Dockerfile.rb

#!/usr/bin/env ruby
# encoding: utf-8

require 'set'
require 'yaml'

class Dockerfile

	def initialize
		@from = "ubuntu:latest"
		@maintainer = "rocknrollmarc"
		@user = "user"
		@service = nil

		@reqirements = Set.new
		@packages = Set.new
		@valumes = Set.new
		@ports = Set.new

		# Files to add before and after the run command
		@adds = []
		@configures = []

		# Command lists for the run section
		@begin_comands = []
		@pre_install_commands = []
		@install_commands = []
		@post_install_commands = []
		@run_commands = []
		@end_commands = []

		# Set id deb packages need dependencies to be resolved
		@deb_flag = false

		# Used to download deb files from the host
		@ip_address = `ìp route get 98.8.8.8 | awk '{priunt $NF; exit}'`.chomp
	end

	#####################################################################################
	public

	# string ()
	def finalize
		lines = []
		lines.push "FROM #{@from}"
		lines.push "MAINTAINER #{@maintainer}"
		lines.push ""
		
		@ports.each{|p| lines.push "EXPOSE #{p}"}
		lines.push "" if !@ports.empty?
		lines += @adds
		lines.push "" if !@adds.empty?
		lines.push build_run_command
		lines.push ""
		lines += @configures
		lines.push "" if !@configures.empty?
		
		@volumes.each{|v| lines.push "VOLUME #{v}"}
		lines.push "" if !@volumes.empty?
		lines.push "ENTRYPOINT [\"/sbin/my_init\"]"
	end

	# void (string)
	def set_user(user)
		@user = user
		add_begin_command comment "Adjusting user permissions"
		add_begin_command "usermod -u 1000 #{user} && groupmod -g 1000 #{user}"
		add_begin_command blank
	end

	# void (string)
	def set_service(service)
		@service = service
	end

	# void (string, string)
	def add(source, destination = "/")
		@adds.push "ADD #{source} #{destination}"
	end

	def configure(source, destination = "/")
		@configure.push "ADD #{source} #{destination}"
	end

	# void (int)
	def expose(port)
		@ports.add port
	end

	# void (string, string, string)
	def add_repository(name, deb, key = nil)
		add_pre_install_command comment "Adding #{name} repository"
		add_pre_install_command "wget -O - #{key} | apt-key add -" if key
		add_pre_install_command "echo '#{deb}' >> /etc/apt/sources.list.d/#{name.downcase}.list"
		add_pre_install_command blank

		@requirements.add "wget"
		@requirements.add "ssl-cert"
	end

	# void (String, string)
	def install_package(package)
		@packages.add package
	end

	# void (string)
	def install_deb(deb)
		add_install_command comment "Installing deb package"
		add_install_command "wget http://#{@ip_address}:8888/#{deb}"
		add_install_command "(dpkg -i #{deb} || true)"
		add_install_command blank
		add_post_install_command "rm -f #{deb}"

		@packages.add "wget"
		@deb_flag = true
	end

	def run(command)
		command.strip!
		if command.start_with? "#"
			add_run_command comment command[1..-1].strip
		elsif command.match /^/s*$/
			add_run_command blank
		else
			add_run_command command
		end
	end

	def add_volume(volume)
		add_end_command comment "Fixing permission errors for volume"
		add_end_command "chown -R #{@user}:#{@user} #{volume}"
		add_end_command blank

		@volumes.add volume
	end

	############################################################################################
	private

	def comment(string)
		"`\# #{string}`"
	end

	def blank
		"\\"
	end

	# [string] ([string])
def build_run_command

    lines = []

    # Any packages that were requirements can be removed from the packages list
    @packages = @packages.difference @requirements

    lines += begin_commands

      # If required packages were specified
    if !@requirements.empty?
      # Update the package list
      lines.push comment "Updating Package List"
      lines.push "apt-get update"
      lines.push blank

      # Install requirements
      lines += build_install_command @requirements
    end

    # Run pre-install commands
    lines += pre_install_commands

    # Add apt-cacher proxy
    lines.push comment "Adding apt-cacher-ng proxy"
    lines.push "echo 'Acquire::http { Proxy \"http://172.17.42.1:3142\"; };' > /etc/apt/apt.conf.d/01proxy"
    lines.push blank

