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, :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
# File lib/mcollective/ddl/agentddl.rb, line 41 def initialize(plugin, plugintype=:agent, loadddl=true) @process_aggregate_functions = nil super end
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 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
Returns the interface for a specific action
# File lib/mcollective/ddl/agentddl.rb, line 202 def action_interface(name) @entities[name] || {} end
Returns an array of actions this agent support
# File lib/mcollective/ddl/agentddl.rb, line 207 def actions @entities.keys end
Sets the aggregate array for the given action
# 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
Sets the display preference to either :ok, :failed, :flatten or :always operates on action level
# 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
# File lib/mcollective/ddl/agentddl.rb, line 47 def input(argument, properties) raise "Input needs a :optional property" unless properties.include?(:optional) super end
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 150 def is_function?(method_name) PluginManager.find("aggregate").include?(method_name.to_s) end
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 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
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, 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
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 61 def summarize(&block) unless @config.mode == :server @process_aggregate_functions = true block.call @process_aggregate_functions = nil end end
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 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