Clean untagged Docker images and zombie containers

clean-images.rb

#!/usr/bin/env ruby
# Description: Sometimes after building, starting and killing a number of
# docker containers over time, you end up with images that cannot be removed
# removed because zombie containers are referencing them. This removes all
# images of a given name or untagged images and the container that 
# reference them.
#
# Disclaimer: This is recommended for development environments only.
# Frivolous usage may result in unintended data loss.
#
# Usage: clean-images image_name

# Name of the image to remove. Default is all untagged (labeled <none>) images.
image_name = ARGV[0] || "<none>"

begin
  # Attempt to remove all images of the specified name.
  output = `sudo docker rmi $(sudo docker images | grep "#{image_name} " | awk '{print($3)}') 2>&1`
  puts output

  # Find images that could not be removed because a container references them.
  containers = output.scan(/Conflict, cannot delete [a-f0-9]+ because the container ([a-f0-9]+) is using it/)
  # Remove each of these containers and repeat until all untagged images are gone.
  containers.each do |container|
    puts "Removing #{container[0]}"
    puts `sudo docker rm #{container[0]}`
  end
end while containers.length > 0
puts "Finished"