Refactored version of Chef RPM packages plugin; also expanded to handle dpkgs. Original source code: https://github.com/demonccc/chef-repo/blob/master/plugins/ohai/linux/rpm.rb

packages.rb

#
# Author:: Claudio Cesar Sanchez Tejeda <demonccc@gmail.com>
# Author:: Julian C. Dunn <jdunn@chef.io>
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
## See the License for the specific language governing permissions and
# limitations under the License.
#

Ohai.plugin(:Packages) do
  provides "linux/packages"
  depends "platform"

  collect_data(:default) do
    packages Mash.new
    if %w{ rhel fedora suse }.include?(platform_family) or %w{ redhat fedora centos suse }.include?(platform)
      so = shell_out("rpm -qa --queryformat '%{NAME} %{VERSION} %{RELEASE}\n'")
      so.stdout.lines do |line|
        fields = line.split(/\s+/)
        packages[fields[0]] = { 'version' => fields[1], 'release' => fields[2] }
      end
    elsif %w{ debian }.include?(platform_family)
      so = shell_out("dpkg-query -W -f='${Package} ${Version}\n'")
      so.stdout.lines do |line|
        fields = line.split(/\s+/)
        packages[fields[0]] = { 'version' => fields[1] }
      end
    end
  end
end