings.pathToProjectFolder(bucketName, path)
+    const dekPath = Path.join(projectFolder, 'dek')
+    return { projectFolder, dekPath }
+  }
+
+  /**
+   * @param {string} projectFolder
+   * @return {Promise<SSECOptions>}
+   */
+  async #getCurrentKeyEncryptionKey(projectFolder) {
+    const [currentRootKEK] = await this.#availableKeyEncryptionKeysPromise
+    return await currentRootKEK.forProject(projectFolder)
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   */
+  async getDataEncryptionKeySize(bucketName, path) {
+    const { projectFolder, dekPath } = this.#buildProjectPaths(bucketName, path)
+    for (const rootKEK of await this.#availableKeyEncryptionKeysPromise) {
+      const ssecOptions = await rootKEK.forProject(projectFolder)
+      try {
+        return await super.getObjectSize(
+          this.#settings.dataEncryptionKeyBucketName,
+          dekPath,
+          { ssecOptions }
+        )
+      } catch (err) {
+        if (isForbiddenError(err)) continue
+        throw err
+      }
+    }
+    throw new NoKEKMatchedError('no kek matched')
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @return {Promise<CachedPerProjectEncryptedS3Persistor>}
+   */
+  async forProject(bucketName, path) {
+    return new CachedPerProjectEncryptedS3Persistor(
+      this,
+      await this.#getDataEncryptionKeyOptions(bucketName, path)
+    )
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @return {Promise<CachedPerProjectEncryptedS3Persistor>}
+   */
+  async forProjectRO(bucketName, path) {
+    return new CachedPerProjectEncryptedS3Persistor(
+      this,
+      await this.#getExistingDataEncryptionKeyOptions(bucketName, path)
+    )
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @return {Promise<CachedPerProjectEncryptedS3Persistor>}
+   */
+  async generateDataEncryptionKey(bucketName, path) {
+    return new CachedPerProjectEncryptedS3Persistor(
+      this,
+      await this.#generateDataEncryptionKeyOptions(bucketName, path)
+    )
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @return {Promise<SSECOptions>}
+   */
+  async #generateDataEncryptionKeyOptions(bucketName, path) {
+    const dataEncryptionKey = (
+      await generateKey('aes', { length: 256 })
+    ).export()
+    const { projectFolder, dekPath } = this.#buildProjectPaths(bucketName, path)
+    await super.sendStream(
+      this.#settings.dataEncryptionKeyBucketName,
+      dekPath,
+      Stream.Readable.from([dataEncryptionKey]),
+      {
+        // Do not overwrite any objects if already created
+        ifNoneMatch: '*',
+        ssecOptions: await this.#getCurrentKeyEncryptionKey(projectFolder),
+        contentLength: 32,
+      }
+    )
+    return new SSECOptions(dataEncryptionKey)
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @return {Promise<SSECOptions>}
+   */
+  async #getExistingDataEncryptionKeyOptions(bucketName, path) {
+    const { projectFolder, dekPath } = this.#buildProjectPaths(bucketName, path)
+    let res
+    let kekIndex = 0
+    for (const rootKEK of await this.#availableKeyEncryptionKeysPromise) {
+      const ssecOptions = await rootKEK.forProject(projectFolder)
+      try {
+        res = await super.getObjectStream(
+          this.#settings.dataEncryptionKeyBucketName,
+          dekPath,
+          { ssecOptions }
+        )
+        break
+      } catch (err) {
+        if (isForbiddenError(err)) {
+          kekIndex++
+          continue
+        }
+        throw err
+      }
+    }
+    if (!res) throw new NoKEKMatchedError('no kek matched')
+    const buf = new WritableBuffer()
+    await Stream.promises.pipeline(res, buf)
+
+    if (kekIndex !== 0 && this.#settings.automaticallyRotateDEKEncryption) {
+      const ssecOptions = await this.#getCurrentKeyEncryptionKey(projectFolder)
+      try {
+        await super.sendStream(
+          this.#settings.dataEncryptionKeyBucketName,
+          dekPath,
+          Stream.Readable.from([buf.getContents()]),
+          { ssecOptions }
+        )
+      } catch (err) {
+        if (this.#settings.ignoreErrorsFromDEKReEncryption) {
+          logger.warn({ err, dekPath }, 'failed to persist re-encrypted DEK')
+        } else {
+          throw err
+        }
+      }
+    }
+
+    return new SSECOptions(buf.getContents())
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @return {Promise<SSECOptions>}
+   */
+  async #getDataEncryptionKeyOptions(bucketName, path) {
+    try {
+      return await this.#getExistingDataEncryptionKeyOptions(bucketName, path)
+    } catch (err) {
+      if (err instanceof NotFoundError) {
+        try {
+          return await this.#generateDataEncryptionKeyOptions(bucketName, path)
+        } catch (err2) {
+          if (err2 instanceof AlreadyWrittenError) {
+            // Concurrent initial write
+            return await this.#getExistingDataEncryptionKeyOptions(
+              bucketName,
+              path
+            )
+          }
+          throw err2
+        }
+      }
+      throw err
+    }
+  }
+
+  async sendStream(bucketName, path, sourceStream, opts = {}) {
+    const ssecOptions =
+      opts.ssecOptions ||
+      (await this.#getDataEncryptionKeyOptions(bucketName, path))
+    return await super.sendStream(bucketName, path, sourceStream, {
+      ...opts,
+      ssecOptions,
+    })
+  }
+
+  async getObjectStream(bucketName, path, opts = {}) {
+    const ssecOptions =
+      opts.ssecOptions ||
+      (await this.#getExistingDataEncryptionKeyOptions(bucketName, path))
+    return await super.getObjectStream(bucketName, path, {
+      ...opts,
+      ssecOptions,
+    })
+  }
+
+  async getObjectSize(bucketName, path, opts = {}) {
+    const ssecOptions =
+      opts.ssecOptions ||
+      (await this.#getExistingDataEncryptionKeyOptions(bucketName, path))
+    return await super.getObjectSize(bucketName, path, { ...opts, ssecOptions })
+  }
+
+  async getObjectStorageClass(bucketName, path, opts = {}) {
+    const ssecOptions =
+      opts.ssecOptions ||
+      (await this.#getExistingDataEncryptionKeyOptions(bucketName, path))
+    return await super.getObjectStorageClass(bucketName, path, {
+      ...opts,
+      ssecOptions,
+    })
+  }
+
+  async directorySize(bucketName, path, continuationToken) {
+    // Note: Listing a bucket does not require SSE-C credentials.
+    return await super.directorySize(bucketName, path, continuationToken)
+  }
+
+  async deleteDirectory(bucketName, path, continuationToken) {
+    // Note: Listing/Deleting a prefix does not require SSE-C credentials.
+    await super.deleteDirectory(bucketName, path, continuationToken)
+    const { projectFolder, dekPath } = this.#buildProjectPaths(bucketName, path)
+    if (projectFolder === path) {
+      await super.deleteObject(
+        this.#settings.dataEncryptionKeyBucketName,
+        dekPath
+      )
+    }
+  }
+
+  async getObjectMd5Hash(bucketName, path, opts = {}) {
+    // The ETag in object metadata is not the MD5 content hash, skip the HEAD request.
+    opts = { ...opts, etagIsNotMD5: true }
+    return await super.getObjectMd5Hash(bucketName, path, opts)
+  }
+
+  async copyObject(bucketName, sourcePath, destinationPath, opts = {}) {
+    const ssecOptions =
+      opts.ssecOptions ||
+      (await this.#getDataEncryptionKeyOptions(bucketName, destinationPath))
+    const ssecSrcOptions =
+      opts.ssecSrcOptions ||
+      (await this.#getExistingDataEncryptionKeyOptions(bucketName, sourcePath))
+    return await super.copyObject(bucketName, sourcePath, destinationPath, {
+      ...opts,
+      ssecOptions,
+      ssecSrcOptions,
+    })
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @return {Promise<string>}
+   */
+  async getRedirectUrl(bucketName, path) {
+    throw new NotImplementedError('signed links are not supported with SSE-C')
+  }
+}
+
+/**
+ * Helper class for batch updates to avoid repeated fetching of the project path.
+ *
+ * A general "cache" for project keys is another alternative. For now, use a helper class.
+ */
+class CachedPerProjectEncryptedS3Persistor {
+  /** @type SSECOptions */
+  #projectKeyOptions
+  /** @type PerProjectEncryptedS3Persistor */
+  #parent
+
+  /**
+   * @param {PerProjectEncryptedS3Persistor} parent
+   * @param {SSECOptions} projectKeyOptions
+   */
+  constructor(parent, projectKeyOptions) {
+    this.#parent = parent
+    this.#projectKeyOptions = projectKeyOptions
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @param {string} fsPath
+   */
+  async sendFile(bucketName, path, fsPath) {
+    return await this.sendStream(bucketName, path, fs.createReadStream(fsPath))
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @param {NodeJS.ReadableStream} sourceStream
+   * @param {Object} opts
+   * @param {string} [opts.contentType]
+   * @param {string} [opts.contentEncoding]
+   * @param {number} [opts.contentLength]
+   * @param {'*'} [opts.ifNoneMatch]
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @param {string} [opts.sourceMd5]
+   * @return {Promise<void>}
+   */
+  async sendStream(bucketName, path, sourceStream, opts = {}) {
+    return await this.#parent.sendStream(bucketName, path, sourceStream, {
+      ...opts,
+      ssecOptions: this.#projectKeyOptions,
+    })
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} path
+   * @param {Object} opts
+   * @param {number} [opts.start]
+   * @param {number} [opts.end]
+   * @param {boolean} [opts.autoGunzip]
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @return {Promise<NodeJS.ReadableStream>}
+   */
+  async getObjectStream(bucketName, path, opts = {}) {
+    return await this.#parent.getObjectStream(bucketName, path, {
+      ...opts,
+      ssecOptions: this.#projectKeyOptions,
+    })
+  }
+}
+
+module.exports = {
+  PerProjectEncryptedS3Persistor,
+  CachedPerProjectEncryptedS3Persistor,
+  RootKeyEncryptionKey,
+}
@@ -1,15 +1,20 @@
 const Logger = require('@overleaf/logger')
 const { SettingsError } = require('./Errors')
 const GcsPersistor = require('./GcsPersistor')
-const S3Persistor = require('./S3Persistor')
+const { S3Persistor } = require('./S3Persistor')
 const FSPersistor = require('./FSPersistor')
 const MigrationPersistor = require('./MigrationPersistor')
+const {
+  PerProjectEncryptedS3Persistor,
+} = require('./PerProjectEncryptedS3Persistor')

