gistfile1.txt

#
# Author:: Tim Dysinger (<tim@dysinger.net>)
# Author:: Benjamin Black (<bb@opscode.com>)
# Author:: Christopher Brown (<cb@opscode.com>)
# Copyright:: Copyright (c) 2009 Opscode, Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

require 'open-uri'
require 'socket'
include Socket::Constants

require_plugin "hostname"
require_plugin "kernel"
require_plugin "virtualization"
require_plugin "network"

EC2_METADATA_URL = "http://169.254.169.254/2008-02-01/meta-data"

def can_metadata_connect?(addr, port, timeout=2)
  t = Socket.new(AF_INET, SOCK_STREAM, 0)
  saddr = Socket.pack_sockaddr_in(port, addr)
  connected = false

  begin
    t.connect_nonblock(saddr)    
  rescue Errno::EINPROGRESS
    IO::select(nil,[t],nil,timeout)
    begin
      t.connect_nonblock(saddr)
    rescue Errno::EISCONN
      t.close
      connected = true
    rescue SystemCallError
    end
  rescue SystemCallError
  end

  connected
end

def has_ec2_mac?
  network[:interfaces].values.each do |iface|
    unless iface[:arp].nil?
      return true if iface[:arp].value?("fe:ff:ff:ff:ff:ff")
    end
  end
  false
end

def metadata(id='')
  # Try non-blocking connect with lite spin so we don't "block" if 
  # the Xen environment is *not* EC2
  OpenURI.open_uri("#{EC2_METADATA_URL}/#{id}").read.split("\n").each do |o|
    key = "#{id}#{o.gsub(/\=.*$/, '/')}"
    if key[-1..-1] != '/'
      ec2[key.gsub(/\-|\//, '_').to_sym] =
        OpenURI.open_uri("#{EC2_METADATA_URL}/#{key}").gets
    else
      metadata(key)
    end
  end
end

def looks_like_ec2?
  virtualization[:system] == "xen" &&  virtualization[:role] == "guest" && has_ec2_mac? && can_metadata_connect?
end

if looks_like_ec2?
  ec2 Mash.new
  self.metadata
end