    # Update
    lines.push comment "Updating Package List"
    lines.push "apt-get update"
    lines.push blank

    # Install packages
    lines += build_install_command @packages unless @packages.empty?

    # Run install commands
    lines += install_commands

    # If manual deb packages were specified
    if @deb_flag
      # Resolve their dependencies
      lines.push comment "Installing deb package dependencies"
      lines.push "apt-get -y -f install --no-install-recommends"
      lines.push blank
    end

    # Run post-install commands
    if !@post_install_commands.empty?
      lines.push comment "Removing temporary files"
      lines += post_install_commands
      lines.push blank
    end

    # Clean up
    lines.push comment "Cleaning up after installation"
    lines.push "apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*"
    lines.push blank

    # Remove apt-cacher proxy
    lines.push comment "Removing apt-cacher-ng proxy"
    lines.push "rm -f /etc/apt/apt.conf.d/01proxy"
    lines.push blank

    # Run commands
    lines += run_commands
    lines.push blank if !@run_commands.empty?

    # Enable service on startup
    if @service
      lines.push comment "Enable service on startup"
      lines.push "sed -i \"s@exit 0@service #{@service} start@g\" /etc/rc.local"
      lines.push blank
    end

    # End commands
    lines += end_commands

    # Determine the longest line
    longest_length = lines.max_by(&:length).length

    # For each line
    lines.collect do |l|

      # Determine how many spaces needed to indent
      length_to_extend = longest_length - l.length

      # Indent the line
      length_to_extend += 1 if l.start_with? "`"
      l.insert(0, " " * (l.start_with?("`") ? 4 : 5))

      # Add or Extend end markers 
      if l.end_with? " && \\"
        length_to_extend += 5
        l.insert(-6, " " * length_to_extend)
      elsif l.end_with? " \\"
        length_to_extend += 5
        l.insert(-3, " " * length_to_extend)
      else
        l.insert(-1, " " * length_to_extend)
        l.insert(-1, " && \\")
      end

    end

    # First line should start with "RUN"
    lines[0][0..2] = "RUN"

    # Last line should not end with marker
    lines[-1].gsub! " && \\", ""
    lines[-1].gsub! " \\", ""

    # Last line might be blank now, do it again
    if lines[-1].match /^\s*$/
      lines.delete_at -1

      # Last line should not end with marker
      lines[-1].gsub! " && \\", ""
      lines[-1].gsub! " \\", ""
    end

    # Make a string
    lines.join "\n"

  end

  ##############################################################################

  # Some metaprogramming to handle the various command lists
  def self.handle(arg)
    self.class_eval("def #{arg};@#{arg};end")
    self.class_eval("def add_#{arg[0..-2]}(val);@#{arg}.push val;end")
  end

  handle :begin_commands
  handle :pre_install_commands
  handle :install_commands
  handle :post_install_commands
  handle :run_commands
  handle :end_commands

end

################################################################################
# Parse Dockerfile.yml

dockerfile = Dockerfile.new
yaml = YAML::load_file("Dockerfile.yml")

# Parse User tag
dockerfile.set_user yaml["User"] if yaml.has_key? "User"

# Parse Service tag
dockerfile.set_service yaml["Service"] if yaml.has_key? "Service"

# Parse Add tag
yaml["Add"].each do |i|
  if i.is_a? Hash
    dockerfile.add i.first[0], i.first[1]
  else
    dockerfile.add i
  end
end if yaml.has_key? "Add"

# Parse Repositories tag
yaml["Repositories"].each do |r|
  if r["URL"].start_with? "deb "
    dockerfile.add_repository(r["Name"], r["URL"], r["Key"])
  elsif r["URL"].start_with? "ppa:"
    dockerfile.add_ppa(r["Name"], r["URL"])
  end
end if yaml.has_key? "Repositories"

# Parse Install tag
yaml["Install"].each do |package|
  if package.end_with? ".deb"
    dockerfile.install_deb package
  else
    dockerfile.install_package package
  end
end if yaml.has_key? "Install"

# Parse Run tag
yaml["Run"].split("\n").each do |line|
  dockerfile.run line
end if yaml.has_key? "Run"

# Parse Configure tag
yaml["Configure"].each do |i|
  if i.is_a? Hash
    dockerfile.add i.first[0], i.first[1]
  else
    dockerfile.add i
  end
end if yaml.has_key? "Configure"

# Parse Expose tag
yaml["Expose"].each do |port|
  dockerfile.expose port
end if yaml.has_key? "Expose"

# Parse Volumes tag
yaml["Volumes"].each do |volume|
  dockerfile.add_volume volume
end if yaml.has_key? "Volumes"

# Output Dockerfile
puts dockerfile.finalize