 function getPersistor(backend, settings) {
  switch (backend) {
    case 'aws-sdk':
    case 's3':
      return new S3Persistor(settings.s3)
+    case 's3SSEC':
+      return new PerProjectEncryptedS3Persistor(settings.s3SSEC)
    case 'fs':
      return new FSPersistor({
        useSubdirectories: settings.useSubdirectories,
@@ -1,9 +1,9 @@
-const Crypto = require('crypto')
-const Stream = require('stream')
-const { pipeline } = require('stream/promises')
+const Crypto = require('node:crypto')
+const Stream = require('node:stream')
+const { pipeline } = require('node:stream/promises')
 const Logger = require('@overleaf/logger')
 const Metrics = require('@overleaf/metrics')
-const { WriteError, NotFoundError } = require('./Errors')
+const { WriteError, NotFoundError, AlreadyWrittenError } = require('./Errors')

 const _128KiB = 128 * 1024
 const TIMING_BUCKETS = [
@@ -26,12 +26,14 @@ const SIZE_BUCKETS = [
 */
 class ObserverStream extends Stream.Transform {
  /**
-   * @param {string} metric prefix for metrics
-   * @param {string} bucket name of source/target bucket
-   * @param {string} hash optional hash algorithm, e.g. 'md5'
+   * @param {Object} opts
+   * @param {string} opts.metric prefix for metrics
+   * @param {string} opts.bucket name of source/target bucket
+   * @param {string} [opts.hash] optional hash algorithm, e.g. 'md5'
   */
-  constructor({ metric, bucket, hash = '' }) {
+  constructor(opts) {
    super({ autoDestroy: true })
+    const { metric, bucket, hash = '' } = opts

    this.bytes = 0
    this.start = performance.now()
@@ -138,6 +140,10 @@ async function verifyMd5(persistor, bucket, key, sourceMd5, destMd5 = null) {
 }

 function wrapError(error, message, params, ErrorType) {
+  params = {
+    ...params,
+    cause: error,
+  }
  if (
    error instanceof NotFoundError ||
    ['NoSuchKey', 'NotFound', 404, 'AccessDenied', 'ENOENT'].includes(
@@ -146,6 +152,13 @@ function wrapError(error, message, params, ErrorType) {
    (error.response && error.response.statusCode === 404)
  ) {
    return new NotFoundError('no such file', params, error)
+  } else if (
+    params.ifNoneMatch === '*' &&
+    (error.code === 'PreconditionFailed' ||
+      error.response?.statusCode === 412 ||
+      error instanceof AlreadyWrittenError)
+  ) {
+    return new AlreadyWrittenError(message, params, error)
  } else {
    return new ErrorType(message, params, error)
  }
@@ -1,5 +1,6 @@
-const http = require('http')
-const https = require('https')
+// @ts-check
+const http = require('node:http')
+const https = require('node:https')
 if (http.globalAgent.maxSockets < 300) {
  http.globalAgent.maxSockets = 300
 }
@@ -7,27 +8,92 @@ if (https.globalAgent.maxSockets < 300) {
  https.globalAgent.maxSockets = 300
 }

+const Crypto = require('node:crypto')
 const Metrics = require('@overleaf/metrics')
 const AbstractPersistor = require('./AbstractPersistor')
 const PersistorHelper = require('./PersistorHelper')

