Class: MCollective::Agents

Inherits:
Object
  • Object
show all
Defined in:
lib/mcollective/agents.rb

Overview

A collection of agents, loads them, reloads them and dispatches messages to them. It uses the PluginManager to store, load and manage instances of plugins.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(agents = {}) ⇒ Agents

Returns a new instance of Agents.



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# File 'lib/mcollective/agents.rb', line 5

def initialize(agents={})
  @config = Config.instance
  raise "Configuration has not been loaded, can't load agents" unless @config.configured

  @@agents = agents # rubocop:disable Style/ClassVars

  loadagents
end

Class Method Details

.agentlist ⇒ Object

Get a list of agents that we have



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# File 'lib/mcollective/agents.rb', line 145

def self.agentlist
  @@agents.keys
end

Instance Method Details

#activate_agent?(agent) ⇒ Boolean

Checks if a plugin should be activated by calling #activate? on it if it responds to that method else always activate it

Returns:

  • (Boolean) 


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# File 'lib/mcollective/agents.rb', line 87

def activate_agent?(agent)
  klass = Kernel.const_get("MCollective").const_get("Agent").const_get(agent.capitalize)

  if klass.respond_to?("activate?")
    klass.activate?
  else
    Log.debug("#{klass} does not have an activate? method, activating as default")
    true
  end
rescue Exception # rubocop:disable Lint/RescueException
  Log.warn("Agent activation check for %s #{agent} failed: %s: %s" % [agent, $!.class, $!])
  false
end

#class_for_agent(agent) ⇒ Object

Builds a class name string given a Agent name



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# File 'lib/mcollective/agents.rb', line 80

def class_for_agent(agent)
  "MCollective::Agent::#{agent.capitalize}"
end

#clear! ⇒ Object

Deletes all agents



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# File 'lib/mcollective/agents.rb', line 15

def clear!
  @@agents.each_key do |agent|
    PluginManager.delete "#{agent}_agent"
    Util.unsubscribe(Util.make_subscriptions(agent, :broadcast))
  end

  @@agents = {} # rubocop:disable Style/ClassVars
end

#dispatch(request, connection) ⇒ Object

Dispatches a message to an agent, accepts a block that will get run if there are any replies to process from the agent



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# File 'lib/mcollective/agents.rb', line 120

def dispatch(request, connection)
  Log.debug("Dispatching a message to agent #{request.agent}")

  Thread.new do
    begin
      agent = PluginManager["#{request.agent}_agent"]

      Timeout.timeout(agent.timeout) do
        replies = agent.handlemsg(request.payload, connection)

        # Agents can decide if they wish to reply or not,
        # returning nil will mean nothing goes back to the
        # requestor
        yield(replies) unless replies.nil?
      end
    rescue Timeout::Error
      Log.warn("Timeout while handling message for %s" % request.agent)
    rescue Exception # rubocop:disable Lint/RescueException
      Log.error("Execution of %s failed: %s" % [request.agent, $!])
      Log.error(e.backtrace.join("\n\t\t"))
    end
  end
end

#findagentfile(agentname) ⇒ Object

searches the libdirs for agents



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# File 'lib/mcollective/agents.rb', line 102

def findagentfile(agentname)
  @config.libdir.each do |libdir|
    agentfile = File.join([libdir, "mcollective", "agent", "#{agentname}.rb"])
    if File.exist?(agentfile)
      Log.debug("Found #{agentname} at #{agentfile}")
      return agentfile
    end
  end
  false
end

#include?(agentname) ⇒ Boolean

Determines if we have an agent with a certain name

Returns:

  • (Boolean) 


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# File 'lib/mcollective/agents.rb', line 114

def include?(agentname)
  PluginManager.include?("#{agentname}_agent")
end

#loadagent(agentname) ⇒ Object

Loads a specified agent from disk if available



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# File 'lib/mcollective/agents.rb', line 42

def loadagent(agentname)
  agentfile = findagentfile(agentname)
  return false unless agentfile

  classname = class_for_agent(agentname)

  PluginManager.delete("#{agentname}_agent")

  begin
    single_instance = ["registration", "discovery"].include?(agentname)

    PluginManager.loadclass(classname)

    if activate_agent?(agentname)
      PluginManager << {:type => "#{agentname}_agent", :class => classname, :single_instance => single_instance}

      # Attempt to instantiate the agent once so any validation and hooks get run
      # this does a basic sanity check on the agent as a whole, if this fails it
      # will be removed from the plugin list
      PluginManager["#{agentname}_agent"]

      Util.subscribe(Util.make_subscriptions(agentname, :broadcast)) unless @@agents.include?(agentname)

      @@agents[agentname] = {:file => agentfile}
      true
    else
      Log.debug("Not activating agent #{agentname} due to agent policy in activate? method")
      false
    end
  rescue Exception # rubocop:disable Lint/RescueException
    Log.error("Loading agent %s failed: %s" % [agentname, $!])
    PluginManager.delete("%s_agent" % agentname)

    false
  end
end

#loadagents ⇒ Object

Loads all agents from disk



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# File 'lib/mcollective/agents.rb', line 25

def loadagents
  Log.debug("Reloading all agents from disk")

  clear!

  @config.libdir.each do |libdir|
    agentdir = "#{libdir}/mcollective/agent"
    next unless File.directory?(agentdir)

    Dir.new(agentdir).grep(/\.rb$/).each do |agent|
      agentname = File.basename(agent, ".rb")
      loadagent(agentname) unless PluginManager.include?("#{agentname}_agent")
    end
  end
end