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: if ddlfile = findddlfile(agent) 46: instance_eval(File.read(ddlfile)) 47: else 48: raise("Can't find DDL for agent '#{agent}'") 49: end 50: 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 89 89: def action(name, input, &block) 90: raise "Action needs a :description" unless input.include?(:description) 91: 92: unless @actions.include?(name) 93: @actions[name] = {} 94: @actions[name][:action] = name 95: @actions[name][:input] = {} 96: @actions[name][:output] = {} 97: @actions[name][:display] = :failed 98: @actions[name][:description] = input[:description] 99: end 100: 101: # if a block is passed it might be creating input methods, call it 102: # we set @current_action so the input block can know what its talking 103: # to, this is probably an epic hack, need to improve. 104: @current_action = name 105: block.call if block_given? 106: @current_action = nil 107: end
Sets the display preference to either :ok, :failed, :flatten or :always operates on action level
# File lib/mcollective/rpc/ddl.rb, line 157 157: def display(pref) 158: # defaults to old behavior, complain if its supplied and invalid 159: unless [:ok, :failed, :always].include?(pref) 160: raise "Display preference #{pref} :ok, :failed, :flatten or :always" 161: end 162: 163: action = @current_action 164: @actions[action][:display] = pref 165: end
# File lib/mcollective/rpc/ddl.rb, line 52 52: def findddlfile(agent) 53: @config.libdir.each do |libdir| 54: ddlfile = "#{libdir}/mcollective/agent/#{agent}.ddl" 55: if File.exist?(ddlfile) 56: Log.debug("Found #{agent} ddl at #{ddlfile}") 57: return ddlfile 58: end 59: end 60: return false 61: end
Generates help using the template based on the data created with metadata and input
# File lib/mcollective/rpc/ddl.rb, line 169 169: def help(template) 170: template = IO.readlines(template).join 171: meta = @meta 172: actions = @actions 173: 174: erb = ERB.new(template, 0, '%') 175: erb.result(binding) 176: 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 112 112: def input(argument, properties) 113: raise "Cannot figure out what action input #{argument} belongs to" unless @current_action 114: 115: action = @current_action 116: 117: [:prompt, :description, :type, :optional].each do |arg| 118: raise "Input needs a :#{arg}" unless properties.include?(arg) 119: end 120: 121: @actions[action][:input][argument] = {:prompt => properties[:prompt], 122: :description => properties[:description], 123: :type => properties[:type], 124: :optional => properties[:optional]} 125: 126: case properties[:type] 127: when :string 128: raise "Input type :string needs a :validation" unless properties.include?(:validation) 129: raise "String inputs need a :maxlength" unless properties.include?(:validation) 130: 131: @actions[action][:input][argument][:validation] = properties[:validation] 132: @actions[action][:input][argument][:maxlength] = properties[:maxlength] 133: 134: when :list 135: raise "Input type :list needs a :list argument" unless properties.include?(:list) 136: 137: @actions[action][:input][argument][:list] = properties[:list] 138: end 139: end
Registers meta data for the introspection hash
# File lib/mcollective/rpc/ddl.rb, line 64 64: def metadata(meta) 65: [:name, :description, :author, :license, :version, :url, :timeout].each do |arg| 66: raise "Metadata needs a :#{arg}" unless meta.include?(arg) 67: end 68: 69: @meta = meta 70: 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 144 144: def output(argument, properties) 145: raise "Cannot figure out what action input #{argument} belongs to" unless @current_action 146: raise "Output #{argument} needs a description" unless properties.include?(:description) 147: raise "Output #{argument} needs a description" unless properties.include?(:display_as) 148: 149: action = @current_action 150: 151: @actions[action][:output][argument] = {:description => properties[:description], 152: :display_as => properties[:display_as]} 153: 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 190 190: def validate_request(action, arguments) 191: # is the action known? 192: unless actions.include?(action) 193: raise DDLValidationError, "Attempted to call action #{action} for #{@agent} but it's not declared in the DDL" 194: end 195: 196: input = action_interface(action)[:input] 197: 198: input.keys.each do |key| 199: unless input[key][:optional] 200: unless arguments.keys.include?(key) 201: raise DDLValidationError, "Action #{action} needs a #{key} argument" 202: end 203: end 204: 205: # validate strings, lists and booleans, we'll add more types of validators when 206: # all the use cases are clear 207: # 208: # only does validation for arguments actually given, since some might 209: # be optional. We validate the presense of the argument earlier so 210: # this is a safe assumption, just to skip them. 211: # 212: # :string can have maxlength and regex. A maxlength of 0 will bypasss checks 213: # :list has a array of valid values 214: if arguments.keys.include?(key) 215: case input[key][:type] 216: when :string 217: raise DDLValidationError, "Input #{key} should be a string" unless arguments[key].is_a?(String) 218: 219: if input[key][:maxlength].to_i > 0 220: if arguments[key].size > input[key][:maxlength].to_i 221: raise DDLValidationError, "Input #{key} is longer than #{input[key][:maxlength]}" 222: end 223: end 224: 225: unless arguments[key].match(Regexp.new(input[key][:validation])) 226: raise DDLValidationError, "Input #{key} does not match validation regex #{input[key][:validation]}" 227: end 228: 229: when :list 230: unless input[key][:list].include?(arguments[key]) 231: raise DDLValidationError, "Input #{key} doesn't match list #{input[key][:list].join(', ')}" 232: end 233: 234: when :boolean 235: unless [TrueClass, FalseClass].include?(arguments[key].class) 236: raise DDLValidationError, "Input #{key} should be a boolean" 237: end 238: end 239: end 240: end 241: end