-const { pipeline, PassThrough } = require('stream')
-const fs = require('fs')
+const { pipeline, PassThrough } = require('node:stream')
+const fs = require('node:fs')
 const S3 = require('aws-sdk/clients/s3')
-const { URL } = require('url')
+const { URL } = require('node:url')
 const { WriteError, ReadError, NotFoundError } = require('./Errors')
+const zlib = require('node:zlib')
+
+/**
+ * Wrapper with private fields to avoid revealing them on console, JSON.stringify or similar.
+ */
+class SSECOptions {
+  #keyAsBuffer
+  #keyMD5
+
+  /**
+   * @param {Buffer} keyAsBuffer
+   */
+  constructor(keyAsBuffer) {
+    this.#keyAsBuffer = keyAsBuffer
+    this.#keyMD5 = Crypto.createHash('md5').update(keyAsBuffer).digest('base64')
+  }
+
+  getPutOptions() {
+    return {
+      SSECustomerKey: this.#keyAsBuffer,
+      SSECustomerKeyMD5: this.#keyMD5,
+      SSECustomerAlgorithm: 'AES256',
+    }
+  }
+
+  getGetOptions() {
+    return {
+      SSECustomerKey: this.#keyAsBuffer,
+      SSECustomerKeyMD5: this.#keyMD5,
+      SSECustomerAlgorithm: 'AES256',
+    }
+  }
+
+  getCopyOptions() {
+    return {
+      CopySourceSSECustomerKey: this.#keyAsBuffer,
+      CopySourceSSECustomerKeyMD5: this.#keyMD5,
+      CopySourceSSECustomerAlgorithm: 'AES256',
+    }
+  }
+}
+
+class S3Persistor extends AbstractPersistor {
+  /** @type {Map<string, S3>} */
+  #clients = new Map()

-module.exports = class S3Persistor extends AbstractPersistor {
  constructor(settings = {}) {
    super()

+    settings.storageClass = settings.storageClass || {}
    this.settings = settings
  }

+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {string} fsPath
+   * @return {Promise<void>}
+   */
  async sendFile(bucketName, key, fsPath) {
-    return await this.sendStream(bucketName, key, fs.createReadStream(fsPath))
+    await this.sendStream(bucketName, key, fs.createReadStream(fsPath))
  }

+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {NodeJS.ReadableStream} readStream
+   * @param {Object} opts
+   * @param {string} [opts.contentType]
+   * @param {string} [opts.contentEncoding]
+   * @param {number} [opts.contentLength]
+   * @param {'*'} [opts.ifNoneMatch]
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @param {string} [opts.sourceMd5]
+   * @return {Promise<void>}
+   */
  async sendStream(bucketName, key, readStream, opts = {}) {
    try {
      const observeOptions = {
@@ -39,42 +105,71 @@ module.exports = class S3Persistor extends AbstractPersistor {
      // observer will catch errors, clean up and log a warning
      pipeline(readStream, observer, () => {})

-      // if we have an md5 hash, pass this to S3 to verify the upload
+      /** @type {S3.PutObjectRequest} */
      const uploadOptions = {
        Bucket: bucketName,
        Key: key,
        Body: observer,
      }

+      if (this.settings.storageClass[bucketName]) {
+        uploadOptions.StorageClass = this.settings.storageClass[bucketName]
+      }
+
      if (opts.contentType) {
        uploadOptions.ContentType = opts.contentType
      }
      if (opts.contentEncoding) {
        uploadOptions.ContentEncoding = opts.contentEncoding
      }
+      if (opts.contentLength) {
+        uploadOptions.ContentLength = opts.contentLength
+      }
+      if (opts.ifNoneMatch === '*') {
+        uploadOptions.IfNoneMatch = '*'
+      }
+      if (opts.ssecOptions) {
+        Object.assign(uploadOptions, opts.ssecOptions.getPutOptions())
+      }

      // if we have an md5 hash, pass this to S3 to verify the upload - otherwise
      // we rely on the S3 client's checksum calculation to validate the upload
-      const clientOptions = {}
+      let computeChecksums = false
      if (opts.sourceMd5) {
        uploadOptions.ContentMD5 = PersistorHelper.hexToBase64(opts.sourceMd5)
      } else {
-        clientOptions.computeChecksums = true
+        computeChecksums = true
      }

-      await this._getClientForBucket(bucketName, clientOptions)
-        .upload(uploadOptions, { partSize: this.settings.partSize })
-        .promise()
+      if (this.settings.disableMultiPartUpload) {
+        await this._getClientForBucket(bucketName, computeChecksums)
+          .putObject(uploadOptions)
+          .promise()
+      } else {
+        await this._getClientForBucket(bucketName, computeChecksums)
+          .upload(uploadOptions, { partSize: this.settings.partSize })
+          .promise()
+      }
    } catch (err) {
      throw PersistorHelper.wrapError(
        err,
        'upload to S3 failed',
-        { bucketName, key },
+        { bucketName, key, ifNoneMatch: opts.ifNoneMatch },
        WriteError
      )
    }
  }

+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {Object} [opts]
+   * @param {number} [opts.start]
+   * @param {number} [opts.end]
+   * @param {boolean} [opts.autoGunzip]
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @return {Promise<NodeJS.ReadableStream>}
+   */
  async getObjectStream(bucketName, key, opts) {
    opts = opts || {}

@@ -85,6 +180,9 @@ module.exports = class S3Persistor extends AbstractPersistor {
    if (opts.start != null && opts.end != null) {
      params.Range = `bytes=${opts.start}-${opts.end}`
    }
+    if (opts.ssecOptions) {
+      Object.assign(params, opts.ssecOptions.getGetOptions())
+    }
    const observer = new PersistorHelper.ObserverStream({
      metric: 's3.ingress', // ingress from S3 to us
      bucket: bucketName,
@@ -93,18 +191,21 @@ module.exports = class S3Persistor extends AbstractPersistor {
    const req = this._getClientForBucket(bucketName).getObject(params)
    const stream = req.createReadStream()

+    let contentEncoding
    try {
      await new Promise((resolve, reject) => {
-        req.on('httpHeaders', statusCode => {
+        req.on('httpHeaders', (statusCode, headers) => {
          switch (statusCode) {
            case 200: // full response
            case 206: // partial response
-              return resolve()
-            case 403: // AccessDenied is handled the same as NoSuchKey
+              contentEncoding = headers['content-encoding']
+              return resolve(undefined)
+            case 403: // AccessDenied
+              return // handled by stream.on('error') handler below
            case 404: // NoSuchKey
-              return reject(new NotFoundError())
+              return reject(new NotFoundError('not found'))
            default:
-              return reject(new Error('non success status: ' + statusCode))
+            // handled by stream.on('error') handler below
          }
        })
        // The AWS SDK is forwarding any errors from the request to the stream.
@@ -122,23 +223,32 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
    // Return a PassThrough stream with a minimal interface. It will buffer until the caller starts reading. It will emit errors from the source stream (Stream.pipeline passes errors along).
    const pass = new PassThrough()
-    pipeline(stream, observer, pass, err => {
+    const transformer = []
+    if (contentEncoding === 'gzip' && opts.autoGunzip) {
+      transformer.push(zlib.createGunzip())
+    }
+    pipeline(stream, observer, ...transformer, pass, err => {
      if (err) req.abort()
    })
    return pass
  }

