ubuntu-cloud-images.rb

#!/usr/bin/env ruby

begin
  require 'multi_json'
  require 'rexml/document'
  require 'terminal-table'
rescue LoadError => e
  abort "Unable to load library: #{e.message}"
end

require 'net/http'
require 'open-uri'

class Release
  CACHE = File.expand_path('~/.ubuntu-cloud-images.json')
  TABLE = 'http://cloud-images.ubuntu.com/locator/ec2/releasesTable'

  attr_accessor :region, :suite, :version, :arch, :type, :date, :ami, :aki, :launch

  def initialize(data)
    data.each do |k,v|
      send("#{k}=", v) if respond_to?("#{k}=")
    end
  end

  def to_a
    self.class.row_format.map {|x| send(x)}
  end

  def =~(filters)
    filters.all? {|key, value| send(key) == value}
  end

  def self.row_format
    # ['region', 'suite', 'version', 'arch', 'type', 'date', 'ami', 'aki', launch']
    ['region', 'suite', 'arch', 'type', 'date', 'ami', 'launch']
  end

  def self.by_attributes(filters = {})
    all.select {|x| x =~ filters}
  end

  def self.all
    get_releases
    MultiJson.load(File.read(CACHE)).map {|release| new(Hash[self.row_format.zip(release)])}
  end

  def self.get_releases
    return if cache_up_to_date?
    releases = open(TABLE).read
    releases[releases.rindex(',')] = ''
    keypair = ENV['EC2_KEYPAIR_NAME'] || 'EC2_KEYPAIR_NAME'
    data = MultiJson.load(releases)['aaData']
    data.each do |row|
      row[6] = REXML::Document.new(row[6]).elements.first.text
      row.push("ec2-run-instances -k #{keypair} #{row[6]}")
      row.delete_at(7)
      row.delete_at(2)
    end
    File.open(CACHE, 'w') {|f| f.write(MultiJson.dump(data))}
  end

  def self.cache_up_to_date?
    File.exists?(CACHE) && (File.mtime(CACHE).to_date > releases_last_modified)
  end

  def self.releases_last_modified
    response = nil
    uri = URI(TABLE)
    Net::HTTP.start(uri.host, 80) {|http| response = http.head(uri.path)}
    DateTime.parse(response['last-modified'])
  end
end

if __FILE__ == $0
  filters = {}
  ARGV.each do |arg|
    k,v = arg.split(':')
    filters[k] = v
  end
  if filters.empty? || filters.values.any? {|x| x.nil?}
    abort "Usage: #{__FILE__} field:value [ field:value [ field:value [...]]]"
  end
  STDOUT.puts(Terminal::Table.new :headings => Release.row_format, :rows => Release.by_attributes(filters).map(&:to_a))
end