overleaf-cep/services/clsi

overleaf/clsi

A web api for compiling LaTeX documents in the cloud

The Common LaTeX Service Interface (CLSI) provides a RESTful interface to traditional LaTeX tools (or, more generally, any command line tool for composing marked-up documents into a display format such as PDF or HTML). The CLSI listens on the following ports by default:

• TCP/3013 - the RESTful interface
• TCP/3048 - reports load information
• TCP/3049 - HTTP interface to control the CLSI service

These defaults can be modified in config/settings.defaults.js.

The provided Dockerfile builds a Docker image which has the Docker command line tools installed. The configuration in docker-compose-config.yml mounts the Docker socket, in order that the CLSI container can talk to the Docker host it is running in. This allows it to spin up sibling containers running an image with a TeX distribution installed to perform the actual compiles.

The CLSI can be configured through the following environment variables:

• ALLOWED_COMPILE_GROUPS - Space separated list of allowed compile groups
• ALLOWED_IMAGES - Space separated list of allowed Docker TeX Live images
• CATCH_ERRORS - Set to true to log uncaught exceptions
• COMPILE_GROUP_DOCKER_CONFIGS - JSON string of Docker configs for compile groups
• SANDBOXED_COMPILES - Set to true to use sibling containers
• SANDBOXED_COMPILES_HOST_DIR_COMPILES - Working directory for LaTeX compiles
• SANDBOXED_COMPILES_HOST_DIR_OUTPUT - Output directory for LaTeX compiles
• COMPILE_SIZE_LIMIT - Sets the body-parser limit
• DOCKER_RUNTIME -
• FILESTORE_DOMAIN_OVERRIDE - The url for the filestore service e.g.http://$FILESTORE_HOST:3009
• FILESTORE_PARALLEL_FILE_DOWNLOADS - Number of parallel file downloads
• LISTEN_ADDRESS - The address for the RESTful service to listen on. Set to 0.0.0.0 to listen on all network interfaces
• PROCESS_LIFE_SPAN_LIMIT_MS - Process life span limit in milliseconds
• SMOKE_TEST - Whether to run smoke tests
• TEXLIVE_IMAGE - The TeX Live Docker image to use for sibling containers, e.g. us-east1-docker.pkg.dev/overleaf-ops/ol-docker/texlive-full:2026.1
• TEX_LIVE_IMAGE_NAME_OVERRIDE - The name of the registry for the Docker image e.g. us-east1-docker.pkg.dev/overleaf-ops/ol-docker
• TEXLIVE_IMAGE_USER - When using sibling containers, the user to run as in the TeX Live image. Defaults to tex
• TEXLIVE_OPENOUT_ANY - Sets the openout_any environment variable for TeX Live (see the \openout primitive documentation)

Further environment variables configure the metrics module

Installation

The CLSI can be installed and set up as part of the entire Overleaf stack (complete with front end editor and document storage), or it can be run as a standalone service. To run is as a standalone service, first checkout this repository:

git clone git@github.com:overleaf/overleaf.git

Then build the Docker image:

docker build . -t overleaf/clsi -f services/clsi/Dockerfile

Then pull the TeX Live image:

docker pull texlive/texlive

Then start the Docker container:

docker run --rm \
  -p 127.0.0.1:3013:3013 \
  -e LISTEN_ADDRESS=0.0.0.0 \
  -e SANDBOXED_COMPILES=true \
  -e TEXLIVE_IMAGE=texlive/texlive \
  -e TEXLIVE_IMAGE_USER=root \
  -e SANDBOXED_COMPILES_HOST_DIR_COMPILES="$PWD/compiles" \
  -v "$PWD/compiles:/overleaf/services/clsi/compiles" \
  -v "$PWD/cache:/overleaf/services/clsi/cache" \
  -v /var/run/docker.sock:/var/run/docker.sock \
  --name clsi \
  overleaf/clsi

Note: if you're running the CLSI in macOS you may need to use -v /var/run/docker.sock.raw:/var/run/docker.sock instead.

The CLSI should then be running at http://localhost:3013

Important note for Linux users

The Node application runs as user node in the CLSI, which has uid 1000. As a consequence of this, the compiles folder gets created on your host with uid and gid set to 1000.

ls -lnd compiles

drwxr-xr-x 2 1000 1000 4096 Mar 19 12:41 compiles

If there is a user/group on your host which also happens to have uid / gid 1000 then that user/group will have ownership of the compiles folder on your host.

LaTeX runs in the sibling containers as the user specified in the TEXLIVE_IMAGE_USER environment variable. In the example above this is set to root, which has uid 0. This creates a problem with the above permissions, as the root user does not have permission to write to subfolders of compiles.

A quick fix is to give the root group ownership and read write permissions to compiles, with setgid set so that new subfolders also inherit this ownership:

sudo chown -R 1000:root compiles
sudo chmod -R g+w compiles
sudo chmod g+s compiles

Another solution is to create a overleaf group and add both root and the user with uid 1000 to it. If the host does not have a user with that uid, you will need to create one first.

sudo useradd --uid 1000 host-node-user # If required
sudo groupadd overleaf
sudo usermod -a -G overleaf root
sudo usermod -a -G overleaf $(id -nu 1000)
sudo chown -R 1000:overleaf compiles
sudo chmod -R g+w compiles
sudo chmod g+s compiles

This is a facet of the way docker works on Linux. See this upstream issue

API

The CLSI is based on a JSON API.

Example Request

(Note that valid JSON should not contain any comments like the example below).

POST /project/<project-id>/compile

{
  compile: {
    options: {
      // Which compiler to use. Can be latex, pdflatex, xelatex or lualatex
      compiler: 'lualatex',
      // How many seconds to wait before killing the process. Default is 60.
      timeout: 40,
    },
    // The main file to run LaTeX on
    rootResourcePath: 'main.tex',
    // An array of files to include in the compilation. May have either the content
    // passed directly, or a URL where it can be downloaded.
    resources: [
      {
        path: 'main.tex',
        content: '\\documentclass{article}\n\\begin{document}\nHello World\n\\end{document}',
      },
      // ,{
      //     "path": "image.png",
      //     "url": "www.example.com/image.png",
      //     "modified": 123456789 // Unix time since epoch
      // }
    ],
  },
}

With curl, if you place the above JSON in a file called data.json, the request would look like this:

curl -X POST -H 'Content-Type: application/json' -d @data.json http://localhost:3013/project/<id>/compile

You can specify any project-id in the URL, and the files and LaTeX environment will be persisted between requests. URLs will be downloaded and cached until provided with a more recent modified date.

Example Response

{
  "compile": {
    "status": "success",
    "outputFiles": [
      {
        "type": "pdf",
        "url": "http://localhost:3013/project/<project-id>/output/output.pdf"
      },
      {
        "type": "log",
        "url": "http://localhost:3013/project/<project-id>/output/output.log"
      }
    ]
  }
}

License

The code in this repository is released under the GNU AFFERO GENERAL PUBLIC LICENSE, version 3. A copy can be found in the LICENSE file.

Copyright (c) Overleaf, 2014-2021.