class 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         => "https://docs.puppetlabs.com/mcollective/",
: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

Public Class Methods

new(plugin, plugintype=:agent, loadddl=true) click to toggle source
Calls superclass method
   # File lib/mcollective/ddl/agentddl.rb
41 def initialize(plugin, plugintype=:agent, loadddl=true)
42   @process_aggregate_functions = nil
43 
44   super
45 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
116 def action(name, input, &block)
117   raise "Action needs a :description property" unless input.include?(:description)
118 
119   unless @entities.include?(name)
120     @entities[name] = {}
121     @entities[name][:action] = name
122     @entities[name][:input] = {}
123     @entities[name][:output] = {}
124     @entities[name][:display] = :failed
125     @entities[name][:description] = input[:description]
126   end
127 
128   # if a block is passed it might be creating input methods, call it
129   # we set @current_entity so the input block can know what its talking
130   # to, this is probably an epic hack, need to improve.
131   @current_entity = name
132   block.call if block_given?
133   @current_entity = nil
134 end
action_interface(name) click to toggle source

Returns the interface for a specific action

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

Returns an array of actions this agent support

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

Sets the aggregate array for the given action

   # File lib/mcollective/ddl/agentddl.rb
70 def aggregate(function, format = {:format => nil})
71   raise(DDLValidationError, "Formats supplied to aggregation functions should be a hash") unless format.is_a?(Hash)
72   raise(DDLValidationError, "Formats supplied to aggregation functions must have a :format key") unless format.keys.include?(:format)
73   raise(DDLValidationError, "Functions supplied to aggregate should be a hash") unless function.is_a?(Hash)
74 
75   unless (function.keys.include?(:args)) && function[:args]
76     raise DDLValidationError, "aggregate method for action '%s' missing a function parameter" % entities[@current_entity][:action]
77   end
78 
79   entities[@current_entity][:aggregate] ||= []
80   entities[@current_entity][:aggregate] << (format[:format].nil? ? function : function.merge(format))
81 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
85 def display(pref)
86   if pref == :flatten
87     Log.warn("The display option :flatten is being deprecated and will be removed in the next minor release.")
88   end
89 
90   # defaults to old behavior, complain if its supplied and invalid
91   unless [:ok, :failed, :flatten, :always].include?(pref)
92     raise "Display preference #{pref} is not valid, should be :ok, :failed, :flatten or :always"
93   end
94 
95   action = @current_entity
96   @entities[action][:display] = pref
97 end
input(argument, properties) click to toggle source
Calls superclass method
   # File lib/mcollective/ddl/agentddl.rb
47 def input(argument, properties)
48   raise "Input needs a :optional property" unless properties.include?(:optional)
49 
50   super
51 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
150 def is_function?(method_name)
151   PluginManager.find("aggregate").include?(method_name.to_s)
152 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
139 def method_missing(name, *args, &block)
140   unless @process_aggregate_functions || is_function?(name)
141     raise NoMethodError, "undefined local variable or method `#{name}'", caller
142   end
143 
144   return {:function => name, :args => args}
145 end
set_default_input_arguments(action, arguments) click to toggle source

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

    # File lib/mcollective/ddl/agentddl.rb
163 def set_default_input_arguments(action, arguments)
164   input = action_interface(action)[:input]
165 
166   return unless input
167 
168   input.keys.each do |key|
169     if key.is_a?(Symbol) && arguments.include?(key.to_s) && !input.include?(key.to_s)
170       compat_arg = key.to_s
171     else
172       compat_arg = key
173     end
174 
175     if !arguments.include?(compat_arg) && !input[key][:default].nil? && !input[key][:optional]
176       Log.debug("Setting default value for input '%s' to '%s'" % [key, input[key][:default]])
177       arguments[compat_arg] = input[key][:default]
178     end
179   end
180 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
61 def summarize(&block)
62   unless @config.mode == :server
63     @process_aggregate_functions = true
64     block.call
65     @process_aggregate_functions = nil
66   end
67 end
symbolize_basic_input_arguments(input, arguments) click to toggle source

Creates a new set of arguments with string arguments mapped to symbol ones

This is to assist with moving to a JSON pure world where requests might come in from REST or other languages, those languages and indeed JSON itself does not support symbols.

It ensures a backward compatible mode where for rpcutil both of these requests are equivelant

c.get_fact(:fact => "cluster")
c.get_fact("fact" => "cluster")

The case where both :fact and “fact” is in the DDL cannot be handled correctly and this code will assume the caller means “fact” in that case. There's no way to represent such a request in JSON and just in general sounds like a bad idea, so a warning is logged which would in default client configuration appear on the clients display

    # File lib/mcollective/ddl/agentddl.rb
199 def symbolize_basic_input_arguments(input, arguments)
200   warned = false
201 
202   Hash[arguments.map do |key, value|
203     if input.include?(key.intern) && input.include?(key.to_s) && !warned
204       Log.warn("String and Symbol versions of input %s found in the DDL for %s, ensure your DDL keys are unique." % [key, @pluginname])
205       warned = true
206     end
207 
208     if key.is_a?(String) && input.include?(key.intern) && !input.include?(key)
209       [key.intern, value]
210     else
211       [key, value]
212     end
213   end]
214 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
218 def validate_rpc_request(action, arguments)
219   # is the action known?
220   unless actions.include?(action)
221     raise DDLValidationError, "Attempted to call action #{action} for #{@pluginname} but it's not declared in the DDL"
222   end
223 
224   input = action_interface(action)[:input] || {}
225   compatible_args = symbolize_basic_input_arguments(input, arguments)
226 
227   input.keys.each do |key|
228     unless input[key][:optional]
229       unless compatible_args.include?(key)
230         raise DDLValidationError, "Action #{action} needs a #{key} argument"
231       end
232     end
233 
234     if compatible_args.include?(key)
235       validate_input_argument(input, key, compatible_args[key])
236     end
237   end
238 
239   true
240 end