Learning MCollective

Chapter 22. Collecting Responses

One of the features that makes MCollective truly unique is the ability to send requests from one client and to process the responses with a different client or listener, as shown in Figure 22-1.

Figure 22-1. A separate listener to process results from requests

Create a Listener

The first thing we’ll do here is to create a listener. What I’ll introduce to you here is a working listener from which you can debug any problem. You can also copy it and add new functionality. I put my listeners in the $libdir directory just like every other plugin, but that’s not required:

$ cat /usr/libexec/mcollective/mcollective/listener/debugger.rb # Parse options, load config, and start an MCollective client. require 'mcollective' optparser = MCollective::Optionparser.new options = optparser.parse config = MCollective::Config.instance config.loadconfig(options[:config]) MCollective::PluginManager["security_plugin"].initiated_by = :client connector = MCollective::PluginManager['connector_plugin'] connector.connect # Get pretty-print and the Log object require 'pp' Log = MCollective::Log # Get a reply queue name from command line, default to "debugger" replyqueue = ARGV[0] || 'debugger' queuename = '/queue/mcollective.reply.' + replyqueue # Subscribe to the queue connector.connection.subscribe( queuename, {}, "$$".to_i ) # consume all the items in the queue... loop ...