Rake command to sync files in host to container

docker.rake

require 'docker'
require 'listen'

APP_NAME =  'hoge'

def retrieve_file(app_root, file)
  dir = File.dirname(file)
  container_dir = dir.to_s.sub(Regexp.new(app_root + '/'), '')
  container_file = file.to_s.sub(Regexp.new(app_root + '/'), '')
  return container_dir, container_file
end

def exec(container, args)
  std_out, std_err, _ = container.exec(args)
  puts std_out if std_out
  puts std_err if std_err
end

def get_app_container
  Docker::Container.all.find {|container| Regexp.new(APP_NAME).match?(container.info['Image'])}
end

namespace :docker do
  desc 'sync files from host'
  task sync: :environment do
    ignore_patterns = %w(Gemfile.lock)
    app_root = Rails.root.to_s
    app_root_in_container = '/var/www/brabrabra'
    app_container = get_app_container
    if app_container.nil?
      puts "Error: docker container not found: #{APP_NAME}"
      return
    end
    listener = Listen.to('.') do |modified, added, removed|
      ([*modified, *added]).each do |file|
        container_dir, container_file = retrieve_file(app_root, file)
        if ignore_patterns.include?(container_file)
          puts "ignore file: #{container_file}"
          next
        end
        dir, errors, _ = app_container.exec(['ls', container_dir])
        if dir.length.zero? and errors.length > 0
          app_container.exec(['mkdir', '-p', container_dir])
        end
        `docker cp #{file} #{app_container.id}:#{app_root_in_container}/#{container_file}`
        puts "updated: #{container_file}"

        if container_file.eql?('Gemfile')
          exec(app_container, %w(bundle install))
        end
      end

      removed.each do |file|
        _, container_file = retrieve_file(app_root, file)
        exec(app_container, ['rm', '-v', container_file])
      end
    end
    listener.start
    sleep
  end

  desc 'execute a command in container'
  task :exec, ['command'] => :environment do |task, args|
    exec(get_app_container, args[:command].split(' '))
  end
end