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