bazelbuild/bazel

`repository_ctx.watch_tree` attempts to watch invalid files in `.git` directories.

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#25,764 opened on Apr 3, 2025

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P2help wantedteam-ExternalDepstype: feature request

Description

Description of the bug:

When using repository_ctx.watch_tree on a directory that contains a .git directory which has enabled core.fsmonitor, the .git directory may contain a .git/fsmonitor--daemon.ipc which is un-watchable and thus it fails with the following message:

File "/private/var/tmp/_bazel_lpadron/9ae9416857eb79bb978de35a53d54970/external/rules_swift_package_manager+/swiftpkg/internal/local_swift_package.bzl", line 20, column 34, in _list_contents
                repository_ctx.watch_tree(path)
Error in watch_tree: java.io.FileNotFoundException: /Users/lpadron/Development/swift-command-line-tools/.git/fsmonitor--daemon.ipc (Operation not supported on socket)

Should we be watching .git directories at all?

Proposed solution:

  • Respect .bazelignore from the root module when using watch_tree
  • Respect ignored_directory from the root module when using watch_tree
  • Either always ignore .git directories in watch_tree or add API to watch_tree to allow rule authors to set ignored directories.

Which category does this issue belong to?

External Dependency

What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Attempt to watch_tree a git repository that has the fsmonitor daemon.

Which operating system are you running Bazel on?

macOS 15.4

What is the output of bazel info release?

8.1.1

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

No response

What's the output of git remote get-url origin; git rev-parse HEAD ?

If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

No response

Have you found anything relevant by searching the web?

No response

Any other information, logs, or outputs that you want to share?

No response

Contributor guide

Tech stack
java
Domain
backenddeveloper experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic understanding of BazelJavaFile watching mechanismsGit internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Investigate the watch tree implementation in Bazel's source code, specifically the Java class responsible for file watching (likely in src/main/java/com/google/devtools/build/lib/...). Understand how it currently handles .git directories. Consider implementing one of the proposed solutions: respecting .bazelignore, respecting ignored directory, or adding an API to watch tree for ignored directories. Test on a repository with git fsmonitor enabled. Discuss in the issue comments with maintainers.