From 75057c90704259e33ea413e5efc2a41cef75170c Mon Sep 17 00:00:00 2001
From: Yasuo Honda <yasuo.honda@gmail.com>
Date: Mon, 26 Jan 2026 21:04:04 +0900
Subject: [PATCH] Update fallback RubyGems version to 3.4.22

Since the oldest stable branch in Rails CI is now 7-0-stable,
update the fallback RubyGems version to 3.4.22, which is the latest version available
for Ruby 2.7.0 (the required_ruby_version for Rails 7.0).

- RubyGems 4.0 does not support Ruby 2.7
```
$ ruby -v
ruby 2.7.8p225 (2023-03-30 revision 1f4d455848) [x86_64-linux]
$ gem -v
3.1.6
$ bundler -v
Bundler version 2.1.4
$ gem update --system
Updating rubygems-update
Fetching rubygems-update-4.0.4.gem
ERROR:  Error installing rubygems-update:
	There are no versions of rubygems-update (= 4.0.4) compatible with your Ruby & RubyGems
	rubygems-update requires Ruby version >= 3.2.0. The current ruby version is 2.7.8.225.
ERROR:  While executing gem ... (NoMethodError)
    undefined method `version' for nil:NilClass
```

- RubyGems 3.4.22 is the last/latest version that supports Ruby 2.7

```
$ gem update --system 3.4.22
Updating rubygems-update
Fetching rubygems-update-3.4.22.gem
Successfully installed rubygems-update-3.4.22
Parsing documentation for rubygems-update-3.4.22
Installing ri documentation for rubygems-update-3.4.22
Installing darkfish documentation for rubygems-update-3.4.22
Done installing documentation for rubygems-update after 1 seconds
Parsing documentation for rubygems-update-3.4.22
Done installing documentation for rubygems-update after 0 seconds
Installing RubyGems 3.4.22
  Successfully built RubyGem
  Name: bundler
  Version: 2.4.22
  File: bundler-2.4.22.gem
Bundler 2.4.22 installed
RubyGems 3.4.22 installed
Regenerating binstubs
Regenerating plugins
Parsing documentation for rubygems-3.4.22
Installing ri documentation for rubygems-3.4.22

... snip ...

RubyGems system software updated
$ ruby -v
ruby 2.7.8p225 (2023-03-30 revision 1f4d455848) [x86_64-linux]
$ gem -v
3.4.22
$ bundler -v
Bundler version 2.4.22
$
```

- RubyGems v3.5.0
https://github.com/ruby/rubygems/releases/tag/v3.5.0
> Drop ruby 2.6 and 2.7 support.

- Drop ruby 2.6 and 2.7 support
https://github.com/ruby/rubygems/pull/7116
---
 Dockerfile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Dockerfile b/Dockerfile
index 9cceeab..df16d54 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -7,7 +7,7 @@ ENV CACHE_INVALIDATION=1
 ARG BUNDLER
 ARG RUBYGEMS
 RUN set -ex && echo "--- :ruby: Updating RubyGems and Bundler" \
-    && (gem update --system ${RUBYGEMS:-} || gem update --system 3.3.27) \
+    && (gem update --system ${RUBYGEMS:-} || gem update --system 3.4.22) \
     && ruby --version && gem --version && bundle --version \
     && codename="$(. /etc/os-release; x="${VERSION_CODENAME-${VERSION#*(}}"; echo "${x%%[ )]*}")" \
     && echo "--- :package: Installing system deps for debian '$codename'" \