What is the Correct Way To Add a :staging group to My Gemfile

Question

I have remotes set up on Heroku for production and staging.

On staging I have set the app's envs to include:

RACK_ENV=staging
RAILS_ENV=staging

I would like to be able to specify a staging group in my Gemfile in the same way I can currently use production, test or assets:

group :staging do
  gem "example", "~> 0.9"
end

I understand how to add custom groups. From my application.rb:

  groups = {
    assets: %w(development test)
  }
  Bundler.require(:security, :model, :view, *Rails.groups(groups))

But how do I add a group that is only loaded in staging?

I've tried without success:

  groups = {
    assets: %w(development test),
    staging: %(staging)
  }
  Bundler.require(:security, :model, :view, *Rails.groups(groups))

Answer 1

Your Gemfile could include a group as follows:

# Gemfile
  group :staging do
    gem 'example','~>1.0'
  end

Create an environment for staging

# /config/environments/staging.rb
... 
copy config/environments/production.rb code here with adjustments as needed
...

The reason this works is found in /config/application.rb.

Rails.groups includes the :default group (all ungrouped gems) and the gem group matching the name of the environment, set by RAILS_ENV, which in this case would be "staging". Your require. Your Bundler.require should look like:

Bundler.require *Rails.groups(:assets => %w(development test))

For more info regarding Bundler and groups, read http://bundler.io/v1.5/groups.html