feat: support installing gems from Git by withered-magic · Pull Request #312 · bazel-contrib/rules_ruby

withered-magic · 2026-01-27T11:58:03Z

Fixes: #62

Adds support for installing gems from Git by including the Git sources in vendor/cache. Currently this uses git directly, but I'm planning to follow this PR up with another PR to use @sushain97's approach of downloading source archives from GitHub with the Bazel downloader.

Right now doesn't support Windows as I wasn't able to get this working with my limited Windows knowledge :(

AI Disclaimer

Core logic was written by me, only used AI for comments, setting up the example scaffolding as well as some of the more tedious parsing tests.

sushain97 · 2026-01-27T15:47:59Z

ruby/private/bundle_install/sync_bundle_cache.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+require 'fileutils'


Would it be reasonable to add a high-level comment on what this file does?

I think it's basically rsync'ing gemspec/extconf.rb files?

just added a comment but yep exactly! we need this rsync-style functionality when there are Git gems because I noticed that there's some logic in Bunder / some gems that tries to normalize these files, which runs into "file is read-only" errors since it eventually tries to rewrite the (read-only bc of sandboxing) files from vendor/cache, so I need to make a copy of vendor/cache so that Bundler can rewrite stuff as it wants.

So to get around this I needed to make another copy which preserves symlinks except for those files that can potentially get rewritten by bundler (so far I've only noticed this happen for gemspecs and extconf.rb)

sushain97 · 2026-01-27T15:48:43Z

ruby/tests/gemfile_lock_parser_tests.bzl

+   2.3.0
+"""
+
+# Sample Gemfile.lock content with multiple Git gems from same repo


Not sure these comments add much, I might just drop them?

(similar observation for a lot of the comments below, my guess is they're AI remnants)

yep, I'll remove these!

sushain97 · 2026-01-27T15:51:18Z

ruby/private/bundle_install/sync_bundle_cache.rb

+
+raise 'must provide both srcdir and destdir' unless ARGV.length >= 2
+
+$srcdir, $destdir = *ARGV


Is there a particular reason to use globals here vs something a bit more idiomatic, i.e. logic nested under if $PROGRAM_NAME == __FILE__

just refactored it to make it a bit more idiomatic and remove the globals!

sushain97 · 2026-01-27T16:09:21Z

ruby/private/bundle_fetch.bzl

+    _git_reset(rctx, git_repo)
+    _git_clean(rctx, git_repo)
+
+    git_metadata_folder = git_repo.directory.get_child(".git")


Why do we delete this? Worth a comment

I'll add a comment! Was mostly since this shouldn't be used by Bundler down the line and therefore didn't want it end up as an unnecessary input to the bundle install action later

sushain97 · 2026-01-28T07:25:36Z

ruby/private/bundle_fetch.bzl

+    if remote_name.endswith(".git"):
+        remote_name = remote_name[:-4]
+
+    extracted_path = "%s/%s-%s" % (cache_path, remote_name, git_package.revision[:12])


I assume the 12 here is arbitrary?

ah this is to match up with the exact naming format that Bundler creates the directory with in vendor/cache for gems installed from Git

oh, fun! probably worth a comment then, given this is load-bearing

p0deje · 2026-01-29T21:22:33Z

Right now doesn't support Windows as I wasn't able to get this working with my limited Windows knowledge :(

What issues were you seeing? I wonder if those are related to git, and switching to the Bazel downloader would help?

withered-magic · 2026-01-29T21:35:27Z

Ah, it wasn't related to git - it was more that sync_bundle_cache.rb didn't seem to be working, i.e. for some reason Bundler wasn't able to install the gems from the synced vendor/cache any more. So not sure that switching to the Bazel downloader would be enough to fix, I can continue investigation though if want to fix that before landing this PR!

p0deje · 2026-02-02T23:18:48Z

Ah, it wasn't related to git - it was more that sync_bundle_cache.rb didn't seem to be working, i.e. for some reason Bundler wasn't able to install the gems from the synced vendor/cache any more. So not sure that switching to the Bazel downloader would be enough to fix, I can continue investigation though if want to fix that before landing this PR!

