Learning MCollective

Chapter 5. Agent and Client Plugins

The software installed on the nodes you control through MCollective is a daemon called mcollectived. We will install several agents in this chapter to provide powerful new features. mcollectived is called a server because it functions as an application server. Its abilities are expanded by installing agent plugins to extend and enhance what we can control on the node.

Each agent has a matching client or application that knows how to issue requests specific to that agent. We’ll install and use the client applications to communicate with the agent.

Connector Plugins

On each node in your environment, we have installed the mcollectived service. For this daemon to operate correctly, it requires two plugins:

• A connector plugin to establish a link with the middleware and subscribe to topics

• A security plugin to encrypt and decrypt the communications

These two connectors must be the same throughout your environment. In most situations, the configuration for these plugins will be the same for every server.

For the baseline setup described in Chapter 2, we used:

connector = activemq

The alternative would have been to use RabbitMQ or to build a custom middleware connector.

securityprovider = psk

We will discuss alternative security plugins like SSL in Chapter 13.

Installing Agents from Packages

Puppet Labs provides a number of MCollective agents that know how to do common systems-management tasks (e.g., query, start, and stop processes, ...