virsh-define.rb

#!/usr/bin/env ruby

require 'erb'
require 'tempfile'
require 'shellwords'
require 'logger'

module Libvirt
  class ERBContext
    def initialize logger
      @logger = logger
    end

    def include file
      @logger.info "including `#{file}`"
      File.read file
    end

    def get_binding
      binding
    end
  end
end

raise "usage: #$0 input.xml.erb" unless ARGV.length == 1

# Create a logger
name = File.basename(__FILE__).freeze
logger = Logger.new STDERR
logger.progname = name

# Evaluate the erb
erb = File.realpath ARGV.first
logger.info "evaluating `#{erb}`"
xml  = ERB.new(File.read(erb)).result Libvirt::ERBContext.new(logger).get_binding

# Create a tempfile
tmp  = Tempfile.new name
tmp.sync = true

begin
  # Write the XML
  logger.info 'defining domain'
  tmp.write xml

  # Define it through virsh
  result = `#{%W[virsh define #{tmp.path}].shelljoin}`
  result = "virsh (#{$?.exitstatus}): #{result.strip}"

  if $?.exitstatus == 0
    logger.info result
  else
    logger.error result
  end
ensure
  # Close it out
  tmp.close unless tmp.closed?
  tmp.unlink
end

# Exit, using the status from virsh
exit $?.exitstatus