Ruby and Rails .gitignore Configuration

Ruby projects, especially Ruby on Rails applications, generate a wide variety of files that should be excluded from version control. The .gitignore needs to cover Bundler artifacts, Rails-specific files, and runtime data.

Bundler and gem patterns:

• vendor/bundle/ — When running bundle install --deployment or bundle install --path vendor/bundle, gems are installed locally. This directory behaves like node_modules/ and should not be committed.
• *.gem — Built gem packages. If you are developing a gem, the .gem file is a distributable artifact, not source code.
• .bundle/ — Bundler configuration cache containing per-project settings.

Rails-specific patterns:

• tmp/ — Rails stores cache files, session data, PIDs, and socket files here. Everything in tmp/ is transient.
• log/ — Application log files (development.log, production.log, test.log). These grow continuously and are machine-specific.
• db/*.sqlite3 and db/*.sqlite3-* — SQLite database files used in development. Production databases should never be in the repo.
• storage/ — Active Storage uploaded files in local disk service (Rails 5.2+).
• public/assets/ — Precompiled asset pipeline output. Generated by rails assets:precompile and should be built by CI.
• public/packs/ — Webpacker output directory (Rails 5.1 to 6.x).
• node_modules/ — If using Webpacker, Importmap, or JavaScript bundling via jsbundling-rails.

Credentials handling:

Rails 5.2+ uses encrypted credentials (config/credentials.yml.enc), which IS committed. The master key (config/master.key) is what you must ignore:

config/master.key
config/credentials/*.key

The encrypted file is safe to commit because it is useless without the key. Share the master key through secure channels like a password manager, never git.

What to commit: Gemfile, Gemfile.lock (always for applications), config/credentials.yml.enc, .ruby-version, and .rubocop.yml for consistent linting.

Spring preloader: Ignore spring/*.pid to prevent Spring process ID files from being committed. Spring is a Rails application preloader that keeps a process running in the background for faster boot times.