Subbundle allows you to boot and require specific gems from your main gem bundle. This can help if you have a very large number of gems in your Gemfile.lock and it takes 1+ seconds to boot your bundle. This is especially useful for binstubs where you can simply load the gem that binstub needs.

Add to your application's Gemfile:

gem 'subbundle'

Add the subbundle binstub to your project:

PROJECT_DIR/bin/subbundle

# This file loads Subbundle without using loading other gems in the Gemfile, in order to be fast.
# It gets overwritten when you run the `subbundle binstub` command.

unless defined?(Subbundle)
  require "bundler"

  Bundler.locked_gems.specs.find { |spec| spec.name == "subbundle" }&.tap do |subbundle|
    Gem.use_paths Gem.dir, Bundler.bundle_path.to_s, *Gem.path
    gem "subbundle", subbundle.version
    require "subbundle"
  end
end

To use subbundle in your binstub, simply modify your existing binstub:

# Load the subbundle binstub first.
load File.expand_path("subbundle", __dir__)
# Setup the subbundle.
Subbundle.setup("rubocop")

# Execute the binary.
load Gem.bin_path("rubocop", "rubocop")

You're not limited to just one gem. You can load as many gems in your subbundle as you need:

# Load the subbundle binstub first.
load File.expand_path("subbundle", __dir__)
# Setup the subbundle.
Subbundle.setup(*%w(
  rubocop
  rubocop-performance
)

# Execute the binary.
load Gem.bin_path("rubocop", "rubocop")

In a project with ~600 gems...

Before

$ time bin/rubocop --version
$ bin/rubocop --version  2.62s user 0.37s system 97% cpu 3.063 total

After

$ time bin/rubocop --version
bin/rubocop --version  0.51s user 0.16s system 92% cpu 0.720 total

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/rubyatscale/subbundle. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the Subbundle project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.