Module: MCollective::PluginManager

Defined in:
lib/mcollective/pluginmanager.rb

Overview

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.

Class Method Summary collapse

Class Method Details

.<<(plugin) ⇒ Object

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.



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# 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) ⇒ Object

Gets a plugin by type



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# 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 ⇒ Object

deletes all registered plugins



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# File 'lib/mcollective/pluginmanager.rb', line 67

def self.clear
  @plugins.clear
end

.create_instance(klass) ⇒ Object

use eval to create an instance of a class



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# 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) ⇒ Object

Removes a plugim the list



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# File 'lib/mcollective/pluginmanager.rb', line 52

def self.delete(plugin)
  @plugins.delete(plugin) if @plugins.include?(plugin)
end

.find(type, extension = "rb") ⇒ Object

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



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# 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") ⇒ Object

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/



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# 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) ⇒ Object

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



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# File 'lib/mcollective/pluginmanager.rb', line 176

def self.grep(regex)
  @plugins.keys.grep(regex)
end

.include?(plugin) ⇒ Boolean

Finds out if we have a plugin with the given name

Returns:

  • (Boolean) 


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# File 'lib/mcollective/pluginmanager.rb', line 57

def self.include?(plugin)
  @plugins.include?(plugin)
end

.loadclass(klass, squash_failures = false) ⇒ Object

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



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# 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 ⇒ Object

Provides a list of plugins we know about



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# File 'lib/mcollective/pluginmanager.rb', line 62

def self.pluginlist
  @plugins.keys.sort
end