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         => "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

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.



41
42
43
44
45
 
# 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



139
140
141
142
143
144
145
 
# 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



116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
 
# 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



243
244
245
 
# File 'lib/mcollective/ddl/agentddl.rb', line 243

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

#actions ⇒ Object

Returns an array of actions this agent support



248
249
250
 
# File 'lib/mcollective/ddl/agentddl.rb', line 248

def actions
  @entities.keys
end

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

Sets the aggregate array for the given action

Raises:



70
71
72
73
74
75
76
77
78
79
80
81
 
# 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



85
86
87
88
89
90
91
92
93
94
95
96
97
 
# 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 



47
48
49
50
51
 
# 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) 


150
151
152
 
# 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



163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
 
# 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 key.is_a?(Symbol) && arguments.include?(key.to_s) && !input.include?(key.to_s)
      compat_arg = key.to_s
    else
      compat_arg = key
    end

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



61
62
63
64
65
66
67
 
# 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

#symbolize_basic_input_arguments(input, arguments) ⇒ Object

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



199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
 
# File 'lib/mcollective/ddl/agentddl.rb', line 199

def symbolize_basic_input_arguments(input, arguments)
  warned = false

  Hash[arguments.map do |key, value|
    if input.include?(key.intern) && input.include?(key.to_s) && !warned
      Log.warn("String and Symbol versions of input %s found in the DDL for %s, ensure your DDL keys are unique." % [key, @pluginname])
      warned = true
    end

    if key.is_a?(String) && input.include?(key.intern) && !input.include?(key)
      [key.intern, value]
    else
      [key, value]
    end
  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.



218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
 
# File 'lib/mcollective/ddl/agentddl.rb', line 218

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] || {}
  compatible_args = symbolize_basic_input_arguments(input, arguments)

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

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

  true
end