+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @return {Promise<string>}
+   */
  async getRedirectUrl(bucketName, key) {
    const expiresSeconds = Math.round(this.settings.signedUrlExpiryInMs / 1000)
    try {
-      const url = await this._getClientForBucket(
-        bucketName
-      ).getSignedUrlPromise('getObject', {
-        Bucket: bucketName,
-        Key: key,
-        Expires: expiresSeconds,
-      })
-      return url
+      return await this._getClientForBucket(bucketName).getSignedUrlPromise(
+        'getObject',
+        {
+          Bucket: bucketName,
+          Key: key,
+          Expires: expiresSeconds,
+        }
+      )
    } catch (err) {
      throw PersistorHelper.wrapError(
        err,
@@ -149,6 +259,12 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
  }

+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {string} [continuationToken]
+   * @return {Promise<void>}
+   */
  async deleteDirectory(bucketName, key, continuationToken) {
    let response
    const options = { Bucket: bucketName, Prefix: key }
@@ -169,8 +285,8 @@ module.exports = class S3Persistor extends AbstractPersistor {
      )
    }

-    const objects = response.Contents.map(item => ({ Key: item.Key }))
-    if (objects.length) {
+    const objects = response.Contents?.map(item => ({ Key: item.Key || '' }))
+    if (objects?.length) {
      try {
        await this._getClientForBucket(bucketName)
          .deleteObjects({
@@ -200,12 +316,22 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
  }

-  async getObjectSize(bucketName, key) {
+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {Object} opts
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @return {Promise<S3.HeadObjectOutput>}
+   */
+  async #headObject(bucketName, key, opts = {}) {
+    const params = { Bucket: bucketName, Key: key }
+    if (opts.ssecOptions) {
+      Object.assign(params, opts.ssecOptions.getGetOptions())
+    }
    try {
-      const response = await this._getClientForBucket(bucketName)
-        .headObject({ Bucket: bucketName, Key: key })
+      return await this._getClientForBucket(bucketName)
+        .headObject(params)
        .promise()
-      return response.ContentLength
    } catch (err) {
      throw PersistorHelper.wrapError(
        err,
@@ -216,19 +342,51 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
  }

-  async getObjectMd5Hash(bucketName, key) {
+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {Object} opts
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @return {Promise<number>}
+   */
+  async getObjectSize(bucketName, key, opts = {}) {
+    const response = await this.#headObject(bucketName, key, opts)
+    return response.ContentLength || 0
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {Object} opts
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @return {Promise<string | undefined>}
+   */
+  async getObjectStorageClass(bucketName, key, opts = {}) {
+    const response = await this.#headObject(bucketName, key, opts)
+    return response.StorageClass
+  }
+
+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {Object} opts
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @param {boolean} [opts.etagIsNotMD5]
+   * @return {Promise<string>}
+   */
+  async getObjectMd5Hash(bucketName, key, opts = {}) {
    try {
-      const response = await this._getClientForBucket(bucketName)
-        .headObject({ Bucket: bucketName, Key: key })
-        .promise()
-      const md5 = S3Persistor._md5FromResponse(response)
-      if (md5) {
-        return md5
+      if (!opts.etagIsNotMD5) {
+        const response = await this.#headObject(bucketName, key, opts)
+        const md5 = S3Persistor._md5FromResponse(response)
+        if (md5) {
+          return md5
+        }
      }
      // etag is not in md5 format
      Metrics.inc('s3.md5Download')
      return await PersistorHelper.calculateStreamMd5(
-        await this.getObjectStream(bucketName, key)
+        await this.getObjectStream(bucketName, key, opts)
      )
    } catch (err) {
      throw PersistorHelper.wrapError(
@@ -240,6 +398,11 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
  }

+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @return {Promise<void>}
+   */
  async deleteObject(bucketName, key) {
    try {
      await this._getClientForBucket(bucketName)
@@ -256,12 +419,27 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
  }

-  async copyObject(bucketName, sourceKey, destKey) {
+  /**
+   * @param {string} bucketName
+   * @param {string} sourceKey
+   * @param {string} destKey
+   * @param {Object} opts
+   * @param {SSECOptions} [opts.ssecSrcOptions]
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @return {Promise<void>}
+   */
+  async copyObject(bucketName, sourceKey, destKey, opts = {}) {
    const params = {
      Bucket: bucketName,
      Key: destKey,
      CopySource: `${bucketName}/${sourceKey}`,
    }
+    if (opts.ssecSrcOptions) {
+      Object.assign(params, opts.ssecSrcOptions.getCopyOptions())
+    }
+    if (opts.ssecOptions) {
+      Object.assign(params, opts.ssecOptions.getPutOptions())
+    }
    try {
      await this._getClientForBucket(bucketName).copyObject(params).promise()
    } catch (err) {
@@ -274,9 +452,16 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
  }

-  async checkIfObjectExists(bucketName, key) {
+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {Object} opts
+   * @param {SSECOptions} [opts.ssecOptions]
+   * @return {Promise<boolean>}
+   */
+  async checkIfObjectExists(bucketName, key, opts) {
    try {
-      await this.getObjectSize(bucketName, key)
+      await this.getObjectSize(bucketName, key, opts)
      return true
    } catch (err) {
      if (err instanceof NotFoundError) {
@@ -291,6 +476,12 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
  }

+  /**
+   * @param {string} bucketName
+   * @param {string} key
+   * @param {string} [continuationToken]
+   * @return {Promise<number>}
+   */
  async directorySize(bucketName, key, continuationToken) {
    try {
      const options = {
@@ -304,7 +495,8 @@ module.exports = class S3Persistor extends AbstractPersistor {
        .listObjectsV2(options)
        .promise()

-      const size = response.Contents.reduce((acc, item) => item.Size + acc, 0)
+      const size =
+        response.Contents?.reduce((acc, item) => (item.Size || 0) + acc, 0) || 0
      if (response.IsTruncated) {
        return (
          size +
@@ -326,15 +518,38 @@ module.exports = class S3Persistor extends AbstractPersistor {
    }
  }

