[git-bridge] Make liveness detect a dead service

GitOrigin-RevId: 266f6db044eec8b362b07bdfed45f892dd272413

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/Bridge.java

@@ -3,6 +3,9 @@ package uk.ac.ic.wlgitbridge.bridge;
 import com.google.api.client.auth.oauth2.Credential;
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.sql.Timestamp;
 import java.time.LocalDateTime;
 import java.util.*;
@@ -244,9 +247,28 @@ public class Bridge {
   public boolean healthCheck() {
     try {
       dbStore.getNumProjects();
-      File rootDirectory = new File("/");
-      if (!rootDirectory.exists()) {
-        throw new Exception("bad filesystem state, root directory does not exist");
+      // Check the repo store volume (the PVC mounted at the repo store root), not the
+      // container root filesystem. A read-only or detached volume must fail the check.
+      File rootDirectory = repoStore.getRootDirectory();
+      if (rootDirectory == null || !rootDirectory.isDirectory()) {
+        throw new Exception("repo store root directory does not exist: " + rootDirectory);
+      }
+      // Write and read back a small probe file to confirm the volume is mounted read-write.
+      // Use the .wlgb directory (excluded from project purging) so we never touch project
+      // storage. A single fixed-name file is overwritten on each probe (never deleted), so we
+      // avoid churning through unique files and can't leave orphaned temp files behind. Both
+      // liveness and readiness probes write identical content, so this is safe under concurrent
+      // probes.
+      File wlgbDirectory = new File(rootDirectory, ".wlgb");
+      if (!wlgbDirectory.isDirectory()) {
+        throw new Exception("repo store .wlgb directory does not exist: " + wlgbDirectory);
+      }
+      Path probeFile = new File(wlgbDirectory, ".health_check").toPath();
+      byte[] payload = "ok".getBytes(StandardCharsets.UTF_8);
+      Files.write(probeFile, payload);
+      byte[] readBack = Files.readAllBytes(probeFile);
+      if (!Arrays.equals(payload, readBack)) {
+        throw new Exception("repo store health check file content mismatch: " + probeFile);
       }
       Log.debug("[HealthCheck] passed");
       return true;

services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/BridgeTest.java

@@ -1,12 +1,17 @@
 package uk.ac.ic.wlgitbridge.bridge;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.*;
 
+import java.io.File;
 import java.io.IOException;
 import java.util.ArrayDeque;
 import java.util.Optional;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 import uk.ac.ic.wlgitbridge.application.config.Config;
 import uk.ac.ic.wlgitbridge.bridge.db.DBStore;
 import uk.ac.ic.wlgitbridge.bridge.db.ProjectState;
@@ -27,6 +32,8 @@ import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocResult;
  */
 public class BridgeTest {
 
+  @Rule public TemporaryFolder tempFolder = new TemporaryFolder();
+
   private Bridge bridge;
 
   private ProjectLock lock;
@@ -71,6 +78,28 @@ public class BridgeTest {
     verify(gcJob).stop();
   }
 
+  @Test
+  public void healthCheckPassesWhenRepoStoreRootIsWritable() throws IOException {
+    File rootDirectory = tempFolder.newFolder("repostore");
+    new File(rootDirectory, ".wlgb").mkdir();
+    when(repoStore.getRootDirectory()).thenReturn(rootDirectory);
+    assertTrue(bridge.healthCheck());
+  }
+
+  @Test
+  public void healthCheckFailsWhenRepoStoreRootIsMissing() {
+    File rootDirectory = new File(tempFolder.getRoot(), "does-not-exist");
+    when(repoStore.getRootDirectory()).thenReturn(rootDirectory);
+    assertFalse(bridge.healthCheck());
+  }
+
+  @Test
+  public void healthCheckFailsWhenWlgbDirectoryIsMissing() throws IOException {
+    File rootDirectory = tempFolder.newFolder("repostore");
+    when(repoStore.getRootDirectory()).thenReturn(rootDirectory);
+    assertFalse(bridge.healthCheck());
+  }
+
   @Test
   public void updatingRepositorySetsLastAccessedTime()
       throws IOException, GitUserException, CannotAcquireLockException {

services/git-bridge/start.sh

@@ -5,7 +5,7 @@
 VERSION=$(date +%y%m%d%H%M%S)
 
 if [ -z "$GIT_BRIDGE_JVM_ARGS" ]; then
-  GIT_BRIDGE_JVM_ARGS="-XX:+UseContainerSupport -XX:MaxRAMPercentage=50.0"
+  GIT_BRIDGE_JVM_ARGS="-XX:+UseContainerSupport -XX:MaxRAMPercentage=50.0 -XX:+ExitOnOutOfMemoryError"
 fi
 
 if [ "$ENABLE_PROFILE_AGENT" = "true" ]; then