What’s New in v4.0

Key New Features

Custom lockfile support

The new bundle install --lockfile option and lockfile method in Gemfile allow managing multiple lockfiles for different environments.

Go extension support

bundle gem --ext=go generates gems with Go native extensions, expanding beyond Ruby and Rust.

JSON output for bundle list

bundle list --format=json provides machine-readable dependency output.

Performance Improvements

• Parallel git operations for faster resolution of git-sourced gems.
• Fewer network roundtrips via adjusted API_REQUEST_LIMIT.

Major Breaking Changes

New enabled defaults

• cache_all - Caches all gems including git gems by default.
• lockfile_checksums - Checksums are now included in the lockfile by default.

Removed commands and flags

• bundle viz and bundle inject commands removed.
• bundle install --binstubs now raises an error.
• bundle show --outdated now raises an error.
• bundle remove --install now raises an error.
• --rubocop flag to bundle gem removed.
• --local-git flag to bundle plugin install removed.
• All “remembered CLI flags” removed.

Removed features

• Multiple global sources in Gemfile/lockfile no longer supported.
• allow_offline_install setting removed.
• deployment, capistrano, vlad entrypoints removed.
• Various deprecated Bundler.* helper methods removed.

Lockfile changes

• Triple spacing fix for cleaner lockfile formatting.
• Patchlevel hidden from lockfile.

Security

• Vendored URI bumped to 1.0.4.

Notable Enhancements

• Better “did you mean” gem suggestions using DidYouMean::SpellChecker.
• Improved Windows loading support.
• Better error messages for gemspec/path source conflicts.
• Checksums now work for gems on private servers.

Full 4.0 changelog