-  _getClientForBucket(bucket, clientOptions) {
-    return new S3(
-      this._buildClientOptions(
-        this.settings.bucketCreds?.[bucket],
-        clientOptions
+  /**
+   * @param {string} bucket
+   * @param {boolean} computeChecksums
+   * @return {S3}
+   * @private
+   */
+  _getClientForBucket(bucket, computeChecksums = false) {
+    /** @type {S3.Types.ClientConfiguration} */
+    const clientOptions = {}
+    const cacheKey = `${bucket}:${computeChecksums}`
+    if (computeChecksums) {
+      clientOptions.computeChecksums = true
+    }
+    let client = this.#clients.get(cacheKey)
+    if (!client) {
+      client = new S3(
+        this._buildClientOptions(
+          this.settings.bucketCreds?.[bucket],
+          clientOptions
+        )
      )
-    )
+      this.#clients.set(cacheKey, client)
+    }
+    return client
  }

+  /**
+   * @param {Object} bucketCredentials
+   * @param {S3.Types.ClientConfiguration} clientOptions
+   * @return {S3.Types.ClientConfiguration}
+   * @private
+   */
  _buildClientOptions(bucketCredentials, clientOptions) {
    const options = clientOptions || {}

@@ -356,7 +571,7 @@ module.exports = class S3Persistor extends AbstractPersistor {
    if (this.settings.endpoint) {
      const endpoint = new URL(this.settings.endpoint)
      options.endpoint = this.settings.endpoint
-      options.sslEnabled = endpoint.protocol === 'https'
+      options.sslEnabled = endpoint.protocol === 'https:'
    }

    // path-style access is only used for acceptance tests
@@ -370,9 +585,22 @@ module.exports = class S3Persistor extends AbstractPersistor {
      }
    }

+    if (options.sslEnabled && this.settings.ca && !options.httpOptions?.agent) {
+      options.httpOptions = options.httpOptions || {}
+      options.httpOptions.agent = new https.Agent({
+        rejectUnauthorized: true,
+        ca: this.settings.ca,
+      })
+    }
+
    return options
  }

+  /**
+   * @param {S3.HeadObjectOutput} response
+   * @return {string|null}
+   * @private
+   */
  static _md5FromResponse(response) {
    const md5 = (response.ETag || '').replace(/[ "]/g, '')
    if (!md5.match(/^[a-f0-9]{32}$/)) {
@@ -382,3 +610,8 @@ module.exports = class S3Persistor extends AbstractPersistor {
    return md5
  }
 }
+
+module.exports = {
+  S3Persistor,
+  SSECOptions,
+}
@@ -25,4 +25,9 @@ SandboxedModule.configure({
    },
  },
  globals: { Buffer, Math, console, process, URL },
+  sourceTransformers: {
+    removeNodePrefix: function (source) {
+      return source.replace(/require\(['"]node:/g, "require('")
+    },
+  },
 })
@@ -1,10 +1,10 @@
-const crypto = require('crypto')
+const crypto = require('node:crypto')
 const { expect } = require('chai')
 const mockFs = require('mock-fs')
-const fs = require('fs')
-const fsPromises = require('fs/promises')
-const Path = require('path')
-const StreamPromises = require('stream/promises')
+const fs = require('node:fs')
+const fsPromises = require('node:fs/promises')
+const Path = require('node:path')
+const StreamPromises = require('node:stream/promises')
 const SandboxedModule = require('sandboxed-module')
 const Errors = require('../../src/Errors')

@@ -1,4 +1,4 @@
-const { EventEmitter } = require('events')
+const { EventEmitter } = require('node:events')
 const sinon = require('sinon')
 const chai = require('chai')
 const { expect } = chai
@@ -45,11 +45,11 @@ describe('GcsPersistorTests', function () {

    files = [
      {
-        metadata: { size: 11, md5Hash: '/////wAAAAD/////AAAAAA==' },
+        metadata: { size: '11', md5Hash: '/////wAAAAD/////AAAAAA==' },
        delete: sinon.stub(),
      },
      {
-        metadata: { size: 22, md5Hash: '/////wAAAAD/////AAAAAA==' },
+        metadata: { size: '22', md5Hash: '/////wAAAAD/////AAAAAA==' },
        delete: sinon.stub(),
      },
    ]
@@ -63,7 +63,7 @@ describe('GcsPersistorTests', function () {

      read() {
        if (this.err) return this.emit('error', this.err)
-        this.emit('response', { statusCode: this.statusCode })
+        this.emit('response', { statusCode: this.statusCode, headers: {} })
      }
    }

@@ -302,7 +302,7 @@ describe('GcsPersistorTests', function () {
      })

      it('should return the object size', function () {
-        expect(size).to.equal(files[0].metadata.size)
+        expect(size).to.equal(11)
      })

      it('should pass the bucket and key to GCS', function () {
@@ -1,7 +1,7 @@
 const chai = require('chai')
 const { expect } = chai
 const SandboxedModule = require('sandboxed-module')
-const StreamPromises = require('stream/promises')
+const StreamPromises = require('node:stream/promises')

 const MODULE_PATH = '../../src/PersistorFactory.js'

@@ -32,7 +32,7 @@ describe('PersistorManager', function () {
    Settings = {}
    const requires = {
      './GcsPersistor': GcsPersistor,
-      './S3Persistor': S3Persistor,
+      './S3Persistor': { S3Persistor },
      './FSPersistor': FSPersistor,
      '@overleaf/logger': {
        info() {},
@@ -3,7 +3,7 @@ const chai = require('chai')
 const { expect } = chai
 const SandboxedModule = require('sandboxed-module')
 const Errors = require('../../src/Errors')
-const { EventEmitter } = require('events')
+const { EventEmitter } = require('node:events')

 const MODULE_PATH = '../../src/S3Persistor.js'

@@ -91,8 +91,22 @@ describe('S3PersistorTests', function () {

      createReadStream() {
        setTimeout(() => {
+          if (this.notFoundSSEC) {
+            // special case for AWS S3: 404 NoSuchKey wrapped in a 400. A single request received a single response, and multiple httpHeaders events are triggered. Don't ask.
+            this.emit('httpHeaders', 400, {})
+            this.emit('httpHeaders', 404, {})
+            ReadStream.emit('error', S3NotFoundError)
+            return
+          }
+
          if (this.err) return ReadStream.emit('error', this.err)
-          this.emit('httpHeaders', this.statusCode)
+          this.emit('httpHeaders', this.statusCode, {})
+          if (this.statusCode === 403) {
+            ReadStream.emit('error', S3AccessDeniedError)
+          }
+          if (this.statusCode === 404) {
+            ReadStream.emit('error', S3NotFoundError)
+          }
        })
        return ReadStream
      }
@@ -133,7 +147,7 @@ describe('S3PersistorTests', function () {
      deleteObjects: sinon.stub().returns(EmptyPromise),
      getSignedUrlPromise: sinon.stub().resolves(redirectUrl),
    }
-    S3 = sinon.stub().returns(S3Client)
+    S3 = sinon.stub().callsFake(() => Object.assign({}, S3Client))

    Hash = {
      end: sinon.stub(),
@@ -159,7 +173,7 @@ describe('S3PersistorTests', function () {
        crypto,
      },
      globals: { console, Buffer },
-    }))(settings)
+    }).S3Persistor)(settings)
  })

  describe('getObjectStream', function () {
@@ -338,6 +352,34 @@ describe('S3PersistorTests', function () {
      })
    })

