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
30 def self.<<(plugin)
31   plugin[:single_instance] = true unless plugin.include?(:single_instance)
32 
33   type = plugin[:type]
34   klass = plugin[:class]
35   single = plugin[:single_instance]
36 
37   raise("Plugin #{type} already loaded") if @plugins.include?(type)
38 
39 
40   # If we get a string then store 'nil' as the instance, signalling that we'll
41   # create the class later on demand.
42   if klass.is_a?(String)
43     @plugins[type] = {:loadtime => Time.now, :class => klass, :instance => nil, :single => single}
44     Log.debug("Registering plugin #{type} with class #{klass} single_instance: #{single}")
45   else
46     @plugins[type] = {:loadtime => Time.now, :class => klass.class, :instance => klass, :single => true}
47     Log.debug("Registering plugin #{type} with class #{klass.class} single_instance: true")
48   end
49 end
[](plugin) click to toggle source

Gets a plugin by type

   # File lib/mcollective/pluginmanager.rb
72 def self.[](plugin)
73   raise("No plugin #{plugin} defined") unless @plugins.include?(plugin)
74 
75   klass = @plugins[plugin][:class]
76 
77   if @plugins[plugin][:single]
78     # Create an instance of the class if one hasn't been done before
79     if @plugins[plugin][:instance] == nil
80       Log.debug("Returning new plugin #{plugin} with class #{klass}")
81       @plugins[plugin][:instance] = create_instance(klass)
82     else
83       Log.debug("Returning cached plugin #{plugin} with class #{klass}")
84     end
85 
86     @plugins[plugin][:instance]
87   else
88     Log.debug("Returning new plugin #{plugin} with class #{klass}")
89     create_instance(klass)
90   end
91 end
clear() click to toggle source

deletes all registered plugins

   # File lib/mcollective/pluginmanager.rb
67 def self.clear
68   @plugins.clear
69 end
create_instance(klass) click to toggle source

use eval to create an instance of a class

    # File lib/mcollective/pluginmanager.rb
 94 def self.create_instance(klass)
 95   begin
 96     eval("#{klass}.new")
 97   rescue Exception => e
 98     raise("Could not create instance of plugin #{klass}: #{e}")
 99   end
100 end
delete(plugin) click to toggle source

Removes a plugim the list

   # File lib/mcollective/pluginmanager.rb
52 def self.delete(plugin)
53   @plugins.delete(plugin) if @plugins.include?(plugin)
54 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
116 def self.find(type, extension="rb")
117   extension = ".#{extension}" unless extension.match(/^\./)
118 
119   plugins = []
120 
121   Config.instance.libdir.each do |libdir|
122     plugdir = File.join([libdir, "mcollective", type.to_s])
123     next unless File.directory?(plugdir)
124 
125     Dir.new(plugdir).grep(/#{extension}$/).map do |plugin|
126       plugins << File.basename(plugin, extension)
127     end
128   end
129 
130   plugins.sort.uniq
131 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
148 def self.find_and_load(type, extension="rb")
149   extension = ".#{extension}" unless extension.match(/^\./)
150 
151   klasses = find(type, extension).map do |plugin|
152     if block_given?
153       next unless yield(plugin)
154     end
155 
156     "%s::%s::%s" % [ "MCollective", type.capitalize, plugin.capitalize ]
157   end.compact
158 
159   klasses.sort.uniq.each {|klass| loadclass(klass, true)}
160 end
grep(regex) click to toggle source

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

    # File lib/mcollective/pluginmanager.rb
176 def self.grep(regex)
177   @plugins.keys.grep(regex)
178 end
include?(plugin) click to toggle source

Finds out if we have a plugin with the given name

   # File lib/mcollective/pluginmanager.rb
57 def self.include?(plugin)
58   @plugins.include?(plugin)
59 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
164 def self.loadclass(klass, squash_failures=false)
165   fname = klass.gsub("::", "/").downcase + ".rb"
166 
167   Log.debug("Loading #{klass} from #{fname}")
168 
169   load fname
170 rescue Exception => e
171   Log.error("Failed to load #{klass}: #{e}")
172   raise unless squash_failures
173 end
pluginlist() click to toggle source

Provides a list of plugins we know about

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