Class | MCollective::RPC::DDL |
In: |
lib/mcollective/rpc/ddl.rb
|
Parent: | Object |
A class that helps creating data description language files for agents. You can define meta data, actions, input and output describing the behavior of your agent.
Later you can access this information to assist with creating of user interfaces or online help
A sample DDL can be seen below, you‘d put this in your agent dir as <agent name>.ddl
metadata :name => "SimpleRPC Service Agent", :description => "Agent to manage services using the Puppet service provider", :author => "R.I.Pienaar", :license => "GPLv2", :version => "1.1", :url => "http://mcollective-plugins.googlecode.com/", :timeout => 60 action "status", :description => "Gets the status of a service" do display :always input "service", :prompt => "Service Name", :description => "The service to get the status for", :type => :string, :validation => '^[a-zA-Z\-_\d]+$', :optional => true, :maxlength => 30 output "status", :description => "The status of service", :display_as => "Service Status" end
meta | [R] |
# File lib/mcollective/rpc/ddl.rb, line 39 39: def initialize(agent) 40: @actions = {} 41: @meta = {} 42: @config = MCollective::Config.instance 43: @agent = agent 44: 45: agentdir = "#{@config.libdir}/mcollective/agent" 46: 47: if File.exist?("#{agentdir}/#{agent}.ddl") 48: instance_eval(File.read("#{agentdir}/#{agent}.ddl")) 49: else 50: raise("Can't find DDL for agent '#{agent}' in #{agentdir}/#{agent}.ddl") 51: end 52: 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/rpc/ddl.rb, line 80 80: def action(name, input, &block) 81: raise "Action needs a :description" unless input.include?(:description) 82: 83: unless @actions.include?(name) 84: @actions[name] = {} 85: @actions[name][:action] = name 86: @actions[name][:input] = {} 87: @actions[name][:output] = {} 88: @actions[name][:display] = :failed 89: @actions[name][:description] = input[:description] 90: end 91: 92: # if a block is passed it might be creating input methods, call it 93: # we set @current_action so the input block can know what its talking 94: # to, this is probably an epic hack, need to improve. 95: @current_action = name 96: block.call if block_given? 97: @current_action = nil 98: end
Sets the display preference to either :ok, :failed, :flatten or :always operates on action level
# File lib/mcollective/rpc/ddl.rb, line 148 148: def display(pref) 149: # defaults to old behavior, complain if its supplied and invalid 150: unless [:ok, :failed, :always].include?(pref) 151: raise "Display preference #{pref} :ok, :failed, :flatten or :always" 152: end 153: 154: action = @current_action 155: @actions[action][:display] = pref 156: end
Generates help using the template based on the data created with metadata and input
# File lib/mcollective/rpc/ddl.rb, line 160 160: def help(template) 161: template = IO.readlines(template).join 162: meta = @meta 163: actions = @actions 164: 165: erb = ERB.new(template, 0, '%') 166: erb.result(binding) 167: end
Registers an input argument for a given action
See the documentation for action for how to use this
# File lib/mcollective/rpc/ddl.rb, line 103 103: def input(argument, properties) 104: raise "Cannot figure out what action input #{argument} belongs to" unless @current_action 105: 106: action = @current_action 107: 108: [:prompt, :description, :type, :optional].each do |arg| 109: raise "Input needs a :#{arg}" unless properties.include?(arg) 110: end 111: 112: @actions[action][:input][argument] = {:prompt => properties[:prompt], 113: :description => properties[:description], 114: :type => properties[:type], 115: :optional => properties[:optional]} 116: 117: case properties[:type] 118: when :string 119: raise "Input type :string needs a :validation" unless properties.include?(:validation) 120: raise "String inputs need a :maxlength" unless properties.include?(:validation) 121: 122: @actions[action][:input][argument][:validation] = properties[:validation] 123: @actions[action][:input][argument][:maxlength] = properties[:maxlength] 124: 125: when :list 126: raise "Input type :list needs a :list argument" unless properties.include?(:list) 127: 128: @actions[action][:input][argument][:list] = properties[:list] 129: end 130: end
Registers meta data for the introspection hash
# File lib/mcollective/rpc/ddl.rb, line 55 55: def metadata(meta) 56: [:name, :description, :author, :license, :version, :url, :timeout].each do |arg| 57: raise "Metadata needs a :#{arg}" unless meta.include?(arg) 58: end 59: 60: @meta = meta 61: end
Registers an output argument for a given action
See the documentation for action for how to use this
# File lib/mcollective/rpc/ddl.rb, line 135 135: def output(argument, properties) 136: raise "Cannot figure out what action input #{argument} belongs to" unless @current_action 137: raise "Output #{argument} needs a description" unless properties.include?(:description) 138: raise "Output #{argument} needs a description" unless properties.include?(:display_as) 139: 140: action = @current_action 141: 142: @actions[action][:output][argument] = {:description => properties[:description], 143: :display_as => properties[:display_as]} 144: end
Helper to use the DDL to figure out if the remote call should be allowed based on action name and inputs.
# File lib/mcollective/rpc/ddl.rb, line 181 181: def validate_request(action, arguments) 182: # is the action known? 183: unless actions.include?(action) 184: raise DDLValidationError, "Attempted to call action #{action} for #{@agent} but it's not declared in the DDL" 185: end 186: 187: input = action_interface(action)[:input] 188: 189: input.keys.each do |key| 190: unless input[key][:optional] 191: unless arguments.keys.include?(key) 192: raise DDLValidationError, "Action #{action} needs a #{key} argument" 193: end 194: end 195: 196: # validate strings, lists and booleans, we'll add more types of validators when 197: # all the use cases are clear 198: # 199: # only does validation for arguments actually given, since some might 200: # be optional. We validate the presense of the argument earlier so 201: # this is a safe assumption, just to skip them. 202: # 203: # :string can have maxlength and regex. A maxlength of 0 will bypasss checks 204: # :list has a array of valid values 205: if arguments.keys.include?(key) 206: case input[key][:type] 207: when :string 208: raise DDLValidationError, "Input #{key} should be a string" unless arguments[key].is_a?(String) 209: 210: if input[key][:maxlength].to_i > 0 211: if arguments[key].size > input[key][:maxlength].to_i 212: raise DDLValidationError, "Input #{key} is longer than #{input[key][:maxlength]}" 213: end 214: end 215: 216: unless arguments[key].match(Regexp.new(input[key][:validation])) 217: raise DDLValidationError, "Input #{key} does not match validation regex #{input[key][:validation]}" 218: end 219: 220: when :list 221: unless input[key][:list].include?(arguments[key]) 222: raise DDLValidationError, "Input #{key} doesn't match list #{input[key][:list].join(', ')}" 223: end 224: 225: when :boolean 226: unless [TrueClass, FalseClass].include?(arguments[key].class) 227: raise DDLValidationError, "Input #{key} should be a boolean" 228: end 229: end 230: end 231: end 232: end