+    describe("when the file doesn't exist -- SSEC", function () {
+      let error, stream
+
+      beforeEach(async function () {
+        S3GetObjectRequest.notFoundSSEC = 404
+        try {
+          stream = await S3Persistor.getObjectStream(bucket, key)
+        } catch (err) {
+          error = err
+        }
+      })
+      it('does not return a stream', function () {
+        expect(stream).not.to.exist
+      })
+
+      it('throws a NotFoundError', function () {
+        expect(error).to.be.an.instanceOf(Errors.NotFoundError)
+      })
+
+      it('wraps the error', function () {
+        expect(error.cause).to.exist
+      })
+
+      it('stores the bucket and key in the error', function () {
+        expect(error.info).to.include({ bucketName: bucket, key })
+      })
+    })
+
    describe('when access to the file is denied', function () {
      let error, stream

@@ -359,7 +401,7 @@ describe('S3PersistorTests', function () {
      })

      it('wraps the error', function () {
-        expect(error.cause).to.exist
+        expect(error.cause).to.equal(S3AccessDeniedError)
      })

      it('stores the bucket and key in the error', function () {
@@ -985,4 +1027,22 @@ describe('S3PersistorTests', function () {
      })
    })
  })
+
+  describe('_getClientForBucket', function () {
+    it('should return same instance for same bucket', function () {
+      const a = S3Persistor._getClientForBucket('foo')
+      const b = S3Persistor._getClientForBucket('foo')
+      expect(a).to.equal(b)
+    })
+    it('should return different instance for different bucket', function () {
+      const a = S3Persistor._getClientForBucket('foo')
+      const b = S3Persistor._getClientForBucket('bar')
+      expect(a).to.not.equal(b)
+    })
+    it('should return different instance for same bucket different computeChecksums', function () {
+      const a = S3Persistor._getClientForBucket('foo', false)
+      const b = S3Persistor._getClientForBucket('foo', true)
+      expect(a).to.not.equal(b)
+    })
+  })
 })
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ overleaf-editor-core
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -40,6 +40,11 @@ class Blob {

  static NotFoundError = NotFoundError

+  /**
+   * @param {string} hash
+   * @param {number} byteLength
+   * @param {number} [stringLength]
+   */
  constructor(hash, byteLength, stringLength) {
    this.setHash(hash)
    this.setByteLength(byteLength)
@@ -63,14 +68,14 @@ class Blob {

  /**
   * Hex hash.
-   * @return {?String}
+   * @return {String}
   */
  getHash() {
    return this.hash
  }

  setHash(hash) {
-    assert.maybe.match(hash, Blob.HEX_HASH_RX, 'bad hash')
+    assert.match(hash, Blob.HEX_HASH_RX, 'bad hash')
    this.hash = hash
  }

@@ -83,13 +88,13 @@ class Blob {
  }

  setByteLength(byteLength) {
-    assert.maybe.integer(byteLength, 'bad byteLength')
+    assert.integer(byteLength, 'bad byteLength')
    this.byteLength = byteLength
  }

  /**
   * Utf-8 length of the blob content, if it appears to be valid UTF-8.
-   * @return {?number}
+   * @return {number|undefined}
   */
  getStringLength() {
    return this.stringLength
@@ -10,7 +10,7 @@ const Change = require('./change')
 class ChangeNote {
  /**
   * @param {number} baseVersion the new base version for the change
-   * @param {?Change} change
+   * @param {Change} [change]
   */
  constructor(baseVersion, change) {
    assert.integer(baseVersion, 'bad baseVersion')
@@ -95,7 +95,7 @@ class File {

  /**
   * @param  {number} byteLength
-   * @param  {number?} stringLength
+   * @param  {number} [stringLength]
   * @param  {Object} [metadata]
   * @return {File}
   */
@@ -47,7 +47,7 @@ class FileData {

  /** @see File.createHollow
   * @param {number} byteLength
-   * @param {number|null} stringLength
+   * @param {number} [stringLength]
   */
  static createHollow(byteLength, stringLength) {
    if (stringLength == null) {
@@ -63,20 +63,14 @@ class FileData {
   */
  static createLazyFromBlobs(blob, rangesBlob) {
    assert.instance(blob, Blob, 'FileData: bad blob')
-    if (blob.getStringLength() == null) {
-      return new BinaryFileData(
-        // TODO(das7pad): see call-sites
-        // @ts-ignore
-        blob.getHash(),
-        blob.getByteLength()
-      )
+    const stringLength = blob.getStringLength()
+    if (stringLength == null) {
+      return new BinaryFileData(blob.getHash(), blob.getByteLength())
    }
    return new LazyStringFileData(
-      // TODO(das7pad): see call-sites
-      // @ts-ignore
      blob.getHash(),
      rangesBlob?.getHash(),
-      blob.getStringLength()
+      stringLength
    )
  }

@@ -142,12 +142,8 @@ class StringFileData extends FileData {
        trackedChanges: this.trackedChanges.toRaw(),
      }
      const rangesBlob = await blobStore.putObject(ranges)
-      // TODO(das7pad): Provide interface that guarantees hash exists?
-      // @ts-ignore
      return { hash: blob.getHash(), rangesHash: rangesBlob.getHash() }
    }
-    // TODO(das7pad): Provide interface that guarantees hash exists?
-    // @ts-ignore
    return { hash: blob.getHash() }
  }
 }
@@ -109,7 +109,7 @@ class History {
   * @param {BlobStore} blobStore
   * @param {number} [concurrency] applies separately to files, changes and
   *                               operations
-   * @return {Promise.<Object>}
+   * @return {Promise<import('overleaf-editor-core/lib/types').RawHistory>}
   */
  async store(blobStore, concurrency) {
    assert.maybe.number(concurrency, 'bad concurrency')
@@ -27,7 +27,7 @@ class V2DocVersions {
  }

