Gemlist

I built gemlist because I wanted a programmatic way to do what dundler does:

1. Figure out what gems would be installed by a given project

2. Give each one a separate RUN gem install $name -v $version line in a Dockerfile

I want this capability because a containerization tool I work on builds Docker images from template-generated Dockerfiles, and it’d be nice to not have to wait for nokogiri to re-install every time we need to re-containerize a Rails application (as an example).

Given this, I have a very specific set of assumptions:

• I don’t care about local (:path => ...) dependencies.

• I don’t care about git (:git => ...) dependencies.

• I do care about being able to include or exclude bundle groups.

• I don’t actually want to install gems, just get a list of them.

• I have local filesystem access to the Gemfile and Gemfile.lock of the target project.

If these assumptions line up with a problem you’re trying to solve, then I hope this saves you time and energy! And, if it does, feel free to contact me, because I’d be interested in hearing about the super-cool thing you’re doing with this.

Use

require 'gemlist'

gemlist = Gemlist.new("/path/to/project")

gemlist.gems.each do |gem|
  puts "RUN gem install #{gem.name} -v #{gem.version}"
end

If you want to exclude gem groups, you can do that:

gemlist = Gemlist.new("/path/to/project", without: [:development, :test])

If you want to include addition gem groups, you can do that too:

gemlist = Gemlist.new("/path/to/project", with: [:assets])

Installation

Add this line to your application’s Gemfile:

gem 'gemlist'

And then execute:

$ bundle

Or install it yourself as:

$ gem install gemlist

Development

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 tags, and push the .gem file to rubygems.org.

Contributing

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

License

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