rpm_helper.rb

require 'yaml'
require 'erb'
require 'fileutils'

require 'primedia/rpm_defaults'

module Primedia
  class RpmHelper
    include Rake::DSL if defined? Rake::DSL

    class << self
      # set when install'd.
      attr_accessor :instance

      def install_tasks(opts = {})
        new(opts[:name]).install
      end

    end

    attr_reader :spec_path

    def initialize(name = nil)
    end

    def install(name = nil, version = nil, release = nil)
      namespace :rpm do
        desc "Build #{name}-#{version}-#{release}.rpm into the pkg directory."
        task :build do
          build(name, version, release)
        end
      end
    end

    private

    def build(name, version, release)
      if File.exists?(config_file)
        user_config = YAML.load_file(config_file)
      else
        fail "Must provide a config/rpm.yml file."
      end

      if File.exists?(build_info_file)
        build_info = YAML.load_file(build_info_file)
      else
        fail "Must provide a BUILD_INFO file."
      end

      # opts is used by the ERB template which has access to it due to being passed the current binding.
      opts = Primedia::RpmDefaults::SPEC_DEFAULTS.merge(user_config)

      opts['version']  = build_info['version'].gsub('_','.')
      opts['revision'] = short_sha(build_info['revision'])

      app_name = opts['app']['name']

      filename = "#{app_name}.spec"

      build_root = "/tmp/rpmbuild-#{app_name}-#{opts['revision']}"

      %w(BUILD RPMS SOURCES SPECS SRPMS).each do |build_dir|
        FileUtils.mkdir_p(File.join(build_root, build_dir))
      end

      File.open("#{build_root}/SPECS/#{filename}", 'w') do |f|
        f.write( spec_template.result(binding) )
      end

      FileUtils.cp build_info['artifact_name'], "#{build_root}/SOURCES/#{app_name}.tar.gz"

      Bundler.clean_system("rpmbuild --define '_topdir #{build_root}' -ba #{build_root}/SPECS/ag.spec")

    end

    def config_file
      @config_file ||= File.join(Rake.application.original_dir, 'config/rpm.yml')
    end

    def build_info_file
      @build_info_file ||= File.join(Rake.application.original_dir, 'BUILD_INFO')
    end

    def spec_template
      @spec_template ||= ERB.new(File.read(spec_template_file))
    end

    def spec_template_file
      @spec_template_file ||= File.expand_path('../templates/ruby.spec.erb', __FILE__)
    end

    def date_as_version
      # e.g. 2013.12.31
      Time.now.strftime("%Y.%m.%d.%H.%M")
    end

    def short_sha(revision)
      revision[0,6]
    end
  end
end

ruby.spec.erb

# RPM Spec File for Ruby Application deployment via RPM
#
# by Colin Rymer, 2013-12-03
#
# Inspired by:
#     RPM Spec File for Rails Application deployment via RPM
#     by Tilo Sloboda, 2012-10-17
#
# We should use a separate build user, not root, to create the RPMs
#
Name: <%= opts['app']['name'] %>
Version: <%= opts['version'] %>
Release: <%= opts['revision'] %>
Summary: <%= "#{opts['app']['name']}-#{opts['version']}-#{opts['revision']}" %>
Group: Applications/Internet
License: Proprietary
URL:  <%= opts['app']['url'] %>
# AutoReqProv: see doc!!! we don't want shared libraries to the dependencies
AutoReqProv: no
ExclusiveArch: x86_64
ExclusiveOS: linux
Provides: <%= "#{opts['app']['name']} = #{opts['version']}" %>

BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)

# List of all tools needed to BUILD the RPM:
# this also needs to list required YUM / RPM packages, such as shared libraries specific for the application!!
<% opts['app']['build_requires'].each do |req| %>
BuildRequires: <%= req %>
<% end if opts['app']['build_requires'] %>

# REQUIREMENTS:
Requires: chruby-ruby = <%= opts["app"]["ruby_version"] %>
<% opts['app']['requires'].each do |req| %>
Requires: <%= req %>
<% end if opts['app']['requires'] %>

Source: <%= opts['app']['name'] %>.tar.gz

# No debuginfo rpm creation, etc.
%global debug_package %{nil}

%define deploy_user <%= opts['deploy']['user'] %>
%define deploy_group <%= opts['deploy']['group'] %>

%description
<%= opts['app']['description'] %>

# run after RPM is built
%clean
 rm -rf $RPM_BUILD_ROOT

# run before RPM is built:
%prep
%setup -q -c

%build
 bundle install --deployment --without <%= opts["app"]["bundle_without"].join(' ') %>

 # these files are not needed for the deployment:
 <% opts['app']['exclude'].each do |file| %>
   <%= "rm -rf #{file}" unless file.start_with?('/') %>
 <% end %>

# HOOK for installing the compiled bits into a directory structure which will then be bundled up into the actual RPM:
%install
 mkdir -p %{buildroot}/var/log/%{name} %{buildroot}/var/www/%{name} %{buildroot}/var/run/%{name}
 cp -R ./ %{buildroot}/var/www/%{name}

# Manifest of all Files which are part of the RPM:
%files
%defattr(-,%{deploy_user},%{deploy_group},0755)
/var/www/%{name}
%config %ghost /var/log/%{name}
%config %ghost /var/run/%{name}