  /**
-   * @return {?RawV2DocVersions}
+   * @return {RawV2DocVersions|null}
   */
  toRaw() {
    if (!this.data) return null
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ promise-utils
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -1,4 +1,4 @@
-const { promisify, callbackify } = require('util')
+const { promisify, callbackify } = require('node:util')
 const pLimit = require('p-limit')

 module.exports = {
@@ -253,8 +253,14 @@ function expressifyErrorHandler(fn) {
 * Map values in `array` with the async function `fn`
 *
 * Limit the number of unresolved promises to `concurrency`.
+ * @template T
+ * @template V
+ * @param {number} concurrency
+ * @param {Array<T>} array
+ * @param {(arg: T) => Promise<V>} fn
+ * @return {Promise<Array<Awaited<V>>>}
 */
-function promiseMapWithLimit(concurrency, array, fn) {
+async function promiseMapWithLimit(concurrency, array, fn) {
  const limit = pLimit(concurrency)
-  return Promise.all(array.map(x => limit(() => fn(x))))
+  return await Promise.all(array.map(x => limit(() => fn(x))))
 }
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ ranges-tracker
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -1,8 +1,8 @@
-const { promisify } = require('util')
+const { promisify } = require('node:util')
 const metrics = require('@overleaf/metrics')
 const logger = require('@overleaf/logger')
-const os = require('os')
-const crypto = require('crypto')
+const os = require('node:os')
+const crypto = require('node:crypto')

 const HOST = os.hostname()
 const PID = process.pid
@@ -1,8 +1,8 @@
-const { callbackify, promisify } = require('util')
+const { callbackify, promisify } = require('node:util')
 const metrics = require('@overleaf/metrics')
 const logger = require('@overleaf/logger')
-const os = require('os')
-const crypto = require('crypto')
+const os = require('node:os')
+const crypto = require('node:crypto')
 const async = require('async')

 const HOST = os.hostname()
@@ -5,6 +5,6 @@ redis-wrapper
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -1,6 +1,6 @@
-const crypto = require('crypto')
-const os = require('os')
-const { promisify } = require('util')
+const crypto = require('node:crypto')
+const os = require('node:os')
+const { promisify } = require('node:util')

 const Redis = require('ioredis')

@@ -0,0 +1,9 @@
+const SandboxedModule = require('sandboxed-module')
+
+SandboxedModule.configure({
+  sourceTransformers: {
+    removeNodePrefix: function (source) {
+      return source.replace(/require\(['"]node:/g, "require('")
+    },
+  },
+})
@@ -6,8 +6,8 @@
 */
 require('chai').should()
 const SandboxedModule = require('sandboxed-module')
-const assert = require('assert')
-const path = require('path')
+const assert = require('node:assert')
+const path = require('node:path')
 const sinon = require('sinon')
 const modulePath = path.join(__dirname, './../../../index.js')
 const redisLockerModulePath = path.join(__dirname, './../../../RedisLocker.js')
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -1,6 +1,6 @@
 /* eslint-disable no-console */
-const fs = require('fs')
-const Path = require('path')
+const fs = require('node:fs')
+const Path = require('node:path')
 const { merge } = require('./merge')

 const CWD = process.cwd()
@@ -5,6 +5,6 @@ settings
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -1 +1 @@
-18.20.2
+20.18.0
@@ -5,6 +5,6 @@ stream-utils
 --env-pass-through=
 --esmock-loader=False
 --is-library=True
--node-version=18.20.2
+--node-version=20.18.0
 --public-repo=False
 --script-version=4.5.0
@@ -1,8 +1,8 @@
-const { Writable, Readable, PassThrough, Transform } = require('stream')
+const { Writable, Readable, PassThrough, Transform } = require('node:stream')

 /**
 * A writable stream that stores all data written to it in a node Buffer.
- * @extends stream.Writable
+ * @extends Writable
 * @example
 * const { WritableBuffer } = require('@overleaf/stream-utils')
 * const bufferStream = new WritableBuffer()
@@ -43,7 +43,7 @@ class WritableBuffer extends Writable {

 /**
 * A readable stream created from a string.
- * @extends stream.Readable
+ * @extends Readable
 * @example
 * const { ReadableString } = require('@overleaf/stream-utils')
 * const stringStream = new ReadableString('hello world')
@@ -66,7 +66,7 @@ class SizeExceededError extends Error {}

 /**
 * Limited size stream which will emit a SizeExceededError if the size is exceeded
- * @extends stream.Transform
+ * @extends Transform
 */
 class LimitedStream extends Transform {
  constructor(maxSize) {
@@ -93,7 +93,7 @@ class AbortError extends Error {}

 /**
 * TimeoutStream which will emit an AbortError if it exceeds a user specified timeout
- * @extends stream.PassThrough
+ * @extends PassThrough
 */
 class TimeoutStream extends PassThrough {
  constructor(timeout) {
@@ -111,7 +111,7 @@ class TimeoutStream extends PassThrough {

