docker-tags.rb

require "JSON"

def get_json(url)
  print "Fetching `#{url}`... "
  result = `curl -s "#{url}"`
  puts "DONE"
  JSON.parse(result, :symbolize_names => true)
end

def get_tags(image)
  tags = []
  url = "https://hub.docker.com/v2/repositories/#{image}/tags/"
  
  while url do
    result = get_json(url)
    
    tags += result[:results].map { |result| result[:name]}

    url = result[:next]
  end

  tags
end

# eg. gitlab/gitlab-ce
# get_tags("gitlab/gitlab-ce")