Class: MCollective::DDL::AgentDDL

Inherits:
Base
  • Object
show all
Defined in:
lib/mcollective/ddl/agentddl.rb

Overview

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 <[email protected]>",
: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,
       :default     => "fqdn"

 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

Instance Attribute Summary

Attributes inherited from Base

#entities, #meta, #pluginname, #plugintype, #requirements, #usage

Instance Method Summary collapse

Methods inherited from Base

#findddlfile, #help, #loadddlfile, #metadata, #output, #requires, #template_for_plugintype, #validate_input_argument, #validate_requirements

Constructor Details

#initialize(plugin, plugintype = :agent, loadddl = true) ⇒ AgentDDL

Returns a new instance of AgentDDL.



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# File 'lib/mcollective/ddl/agentddl.rb', line 41

def initialize(plugin, plugintype=:agent, loadddl=true)
  @process_aggregate_functions = nil

  super
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(name, *args, &block) ⇒ Object

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



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# File 'lib/mcollective/ddl/agentddl.rb', line 139

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

Instance Method Details

#action(name, input, &block) ⇒ Object

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



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# File 'lib/mcollective/ddl/agentddl.rb', line 116

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) ⇒ Object

Returns the interface for a specific action



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# File 'lib/mcollective/ddl/agentddl.rb', line 202

def action_interface(name)
  @entities[name] || {}
end

#actions ⇒ Object

Returns an array of actions this agent support



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# File 'lib/mcollective/ddl/agentddl.rb', line 207

def actions
  @entities.keys
end

#aggregate(function, format = {:format => nil}) ⇒ Object

Sets the aggregate array for the given action

Raises:



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# File 'lib/mcollective/ddl/agentddl.rb', line 70

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) ⇒ Object

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



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# File 'lib/mcollective/ddl/agentddl.rb', line 85

def display(pref)
  if pref == :flatten
    Log.warn("The display option :flatten is being deprecated and will be removed in the next minor release.")
  end

  # 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) ⇒ Object 



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# File 'lib/mcollective/ddl/agentddl.rb', line 47

def input(argument, properties)
  raise "Input needs a :optional property" unless properties.include?(:optional)

  super
end

#is_function?(method_name) ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/mcollective/ddl/agentddl.rb', line 150

def is_function?(method_name)
  PluginManager.find("aggregate").include?(method_name.to_s)
end

#set_default_input_arguments(action, arguments) ⇒ Object

For a given action and arguments look up the DDL interface to that action and if any arguments in the DDL have a :default value assign that to any input that does not have an argument in the input arguments

This is intended to only be called on clients and not on servers as the clients should never be able to publish non compliant requests and the servers should really not tamper with incoming requests since doing so might raise validation errors that were not raised on the client breaking our fail-fast approach to input validation



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# File 'lib/mcollective/ddl/agentddl.rb', line 163

def set_default_input_arguments(action, arguments)
  input = action_interface(action)[:input]

  return unless input

  input.keys.each do |key|
    if !arguments.include?(key) && !input[key][:default].nil? && !input[key][:optional]
      Log.debug("Setting default value for input '%s' to '%s'" % [key, input[key][:default]])
      arguments[key] = input[key][:default]
    end
  end
end

#summarize(&block) ⇒ Object

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



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# File 'lib/mcollective/ddl/agentddl.rb', line 61

def summarize(&block)
  unless @config.mode == :server
    @process_aggregate_functions = true
    block.call
    @process_aggregate_functions = nil
  end
end

#validate_rpc_request(action, arguments) ⇒ Object

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



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# File 'lib/mcollective/ddl/agentddl.rb', line 178

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