 /**
 * LoggerStream which will call the provided logger function when the stream exceeds a user specified limit. It will call the provided function again when flushing the stream and it exceeded the user specified limit before.
- * @extends stream.Transform
+ * @extends Transform
 */
 class LoggerStream extends Transform {
  /**
@@ -5,6 +5,8 @@
    "patch-package": "^8.0.0"
  },
  "devDependencies": {
+    "@types/chai": "^4.3.0",
+    "@types/chai-as-promised": "^7.1.8",
    "@types/mocha": "^10.0.6",
    "@typescript-eslint/eslint-plugin": "^8.0.0",
    "@typescript-eslint/parser": "^8.0.0",
@@ -19,6 +21,7 @@
    "eslint-plugin-node": "^11.1.0",
    "eslint-plugin-prettier": "^4.0.0",
    "eslint-plugin-promise": "^6.0.0",
+    "eslint-plugin-unicorn": "^56.0.0",
    "prettier": "3.3.3",
    "typescript": "^5.5.4"
  },
@@ -63,7 +66,6 @@
    "services/project-history",
    "services/real-time",
    "services/references",
-    "services/spelling",
    "services/templates",
    "services/third-party-datastore",
    "services/third-party-references",
@@ -0,0 +1,23 @@
+diff --git a/node_modules/@node-saml/node-saml/lib/saml.js b/node_modules/@node-saml/node-saml/lib/saml.js
+index fba15b9..a5778cb 100644
+--- a/node_modules/@node-saml/node-saml/lib/saml.js
+++ b/node_modules/@node-saml/node-saml/lib/saml.js
+@@ -336,7 +336,8 @@ class SAML {
+         const requestOrResponse = request || response;
+         (0, utility_1.assertRequired)(requestOrResponse, "either request or response is required");
+         let buffer;
+-        if (this.options.skipRequestCompression) {
+       // logout requestOrResponse must be compressed anyway
+        if (this.options.skipRequestCompression && operation !== "logout") {
+             buffer = Buffer.from(requestOrResponse, "utf8");
+         }
+         else {
+@@ -495,7 +496,7 @@ class SAML {
+         try {
+             xml = Buffer.from(container.SAMLResponse, "base64").toString("utf8");
+             doc = await (0, xml_1.parseDomFromString)(xml);
+-            const inResponseToNodes = xml_1.xpath.selectAttributes(doc, "/*[local-name()='Response']/@InResponseTo");
+            const inResponseToNodes = xml_1.xpath.selectAttributes(doc, "/*[local-name()='Response' or local-name()='LogoutResponse']/@InResponseTo");
+             if (inResponseToNodes) {
+                 inResponseTo = inResponseToNodes.length ? inResponseToNodes[0].nodeValue : null;
+                 await this.validateInResponseTo(inResponseTo);
@@ -0,0 +1,64 @@
+diff --git a/node_modules/ldapauth-fork/lib/ldapauth.js b/node_modules/ldapauth-fork/lib/ldapauth.js
+index 85ecf36a8b..a7d07e0f78 100644
+--- a/node_modules/ldapauth-fork/lib/ldapauth.js
+++ b/node_modules/ldapauth-fork/lib/ldapauth.js
+@@ -69,6 +69,7 @@ function LdapAuth(opts) {
+   this.opts.bindProperty || (this.opts.bindProperty = 'dn');
+   this.opts.groupSearchScope || (this.opts.groupSearchScope = 'sub');
+   this.opts.groupDnProperty || (this.opts.groupDnProperty = 'dn');
+  this.opts.tlsStarted = false;
+
+   EventEmitter.call(this);
+
+@@ -108,21 +109,7 @@ function LdapAuth(opts) {
+   this._userClient.on('error', this._handleError.bind(this));
+
+   var self = this;
+-  if (this.opts.starttls) {
+-    // When starttls is enabled, this callback supplants the 'connect' callback
+-    this._adminClient.starttls(this.opts.tlsOptions, this._adminClient.controls, function(err) {
+-      if (err) {
+-        self._handleError(err);
+-      } else {
+-        self._onConnectAdmin();
+-      }
+-    });
+-    this._userClient.starttls(this.opts.tlsOptions, this._userClient.controls, function(err) {
+-      if (err) {
+-        self._handleError(err);
+-      }
+-    });
+-  } else if (opts.reconnect) {
+  if (opts.reconnect && !this.opts.starttls) {
+     this.once('_installReconnectListener', function() {
+       self.log && self.log.trace('install reconnect listener');
+       self._adminClient.on('connect', function() {
+@@ -384,6 +371,28 @@ LdapAuth.prototype._findGroups = function(user, callback) {
+  */
+ LdapAuth.prototype.authenticate = function(username, password, callback) {
+   var self = this;
+  if (this.opts.starttls && !this.opts.tlsStarted) {
+    // When starttls is enabled, this callback supplants the 'connect' callback
+    this._adminClient.starttls(this.opts.tlsOptions, this._adminClient.controls, function (err) {
+      if (err) {
+        self._handleError(err);
+      } else {
+        self._onConnectAdmin(function(){self._handleAuthenticate(username, password, callback);});
+      }
+    });
+    this._userClient.starttls(this.opts.tlsOptions, this._userClient.controls, function (err) {
+      if (err) {
+        self._handleError(err);
+      }
+    });
+  } else {
+    self._handleAuthenticate(username, password, callback);
+  }
+};
+
+LdapAuth.prototype._handleAuthenticate = function (username, password, callback) {
+  this.opts.tlsStarted = true;
+  var self = this;
+
+   if (typeof password === 'undefined' || password === null || password === '') {
+     return callback(new Error('no password given'));
@@ -4,6 +4,9 @@
    "standard",
    "prettier"
  ],
+  "plugins": [
+    "unicorn"
+  ],
  "parserOptions": {
    "ecmaVersion": 2020
  },
@@ -12,7 +15,8 @@
  },
  "rules": {
    // Do not allow importing of implicit dependencies.
-    "import/no-extraneous-dependencies": "error"
+    "import/no-extraneous-dependencies": "error",
+    "unicorn/prefer-node-protocol": "error"
  },
  "overrides": [
    // Extra rules for Cypress tests
@@ -2,7 +2,7 @@
 # Overleaf Base Image (sharelatex/sharelatex-base)
 # --------------------------------------------------

-FROM phusion/baseimage:jammy-1.0.4
+FROM phusion/baseimage:noble-1.0.0

 # Makes sure LuaTex cache is writable
 # -----------------------------------
@@ -25,13 +25,12 @@ RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
      unattended-upgrades \
      build-essential wget net-tools unzip time imagemagick optipng strace nginx git python3 python-is-python3 zlib1g-dev libpcre3-dev gettext-base libwww-perl ca-certificates curl gnupg \
      qpdf \
-      aspell aspell-en aspell-af aspell-am aspell-ar aspell-ar-large aspell-bg aspell-bn aspell-br aspell-ca aspell-cs aspell-cy aspell-da aspell-de aspell-de-1901 aspell-el aspell-eo aspell-es aspell-et aspell-eu-es aspell-fa aspell-fo aspell-fr aspell-ga aspell-gl-minimos aspell-gu aspell-he aspell-hi aspell-hr aspell-hsb aspell-hu aspell-hy aspell-id aspell-is aspell-it aspell-kk aspell-kn aspell-ku aspell-lt aspell-lv aspell-ml aspell-mr aspell-nl aspell-no aspell-nr aspell-ns  aspell-pa aspell-pl aspell-pt aspell-pt-br aspell-ro aspell-ru aspell-sk aspell-sl aspell-ss aspell-st aspell-sv aspell-tl aspell-tn aspell-ts aspell-uk aspell-uz aspell-xh aspell-zu \
 # upgrade base-image, batch all the upgrades together, rather than installing them on-by-one (which is slow!)
 &&  unattended-upgrade --verbose --no-minimal-upgrade-steps \
 # install Node.js https://github.com/nodesource/distributions#nodejs
 &&  mkdir -p /etc/apt/keyrings \
 &&  curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg \
-&&  echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_18.x nodistro main" | tee /etc/apt/sources.list.d/nodesource.list \
+&&  echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_20.x nodistro main" | tee /etc/apt/sources.list.d/nodesource.list \
 &&  apt-get update \
 &&  apt-get install -y nodejs \
    \
@@ -11,22 +11,22 @@ cd /overleaf/services/web
 case "$TASK" in
  user:create-admin)
    echo "The grunt command is deprecated, run the create-user script using node instead"
-    node modules/server-ce-scripts/scripts/create-user --admin "$@"
+    node modules/server-ce-scripts/scripts/create-user.mjs --admin "$@"
    ;;

  user:delete)
    echo "The grunt command is deprecated, run the delete-user script using node instead"
-    node modules/server-ce-scripts/scripts/delete-user "$@"
+    node modules/server-ce-scripts/scripts/delete-user.mjs "$@"
    ;;

  check:mongo)
    echo "The grunt command is deprecated, run the check-mongodb script using node instead"
-    node modules/server-ce-scripts/scripts/check-mongodb
+    node modules/server-ce-scripts/scripts/check-mongodb.mjs
    ;;

  check:redis)
    echo "The grunt command is deprecated, run the check-redis script using node instead"
-    node modules/server-ce-scripts/scripts/check-redis
+    node modules/server-ce-scripts/scripts/check-redis.mjs
    ;;

  *)
@@ -9,6 +9,6 @@ export HISTORY_V1_HOST=127.0.0.1
 export NOTIFICATIONS_HOST=127.0.0.1
 export PROJECT_HISTORY_HOST=127.0.0.1
 export REALTIME_HOST=127.0.0.1
-export SPELLING_HOST=127.0.0.1
+export REFERENCES_HOST=127.0.0.1
 export WEB_HOST=127.0.0.1
 export WEB_API_HOST=127.0.0.1
--- a/Show More
+++ b/Show More
@@ -1 +1 @@
 .20.2
 .18.0