It would be nice to have Windows - we generally tend to keep implementation consistent across all operating systems. I'm happy to help you debug this on Slack!

withered-magic · 2026-02-02T23:30:11Z

sounds good! I'll keep investigating this tonight and reach out on slack if needed!

withered-magic · 2026-02-03T11:17:03Z

works on windows now! i also added another test to make sure creating executable targets for git gems also works

p0deje

Great work, I'm happy to merge once CI is green. Though I think there is a space to simplify it, feel free to ignore my comments if you disagree.

p0deje · 2026-02-17T16:55:21Z

docs/rules.md


+<a id="rb_git_gem"></a>
+
+## rb_git_gem


Can you add docs for this rule similar to rb_gem?

Exposes a Ruby gem cloned from Git.

You normally don't need to call this rule directly as it's an internal one used by rb_bundle_fetch().

p0deje · 2026-02-17T16:56:32Z

examples/deep_gem/hello_world/bin/hello_world

Are changes in examples/deep_gem necessary?

p0deje · 2026-02-17T16:58:47Z

examples/git_gem/spec/BUILD

+    srcs = ["hello_world_bin_spec.rb"],
+    args = ["spec/hello_world_bin_spec.rb"],
+    data = ["@bundle//bin:hello_world"],
+    env = {"HELLO_WORLD_BIN": "$(rlocationpath @bundle//bin:hello_world)"},


Are you specifically testing the environment variable expansion?

p0deje · 2026-02-17T17:01:11Z

examples/git_gem/.bazelrc

FWIW, it might be easier to move the Git gem and related files to examples/gem - it would be easier to maintain since there is a lot of duplication for Bazel setup and CI configs.

Feel free to ignore this one!

p0deje · 2026-02-17T18:00:50Z

ruby/private/bundle_fetch/BUILD.tpl

 """@generated by @rules_ruby//:ruby/private/bundle_fetch.bzl"""

-load("@rules_ruby//ruby:defs.bzl", "rb_bundle_install", "rb_gem", "rb_gem_install")
+load("@rules_ruby//ruby:defs.bzl", "rb_bundle_install", "rb_gem", "rb_gem_install", "rb_git_gem")


The function is not used, I think you can safely remove import.

p0deje · 2026-02-17T18:04:48Z

ruby/private/bundle_fetch.bzl

+    dirs_to_visit = [rctx.path(directory)]
+    gemspec_dirs = []
+
+    for i in range(10000):  # Bounded loop required by Starlark


TIL how to write while in Starlark

p0deje · 2026-02-17T18:06:36Z

ruby/private/gem.bzl

    """,
 )
+
+def _rb_git_gem_impl(ctx):


What do you think about adding the srcs attribute to rb_gem? This way, you won't need to add a new rule.

withered-magic added 6 commits January 27, 2026 03:02

.

52423bb

add tests + example

4e852eb

add changes for Windows

cbb93d6

add examples/git_gem job

9c39391

add .bazelversion symlink to examples/git_gem

63edaaf

ci

4bc8760

sushain97 reviewed Jan 27, 2026

View reviewed changes

pr feedback

47f1d62

sushain97 approved these changes Jan 28, 2026

View reviewed changes

withered-magic added 2 commits February 2, 2026 20:47

windows support

ff43dca

add hello_world binary

f6762ba

withered-magic force-pushed the withered-magic/git-gems branch from 016db8d to f6762ba Compare February 3, 2026 09:11

add test case for installed executable

6258b77

withered-magic force-pushed the withered-magic/git-gems branch from 9b1a2a0 to 6258b77 Compare February 3, 2026 10:00

reorganize tests

ac61d69

p0deje reviewed Feb 17, 2026

View reviewed changes

		@@ -0,0 +1,29 @@
		# frozen_string_literal: true
		require 'fileutils'


		raise 'must provide both srcdir and destdir' unless ARGV.length >= 2

		$srcdir, $destdir = *ARGV

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p0deje commented Jan 29, 2026

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withered-magic commented Jan 27, 2026 •

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withered-magic commented Jan 29, 2026 •

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