Robust ec2 meta-data collection

robust_ohai_ec2.rb

# Ohai Eec2 meta-data collections and `looks_like_ec2?`
# were broken in at least: 0.6.4 and 0.6.10
#
# Invitation for wrath of the G-ds:
# This gist always seems to have worked to extract (some?/all?) meta-data
#
# Aslo allows us to avoid #all_plugins, which has needed wait functionality.
# See:
# http://www.danpisarski.com/2010/08/22/loading-only-the-data-you-want-in-ohai/
#
# Usage:
# o = ::Ohai::System.new
# o.require_plugin('ec2')
# o.wait_on_children

require 'ohai'

class ::Ohai::System
  def wait_on_children
    unless RUBY_PLATFORM =~ /mswin|mingw32|windows/
      # Catch any errant children who need to be reaped
      begin
        true while Process.wait(-1, Process::WNOHANG)
      rescue Errno::ECHILD
      end
    end
  end
end


o = ::Ohai::System.new
o.require_plugin('ec2')
o.wait_on_children
if o.looks_like_ec2?
  ec2_data = o[:ec2]
else
  # Ohai 0.6.4 is broken so we can't use the above.
  begin
    ec2_data = o.fetch_metadata
  rescue Errno::EHOSTUNREACH
    ec2_data = {}
  end
end
ec2_data