What Is Gemfile?
Gemfile explained, including what it does and how it matters in CI/CD.
A Gemfile declares the gem dependencies of a Ruby project, read by Bundler.
What it is
It lists gems and version constraints. Bundler resolves them and writes the exact versions to Gemfile.lock.
Why it matters in CI/CD
CI runs bundle install and, for reproducibility, bundle install --frozen or sets BUNDLE_FROZEN, which fails if the Gemfile and lock are out of sync.
Key takeaways
- Gemfile declares Ruby gems.
- Bundler resolves it to Gemfile.lock.
- Use frozen mode in CI.