Puppet Module Gems

Description - What this utility does and why it is useful
Setup - The basics of getting started with Puppet Module Gems
- Setup requirements
Usage - Configuration options and additional functionality
Reference - An under-the-hood peek at what the module is doing and how
Limitations - OS compatibility, etc.
Support

Description

Puppet Module Gems is a utility that generates gemspecs and builds management gems based on a YAML-based configuration. The purpose for these gems is to reduce the amount of changes required to sync shared dependencies across multiple modules’ Gemfiles.

For example, when a dependency gem publishes a new release that requires Ruby 2.3.3, this would normally break all modules that install this gem that run on a version of Ruby less than 2.3.3. To fix this previously, you would need a modulesync to pin the gem to a compatible version. With these new gem management gems, you can instead update the gem version pin in a configuration YAML. The gem management will then build and publish to rubygems, and a bundle update fixes all affected modules.

Setup

Setup Requirements

Requires Ruby version 2.0 or greater
Requires RubyGems gem version 2.0 or greater
Requires Bundler gem version 1.3.0 or greater

Usage

To get started using this utility, first clone this git repository:

git clone git@github.com:puppetlabs/puppet-module-gems.git

Install the development gems:

bundle install

Building the gems

To build the gems with the default configuration, execute the script bundle exec exe/puppet-module-gems.rb. The gemspec files and gems will be generated in the pkg directory.

Customizing dependency gems

To build customized dependency gems, you simply need to modify the config yamls prior to running the script.

First modify the config/info.yml to customize the prefix for your gem names, in addition to the rest of the required information. Secondly, you will need to modify the config/dependencies.yml to customize the dependency matrix to suit your needs. After defining these customizations, you can build your gems with the directions detailed in Building the gems.

Using generated gems

To use the resulting gems, replace the sections of the Module Gemfile with the appropriate gems and conditions.

For Example:

group :development do
  gem 'puppet-lint',                        :require => false
  gem 'metadata-json-lint',                 :require => false, :platforms => 'ruby'
  gem 'puppet_facts',                       :require => false
  gem 'puppet-blacksmith', '>= 3.4.0',      :require => false, :platforms => 'ruby'
  gem 'puppetlabs_spec_helper', '>= 1.2.1', :require => false
  gem 'rspec-puppet', '>= 2.3.2',           :require => false
  gem 'rspec-puppet-facts',                 :require => false, :platforms => 'ruby'
  gem 'mocha', '< 1.2.0',                   :require => false
  gem 'simplecov',                          :require => false, :platforms => 'ruby'
  gem 'rubocop',                            :require => false
  gem 'pry',                                :require => false
  gem 'rainbow', '< 2.2.0',                 :require => false
end

group :system_tests do
  gem 'beaker-puppet_install_helper',                                            :require => false
  gem 'beaker-module_install_helper',                                            :require => false
  gem 'master_manipulator',                                                      :require => false
end

The above Gemfile section would become:

# calculate the correct package names from the current ruby version
ruby_version_segments = Gem::Version.new(RUBY_VERSION.dup).segments
minor_version = "#{ruby_version_segments[0]}.#{ruby_version_segments[1]}"

gem "puppet-module-posix-default-r#{minor_version}"

group :development do
  gem "puppet-module-posix-dev-r#{minor_version}"
end

group :system_tests do
  gem "puppet-module-posix-system-r#{minor_version}"
end

After this update, the subsequent bundle install or bundle update would pull in the new gems and the dependencies should reflect the correct version bindings based on the Ruby version. Any future gems and version pinning that may be needed can be done via publishing updated management gems.

Reference

Configuration Files

info.yml

Reserved Keys

info - Details the start of the information block. Required.
prefix - Indicates the prefix to use for the generated gems. Required.

Required Keys

authors - String. The author of these gems.
email - String. Email address of the author.
homepage - String. Homepage for the gem project.
licenses - String. License to publish gems under.
summary - String. Brief description of what the gem does.
version - String. Version of these gems.

dependencies.yml

Reserved Keys

dependencies - Details the start of the dependencies block. Required.
shared - Details the shared dependencies amongst the keys within the same tier.
gem - Details the name of the gem dependency to add. Required.
version - Details the version bindings for the gem listed in preceding gem.

Example

dependencies:
  shared:
    a:
      - gem: shared-gem
        version: '> 1.0.0'
  first:
    a:
      - gem: a-gem-one
    b:
      - gem: b-gem-one
        version: '< 2.0.0'
  second:
    b:
      - gem: b-gem-two

The above dependency matrix will generate this list of gems if the defined prefix is test-gem with version 1.0.0:

test-gem-first-a-1.0.0.gem
test-gem-first-b-1.0.0.gem
test-gem-second-a-1.0.0.gem
test-gem-second-b-1.0.0.gem

And for example, the gemspec for test-gem-first-a-1.0.0.gem will include dependencies of:

shared-gem, '> 1.0.0'
a-gem-one

Limitations

Use of this utility has only been tested on Linux and OS-X platforms.

Support

This utility is maintained and developed by the Puppet SDK and Puppet Modules team. Please file an issue for support. Contributions are also welcomed!

wilson208/puppet-module-gems