# class MCollective::RPC::Agent

A wrapper around the traditional agent, it takes care of a lot of the tedious setup you would do for each agent allowing you to just create methods following a naming standard leaving the heavy lifting up to this clas.

See marionette-collective.org/simplerpc/agents.html

It only really makes sense to use this with a Simple RPC client on the other end, basic usage would be:

    module MCollective
      module Agent
        class Helloworld<RPC::Agent
          action "hello" do
            reply[:msg] = "Hello #{request[:name]}"
          end

          action "foo" do
            implemented_by "/some/script.sh"
          end
        end
      end
    end

If you wish to implement the logic for an action using an external script use the implemented_by method that will cause your script to be run with 2 arguments.

The first argument is a file containing JSON with the request and the 2nd argument is where the script should save its output as a JSON hash.

We also currently have the validation code in here, this will be moved to plugins soon.

### Attributes

agent_name[RW]
config[R]
ddl[R]
logger[R]
meta[R]
reply[RW]
request[RW]
timeout[R]

### Public Class Methods

actions() click to toggle source

Returns an array of actions this agent support

    # File lib/mcollective/rpc/agent.rb, line 153
    def self.actions
      public_instance_methods.sort.grep(/_action$/).map do |method|
        $1 if method =~ /(.+)_action$/
      end
    end

activate?() click to toggle source

By default RPC Agents support a toggle in the configuration that can enable and disable them based on the agent name

Example an agent called Foo can have:

plugin.foo.activate_agent = false

and this will prevent the agent from loading on this particular machine.

Agents can use the activate_when helper to override this for example:

activate_when do

    File.exist?("/usr/bin/puppet")

end

    # File lib/mcollective/rpc/agent.rb, line 135
    def self.activate?
      agent_name = self.to_s.split("::").last.downcase

      Log.debug("Starting default activation checks for #{agent_name}")

      should_activate = Config.instance.pluginconf["#{agent_name}.activate_agent"]

      if should_activate
        Log.debug("Found plugin config #{agent_name}.activate_agent with value #{should_activate}")
        unless should_activate =~ /^1|y|true$/
          return false
        end
      end

      return true
    end

new() click to toggle source

    # File lib/mcollective/rpc/agent.rb, line 37
    def initialize
      @agent_name = self.class.to_s.split("::").last.downcase

      load_ddl

      @logger = Log.instance
      @config = Config.instance

      # if we have a global authorization provider enable it
      # plugins can still override it per plugin
      self.class.authorized_by(@config.rpcauthprovider) if @config.rpcauthorization

      startup_hook
    end

### Public Instance Methods

handlemsg(msg, connection) click to toggle source

    # File lib/mcollective/rpc/agent.rb, line 62
    def handlemsg(msg, connection)
      @request = RPC::Request.new(msg, @ddl)
      @reply = RPC::Reply.new(@request.action, @ddl)

      begin
        # Incoming requests need to be validated against the DDL thus reusing
        # all the work users put into creating DDLs and creating a consistant
        # quality of input validation everywhere with the a simple once off
        # investment of writing a DDL
        @request.validate!

        # Calls the authorization plugin if any is defined
        # if this raises an exception we wil just skip processing this
        # message
        authorization_hook(@request) if respond_to?("authorization_hook")

        # Audits the request, currently continues processing the message
        # we should make this a configurable so that an audit failure means
        # a message wont be processed by this node depending on config
        audit_request(@request, connection)

        before_processing_hook(msg, connection)

        if respond_to?("#{@request.action}_action")
          send("#{@request.action}_action")
        else
          raise UnknownRPCAction, "Unknown action: #{@request.action}"
        end
      rescue RPCAborted => e
        @reply.fail e.to_s, 1

      rescue UnknownRPCAction => e
        @reply.fail e.to_s, 2

      rescue MissingRPCData => e
        @reply.fail e.to_s, 3

      rescue InvalidRPCData => e
        @reply.fail e.to_s, 4

      rescue UnknownRPCError => e
        @reply.fail e.to_s, 5

      rescue Exception => e
        @reply.fail e.to_s, 5

      end

      after_processing_hook

      if @request.should_respond?
        return @reply.to_hash
      else
        Log.debug("Client did not request a response, surpressing reply")
        return nil
      end
    end

load_ddl() click to toggle source

    # File lib/mcollective/rpc/agent.rb, line 52
    def load_ddl
      @ddl = DDL.new(@agent_name, :agent)
      @meta = @ddl.meta
      @timeout = @meta[:timeout] || 10

    rescue Exception => e
      Log.error("Failed to load DDL for the '%s' agent, DDLs are required: %s: %s" % [@agent_name, e.class, e.to_s])
      raise DDLValidationError
    end