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MCollective::DDL::AgentDDL

A DDL class specific to agent plugins.

A full DDL can be seen below with all the possible bells and whistles present.

metadata :name => “Utilities and Helpers for SimpleRPC Agents”,

:description => "General helpful actions that expose stats and internals to SimpleRPC clients",
:author      => "R.I.Pienaar <rip@devco.net>",
:license     => "Apache License, Version 2.0",
:version     => "1.0",
:url         => "http://marionette-collective.org/",
:timeout     => 10

action “get_fact”, :description => “Retrieve a single fact from the fact store” do

 display :always

 input :fact,
       :prompt      => "The name of the fact",
       :description => "The fact to retrieve",
       :type        => :string,
       :validation  => '^[\w\-\.]+$',
       :optional    => false,
       :maxlength   => 40

 output :fact,
        :description => "The name of the fact being returned",
        :display_as  => "Fact"

 output :value,
        :description => "The value of the fact",
        :display_as  => "Value",
        :default     => ""

summarize do
    aggregate summary(:value)
end

end

Public Class Methods

new(plugin, plugintype=:agent, loadddl=true) click to toggle source
# File lib/mcollective/ddl/agentddl.rb, line 40
def initialize(plugin, plugintype=:agent, loadddl=true)
  @process_aggregate_functions = nil

  super
end

Public Instance Methods

action(name, input, &block) click to toggle source

Creates the definition for an action, you can nest input definitions inside the action to attach inputs and validation to the actions

action "status", :description => "Restarts a Service" do
   display :always

   input  "service",
          :prompt      => "Service Action",
          :description => "The action to perform",
          :type        => :list,
          :optional    => true,
          :list        => ["start", "stop", "restart", "status"]

   output "status",
          :description => "The status of the service after the action"

end
# File lib/mcollective/ddl/agentddl.rb, line 111
def action(name, input, &block)
  raise "Action needs a :description property" unless input.include?(:description)

  unless @entities.include?(name)
    @entities[name] = {}
    @entities[name][:action] = name
    @entities[name][:input] = {}
    @entities[name][:output] = {}
    @entities[name][:display] = :failed
    @entities[name][:description] = input[:description]
  end

  # if a block is passed it might be creating input methods, call it
  # we set @current_entity so the input block can know what its talking
  # to, this is probably an epic hack, need to improve.
  @current_entity = name
  block.call if block_given?
  @current_entity = nil
end
action_interface(name) click to toggle source

Returns the interface for a specific action

# File lib/mcollective/ddl/agentddl.rb, line 175
def action_interface(name)
  @entities[name] || {}
end
actions() click to toggle source

Returns an array of actions this agent support

# File lib/mcollective/ddl/agentddl.rb, line 180
def actions
  @entities.keys
end
aggregate(function, format = {:format => nil}) click to toggle source

Sets the aggregate array for the given action

# File lib/mcollective/ddl/agentddl.rb, line 69
def aggregate(function, format = {:format => nil})
  raise(DDLValidationError, "Formats supplied to aggregation functions should be a hash") unless format.is_a?(Hash)
  raise(DDLValidationError, "Formats supplied to aggregation functions must have a :format key") unless format.keys.include?(:format)
  raise(DDLValidationError, "Functions supplied to aggregate should be a hash") unless function.is_a?(Hash)

  unless (function.keys.include?(:args)) && function[:args]
    raise DDLValidationError, "aggregate method for action '%s' missing a function parameter" % entities[@current_entity][:action]
  end

  entities[@current_entity][:aggregate] ||= []
  entities[@current_entity][:aggregate] << (format[:format].nil? ? function : function.merge(format))
end
display(pref) click to toggle source

Sets the display preference to either :ok, :failed, :flatten or :always operates on action level

# File lib/mcollective/ddl/agentddl.rb, line 84
def display(pref)
  # defaults to old behavior, complain if its supplied and invalid
  unless [:ok, :failed, :flatten, :always].include?(pref)
    raise "Display preference #{pref} is not valid, should be :ok, :failed, :flatten or :always"
  end

  action = @current_entity
  @entities[action][:display] = pref
end
input(argument, properties) click to toggle source
# File lib/mcollective/ddl/agentddl.rb, line 46
def input(argument, properties)
  raise "Input needs a :optional property" unless properties.include?(:optional)

  super
end
is_function?(method_name) click to toggle source

Checks if a method name matches a aggregate plugin. This is used by method missing so that we dont greedily assume that every method_missing call in an agent ddl has hit a aggregate function.

# File lib/mcollective/ddl/agentddl.rb, line 145
def is_function?(method_name)
  PluginManager.find("aggregate").include?(method_name.to_s)
end
method_missing(name, *args, &block) click to toggle source

If the method name matches a # aggregate function, we return the function with args as a hash. This will only be active if the @process_aggregate_functions is set to true which only happens in the summarize block

# File lib/mcollective/ddl/agentddl.rb, line 134
def method_missing(name, *args, &block)
  unless @process_aggregate_functions || is_function?(name)
    raise NoMethodError, "undefined local variable or method `#{name}'", caller
  end

  return {:function => name, :args => args}
end
summarize(&block) click to toggle source

Calls the summarize block defined in the ddl. Block will not be called if the ddl is getting processed on the server side. This means that aggregate plugins only have to be present on the client side.

The @process_aggregate_functions variable is used by the method_missing block to determine if it should kick in, this way we very tightly control where we activate the method_missing behavior turning it into a noop otherwise to maximise the chance of providing good user feedback

# File lib/mcollective/ddl/agentddl.rb, line 60
def summarize(&block)
  unless @config.mode == :server
    @process_aggregate_functions = true
    block.call
    @process_aggregate_functions = nil
  end
end
validate_rpc_request(action, arguments) click to toggle source

Helper to use the DDL to figure out if the remote call to an agent should be allowed based on action name and inputs.

# File lib/mcollective/ddl/agentddl.rb, line 151
def validate_rpc_request(action, arguments)
  # is the action known?
  unless actions.include?(action)
    raise DDLValidationError, "Attempted to call action #{action} for #{@pluginname} but it's not declared in the DDL"
  end

  input = action_interface(action)[:input] || {}

  input.keys.each do |key|
    unless input[key][:optional]
      unless arguments.keys.include?(key)
        raise DDLValidationError, "Action #{action} needs a #{key} argument"
      end
    end

    if arguments.keys.include?(key)
      validate_input_argument(input, key, arguments[key])
    end
  end

  true
end

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