# module MCollective::PluginManager

A simple plugin manager, it stores one plugin each of a specific type the idea is that we can only have one security provider, one connector etc.

### Public Class Methods

<<(plugin) click to toggle source

Adds a plugin to the list of plugins, we expect a hash like:

    {:type => "base",
     :class => foo.new}

or like:

    {:type => "base",
     :class => "Foo::Bar"}

In the event that we already have a class with the given type an exception will be raised.

If the :class passed is a String then we will delay instantiation till the first time someone asks for the plugin, this is because most likely the registration gets done by inherited() hooks, at which point the plugin class is not final.

If we were to do a .new here the Class initialize method would get called and not the plugins, we there for only initialize the classes when they get requested via []

By default all plugin instances are cached and returned later so there’s always a single instance. You can pass :single_instance => false when calling this to instruct it to always return a new instance when a copy is requested. This only works with sending a String for :class.

    # File lib/mcollective/pluginmanager.rb, line 30
    def self.<<(plugin)
      plugin[:single_instance] = true unless plugin.include?(:single_instance)

      type = plugin[:type]
      klass = plugin[:class]
      single = plugin[:single_instance]

      raise("Plugin #{type} already loaded") if @plugins.include?(type)

      # If we get a string then store 'nil' as the instance, signalling that we'll
      # create the class later on demand.
      if klass.is_a?(String)
        @plugins[type] = {:loadtime => Time.now, :class => klass, :instance => nil, :single => single}
        Log.debug("Registering plugin #{type} with class #{klass} single_instance: #{single}")
      else
        @plugins[type] = {:loadtime => Time.now, :class => klass.class, :instance => klass, :single => true}
        Log.debug("Registering plugin #{type} with class #{klass.class} single_instance: true")
      end
    end

[](plugin) click to toggle source

Gets a plugin by type

    # File lib/mcollective/pluginmanager.rb, line 72
    def self.[](plugin)
      raise("No plugin #{plugin} defined") unless @plugins.include?(plugin)

      klass = @plugins[plugin][:class]

      if @plugins[plugin][:single]
        # Create an instance of the class if one hasn't been done before
        if @plugins[plugin][:instance] == nil
          Log.debug("Returning new plugin #{plugin} with class #{klass}")
          @plugins[plugin][:instance] = create_instance(klass)
        else
          Log.debug("Returning cached plugin #{plugin} with class #{klass}")
        end

        @plugins[plugin][:instance]
      else
        Log.debug("Returning new plugin #{plugin} with class #{klass}")
        create_instance(klass)
      end
    end

clear() click to toggle source

deletes all registered plugins

    # File lib/mcollective/pluginmanager.rb, line 67
    def self.clear
      @plugins.clear
    end

create_instance(klass) click to toggle source

use eval to create an instance of a class

    # File lib/mcollective/pluginmanager.rb, line 94
    def self.create_instance(klass)
      begin
        eval("#{klass}.new")
      rescue Exception => e
        raise("Could not create instance of plugin #{klass}: #{e}")
      end
    end

delete(plugin) click to toggle source

Removes a plugim the list

    # File lib/mcollective/pluginmanager.rb, line 52
    def self.delete(plugin)
      @plugins.delete(plugin) if @plugins.include?(plugin)
    end

find(type, extension="rb") click to toggle source

Finds plugins in all configured libdirs

    find("agent")

will return an array of just agent names, for example:

    ["puppetd", "package"]

Can also be used to find files of other extensions:

    find("agent", "ddl")

Will return the same list but only of files with extension .ddl in the agent subdirectory

    # File lib/mcollective/pluginmanager.rb, line 116
    def self.find(type, extension="rb")
      extension = ".#{extension}" unless extension.match(/^\./)

      plugins = []

      Config.instance.libdir.each do |libdir|
        plugdir = File.join([libdir, "mcollective", type.to_s])
        next unless File.directory?(plugdir)

        Dir.new(plugdir).grep(/#{extension}$/).map do |plugin|
          plugins << File.basename(plugin, extension)
        end
      end

      plugins.sort.uniq
    end

find_and_load(type, extension="rb") { |plugin| ... } click to toggle source

Finds and loads from disk all plugins from all libdirs that match certain criteria.

    find_and_load("pluginpackager")

Will find all .rb files in the libdir/mcollective/pluginpackager/ directory in all libdirs and load them from disk.

You can influence what plugins get loaded using a block notation:

    find_and_load("pluginpackager") do |plugin|
       plugin.match(/puppet/)
    end

This will load only plugins matching /puppet/

    # File lib/mcollective/pluginmanager.rb, line 148
    def self.find_and_load(type, extension="rb")
      extension = ".#{extension}" unless extension.match(/^\./)

      klasses = find(type, extension).map do |plugin|
        if block_given?
          next unless yield(plugin)
        end

        "%s::%s::%s" % [ "MCollective", type.capitalize, plugin.capitalize ]
      end.compact

      klasses.sort.uniq.each {|klass| loadclass(klass, true)}
    end

grep(regex) click to toggle source

Grep’s over the plugin list and returns the list found

    # File lib/mcollective/pluginmanager.rb, line 176
    def self.grep(regex)
      @plugins.keys.grep(regex)
    end

include?(plugin) click to toggle source

Finds out if we have a plugin with the given name

    # File lib/mcollective/pluginmanager.rb, line 57
    def self.include?(plugin)
      @plugins.include?(plugin)
    end

loadclass(klass, squash_failures=false) click to toggle source

Loads a class from file by doing some simple search/replace on class names and then doing a require.

    # File lib/mcollective/pluginmanager.rb, line 164
    def self.loadclass(klass, squash_failures=false)
      fname = klass.gsub("::", "/").downcase + ".rb"

      Log.debug("Loading #{klass} from #{fname}")

      load fname
    rescue Exception => e
      Log.error("Failed to load #{klass}: #{e}")
      raise unless squash_failures
    end

pluginlist() click to toggle source

Provides a list of plugins we know about

    # File lib/mcollective/pluginmanager.rb, line 62
    def self.pluginlist
      @plugins.keys.sort
    end