Show stack traces in the remote repo contents cache with --verbose_failures

src/main/java/com/google/devtools/build/lib/bazel/repository/RepositoryFetchFunction.java

@@ -264,12 +264,11 @@ public SkyValue compute(SkyKey skyKey, Environment env)
                   Root.fromPath(repoRoot), excludeRepoFromVendoring);
             }
           } catch (IOException e) {
-            throw new RepositoryFunctionException(
-                new IOException(
-                    "error looking up repo %s in remote repo contents cache: %s"
-                        .formatted(repositoryName, e.getMessage()),
-                    e),
-                Transience.TRANSIENT);
+            env.getListener()
+                .handle(
+                    Event.warn(
+                        "Remote repo contents cache lookup failed for %s: %s"
+                            .formatted(repositoryName, e.getMessage())));
           }
         }
       }

src/main/java/com/google/devtools/build/lib/remote/RemoteModule.java

@@ -803,7 +803,8 @@ public void beforeCommand(CommandEnvironment env) throws AbruptExitException {
             env.getWorkspaceName(),
             remoteOptions.remoteInstanceName,
             remoteOptions.remoteAcceptCached,
-            remoteOptions.remoteUploadLocalResults));
+            remoteOptions.remoteUploadLocalResults,
+            verboseFailures));
     if (env.getDirectories().getOutputBase().getFileSystem()
         instanceof RemoteExternalOverlayFileSystem remoteFs) {
       remoteFs.beforeCommand(

src/main/java/com/google/devtools/build/lib/remote/RemoteRepoContentsCacheImpl.java

@@ -24,6 +24,7 @@
 import build.bazel.remote.execution.v2.Directory;
 import build.bazel.remote.execution.v2.Tree;
 import com.google.common.base.Splitter;
+import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.util.concurrent.Futures;
@@ -93,6 +94,7 @@ public final class RemoteRepoContentsCacheImpl implements RemoteRepoContentsCach
   private final String commandId;
   private final boolean acceptCached;
   private final boolean uploadLocalResults;
+  private final boolean verboseFailures;
   private final DigestUtil digestUtil;
   private final Action baseAction;
 
@@ -101,12 +103,14 @@ public RemoteRepoContentsCacheImpl(
       String buildRequestId,
       String commandId,
       boolean acceptCached,
-      boolean uploadLocalResults) {
+      boolean uploadLocalResults,
+      boolean verboseFailures) {
     this.buildRequestId = buildRequestId;
     this.commandId = commandId;
     this.cache = cache;
     this.acceptCached = acceptCached;
     this.uploadLocalResults = uploadLocalResults;
+    this.verboseFailures = verboseFailures;
     this.digestUtil = cache.digestUtil;
     this.baseAction =
         Action.newBuilder()
@@ -142,7 +146,7 @@ public void addToCache(
       reporter.handle(
           Event.warn(
               "Failed to read marker file repo %s, skipping: %s"
-                  .formatted(repoName, e.getMessage())));
+                  .formatted(repoName, maybeGetStackTrace(e))));
     }
     var action = buildAction(predeclaredInputHash);
     var actionKey = new ActionKey(digestUtil.compute(action));
@@ -168,7 +172,7 @@ public void addToCache(
       reporter.handle(
           Event.warn(
               "Failed to upload repo contents to remote cache for repo %s: %s"
-                  .formatted(repoName, e.getMessage())));
+                  .formatted(repoName, maybeGetStackTrace(e))));
     }
   }
 
@@ -179,6 +183,22 @@ public boolean lookupCache(
       String predeclaredInputHash,
       ExtendedEventHandler reporter)
       throws IOException, InterruptedException {
+    try {
+      return doLookupCache(repoName, repoDir, predeclaredInputHash, reporter);
+    } catch (IOException e) {
+      throw new IOException(
+          "Failed to look up repo %s in the remote repo contents cache: %s"
+              .formatted(repoName, maybeGetStackTrace(e)),
+          e);
+    }
+  }
+
+  private boolean doLookupCache(
+      RepositoryName repoName,
+      Path repoDir,
+      String predeclaredInputHash,
+      ExtendedEventHandler reporter)
+      throws IOException, InterruptedException {
     if (!(repoDir.getFileSystem() instanceof RemoteExternalOverlayFileSystem remoteFs)) {
       return false;
     }
@@ -236,7 +256,8 @@ public boolean lookupCache(
       markerFileContent = new String(markerFileContentFuture.get(), StandardCharsets.ISO_8859_1);
       repoDirectoryContent = repoDirectoryContentFuture.get();
     } catch (ExecutionException e) {
-      throw new IllegalStateException("waitForBulkTransfer should have thrown", e);
+      throw new IllegalStateException(
+          "waitForBulkTransfer should have thrown: " + maybeGetStackTrace(e));
     }
     var markerFileLines =
         Splitter.on('\n')
@@ -285,6 +306,10 @@ private Action buildAction(String predeclaredInputHash) {
         .build();
   }
 
+  private String maybeGetStackTrace(Exception e) {
+    return verboseFailures ? Throwables.getStackTraceAsString(e) : e.getMessage();
+  }
+
   private record RepoRemotePathResolver(Path fetchedRepoMarkerFile, Path fetchedRepoDir)
       implements RemotePathResolver {
 

src/main/java/com/google/devtools/build/lib/remote/RepositoryRemoteHelpersFactoryImpl.java

@@ -31,6 +31,7 @@ class RepositoryRemoteHelpersFactoryImpl implements RepositoryRemoteHelpersFacto
   private final String remoteInstanceName;
   private final boolean acceptCached;
   private final boolean uploadLocalResults;
+  private final boolean verboseFailures;
 
   RepositoryRemoteHelpersFactoryImpl(
       CombinedCache cache,
@@ -40,7 +41,8 @@ class RepositoryRemoteHelpersFactoryImpl implements RepositoryRemoteHelpersFacto
       String workspaceName,
       String remoteInstanceName,
       boolean acceptCached,
-      boolean uploadLocalResults) {
+      boolean uploadLocalResults,
+      boolean verboseFailures) {
     this.cache = cache;
     this.remoteExecutor = remoteExecutor;
     this.buildRequestId = buildRequestId;
@@ -49,6 +51,7 @@ class RepositoryRemoteHelpersFactoryImpl implements RepositoryRemoteHelpersFacto
     this.remoteInstanceName = remoteInstanceName;
     this.acceptCached = acceptCached;
     this.uploadLocalResults = uploadLocalResults;
+    this.verboseFailures = verboseFailures;
   }
 
   @Nullable
@@ -72,6 +75,6 @@ public RepositoryRemoteExecutor createExecutor() {
   @Override
   public RemoteRepoContentsCache createRepoContentsCache() {
     return new RemoteRepoContentsCacheImpl(
-        cache, buildRequestId, commandId, acceptCached, uploadLocalResults);
+        cache, buildRequestId, commandId, acceptCached, uploadLocalResults, verboseFailures);
   }
 }