Rack::AppVersion Middleware

Rack::AppVersion is a middleware that sets the version of an app (Rack compatible web applications) via response header.

Setup

1. In your Gemfile

gem 'rack-app_version'

2. In config/application.rb of your Rails application, put the code below.

module YourApp
  class Application < Rails::Application

    # ...

    config.middleware.use Rack::AppVersion

  end
end

3. In Rakefile of your Rails application, put the code below.

module Rack
  class AppVersion
    def self.generate_version
      # Implement logic of getting application version here.
    end
  end
end

require 'rack/app_version/rake_task'
Rack::AppVersion.load_tasks

Doing bundle exec rake -T | grep app_version will give you the following which you can use:

rake app_version:generate               # generate app version and write it in .app_version file
rake app_version:init                   # generate .app_version file that will contain application version

4. Use have_app_version matcher to ensure everything is setup (optional).

This rspec matcher can be used by the application to ensure that everything is properly configured.

it 'has app version in response headers' do
  expect(env).to have_app_version
end

Common Gotchas

To determine where to put the Rack::AppVersion middleware in the Rack stack, run the following command:

bundle exec rake middleware

In many cases, the Rack stack will be different running in production environment. Run the following command to see the middleware stack in production:

RAILS_ENV=production bundle exec rake middleware

See The Rails Guide to Rack for more details on rack middlewares or watch the railscast.