Convert a folder of source ruby gems into debs

Rakefile

# When in a folder with ruby gem source folders underneath it, running this will
# build each gem, install it and it's dependencies to a temporary folder and finally
# convert the gems and all it's dependencies into debian packages.

GEM_PREFIX = "/usr/lib/gems/2.1.4"
GEMS       = ["redis_alerting", "rackdis"]

namespace :gems do

  task :pkg do
    puts "Building and install required gems to temp folder".bold.blue

    FileUtils.rm_rf "/tmp/gems"
    FileUtils.mkdir "/tmp/gems"

    GEMS.each do |dir|
      gemname = ""

      FileUtils.chdir dir do
        gemname = `rake build`.chomp.split("/").last[0..-2]
        abort "Building #{dir} failed...".bold.red unless $?.success?
        system "rake install >/dev/null"
        abort "Installing #{dir} locally failed...".bold.red unless $?.success?
      end

      gempkg = "./#{dir}/pkg/#{gemname}"
      abort "Couldn't find #{gempkg}!".bold.red unless File.exist? gempkg

      system "gem install --no-ri --no-rdoc --install-dir /tmp/gems #{gempkg}"

      abort "Installing gem to temp folder failed...".bold.red unless $?.success?
      puts "* Built and installed #{dir} to tmp folder".bold.green
    end

    puts "\nConverting gems to debian packages...".bold.blue

    Dir["/tmp/gems/cache/*.gem"].each do |pkg|
      system "fpm --log error -f -a all -d ruby --prefix #{GEM_PREFIX} -s gem -t deb #{pkg} >/dev/null"
      puts "* #{File.basename(pkg)} converted to debian package".bold.green if $?.success?
    end

    puts ""

  end

end