BUNDLE_ONLY is now available

I recently added BUNDLE_ONLY option to Bundler.

This is the long-awaited feature from 8+ years ago that allows you to install only the gem groups you need, available from bundler 2.3.19.

• https://github.com/rubygems/bundler-features/issues/59
• https://github.com/rubygems/bundler/pull/4907
• https://github.com/rubygems/rubygems/issues/4048
• https://github.com/rubygems/rubygems/pull/5759

For example, in our Rails app, we have a crazy number of gem groups (terrible I know). There is a workflow to run RuboCop with GitHub Actions, but this workflow only requires the gems in the rubocop gem group to be installed.

# .github/workflows/rubocop.yml
 env:
-  BUNDLE_WITHOUT: >
-    danger
-    default
-    development
-    feature1
-    feature2
-    feature3
-    feature4
-    feature5
-    feature6
-    feature7
-    mobile
-    production
-    qa
-    staging1
-    staging2
-    staging3
-    test
+  BUNDLE_ONLY: rubocop

Previously, it was necessary to use BUNDLE_WITHOUT to exclude unwanted gem groups one by one, but now BUNDLE_ONLY allows us to write this way 😃