[:octopus:] Test for Docker remote repository compatibility with old clients

registry-compat-test.rb

#!/usr/bin/env ruby
# ruby registry-compat-test.rb namespace/repo

require 'faraday'
require 'json'

REPO = ARGV[0].split(':')[0]
TAG = ARGV[0].split(':')[1] || 'latest'

# Fetch image list and X-Docker-Token
images_url = "https://index.docker.io/v1/repositories/#{REPO}/images"
images_request = Faraday.new(url: images_url)
images_response = images_request.get do |req|
  req.headers['X-Docker-Token'] = 'true'
end
images = JSON.parse(images_response.body).map { |entry| entry['id'] }
token = images_response.headers['X-Docker-Token']

tag_layers_url = "https://index.docker.io/v1/repositories/#{REPO}/tags/#{TAG}"
tag_layers_request = Faraday.new(url: tag_layers_url)
tag_layers_response = tag_layers_request.get
layers = JSON.parse(tag_layers_response.body).map { |entry| entry['id'] }
layer_images = layers.map { |layer| images.find { |id| id =~ /^#{layer}/ } }

repo_compatible = true
layer_images.each do |id|
  layer_url = "https://registry-1.docker.io/v1/images/#{id}/layer"
  layer_request = Faraday.new(url: layer_url)
  layer_response = layer_request.get do |req|
    req.headers['Authorization'] = "Token #{token}"
  end
  path = layer_response.headers['Location'].split('/')[3]
  puts "#{id[0..11]}: #{path}"
  repo_compatible = false unless path == 'images'
end
puts "Compatibility: #{repo_compatible ? 'GOOD' : 'BAD'}"