docker-build

#!/usr/bin/env ruby

require 'docker-api'
require 'fileutils'
require 'open3'
require 'optparse'
require 'pathname'
require 'tmpdir'

DEFAULT_IMAGE_NAME = ''

Dockerfile = Struct.new(:name, :lines)

def extract(container, source_file, destination_directory)
  destination = destination_directory / source_file
  destination.dirname.mkpath
  Open3.popen2('tar', 'x', '-C', destination.dirname.to_s) do |tar_in, tar_out|
    container.copy(source_file.to_s) do |chunk|
      tar_in << chunk
    end
    tar_in.close
    tar_out.close
  end
end

tags = {}
OptionParser.new do |opts|
  opts.banner = "Usage: #{$0} [options] PATH"

  opts.on '-tTAG', '--tag=TAG', 'Image tag, in the format <DOCKERFILE-NAME>=<NAME>:<TAG>' do |tag|
    image_name, tag_name = tag.split('=', 2)
    if tag_name.nil?
      image_name, tag_name = [DEFAULT_IMAGE_NAME, image_name]
    end
    tags[image_name] = tag_name
  end
end.parse!

path = Pathname.new(ARGV[0]).expand_path
parent_dockerfile = (path / 'Dockerfile').readlines
dockerfiles = parent_dockerfile
  .slice_when { |before, after|
    after.start_with?('NAME ') || (!before.start_with?('NAME ') && after.start_with?('FROM '))
  }.collect { |dockerfile|
    dockerfile.unshift('NAME ' + DEFAULT_IMAGE_NAME) unless dockerfile[0].start_with?('NAME ')
    name_line, *lines = dockerfile
    name = name_line[5, name_line.length].strip
    Dockerfile.new(name, lines)
  }

images = {}

failed = false

dockerfiles.each do |dockerfile|
  next if failed

  lines = []
  image_files = {}
  dockerfile.lines.each do |line|
    if line =~ /^COPY (\w+):\/(.+?) (.+)$/m
      image_files[$1] ||= []
      image_files[$1] << $2
      lines << "COPY .containers/#{$1}/#{$2} #{$3}"
    else
      lines << line
    end
  end
  dockerfile.lines = lines

  Dir.mktmpdir do |dir_string|
    dir = Pathname.new(dir_string)

    (dir / '.containers').mkdir unless image_files.empty?
    image_files.each do |image_name, files|
      container = Docker::Container.create('Image' => images[image_name].id, 'Cmd' => ['true'])
      destination_directory = dir / '.containers' / image_name

      begin
        container.start
        files.each do |file|
          extract container, file, destination_directory
        end
      ensure
        container.delete
      end
    end

    FileUtils.cp_r "#{path}/.", dir.to_s
    (dir / 'Dockerfile').write(dockerfile.lines.join)

    begin
      images[dockerfile.name] = Docker::Image.build_from_dir(dir_string) do |streaming_lines|
        streaming_lines.each_line do |line|
          log = JSON.parse(line)
          if log && log.has_key?('stream')
            print log['stream']
          elsif log.has_key?('errorDetail')
            puts log['errorDetail']['message']
          end
        end
      end
    rescue Docker::Error::UnexpectedResponseError
      failed = true
    end
  end
end

images.each do |image_name, image|
  if tags[image_name]
    image.tag('repo' => tags[image_name])
  end
end

exit 1 if failed