A class that helps creating data description language files for plugins. You can define meta data, actions, input and output describing the behavior of your agent or other plugins
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
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.rb, line 160 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.rb, line 316 def action_interface(name) raise "Only agent DDLs have actions" unless @plugintype == :agent @entities[name] || {} end
Returns an array of actions this agent support
# File lib/mcollective/ddl.rb, line 304 def actions raise "Only agent DDLs have actions" unless @plugintype == :agent @entities.keys end
Sets the aggregate array for the given action
# File lib/mcollective/ddl.rb, line 262 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
records valid capabilities for discovery plugins
# File lib/mcollective/ddl.rb, line 127 def capabilities(caps) raise "Only discovery DDLs have capabilities" unless @plugintype == :discovery caps = [caps].flatten raise "Discovery plugin capabilities can't be empty" if caps.empty? caps.each do |cap| if [:classes, :facts, :identity, :agents, :compound].include?(cap) @entities[:discovery][:capabilities] << cap else raise "%s is not a valid capability, valid capabilities are :classes, :facts, :identity, :agents and :compound" % cap end end end
Creates the definition for a data query
dataquery :description => "Match data using Augeas" do input :query, :prompt => "Matcher", :description => "Valid Augeas match expression", :type => :string, :validation => /.+/, :maxlength => 50 output :size, :description => "The amount of records matched", :display_as => "Matched" end
# File lib/mcollective/ddl.rb, line 98 def dataquery(input, &block) raise "Data queries need a :description" unless input.include?(:description) raise "Data queries can only have one definition" if @entities[:data] @entities[:data] = {:description => input[:description], :input => {}, :output => {}} @current_entity = :data block.call if block_given? @current_entity = nil end
Returns the interface for the data query
# File lib/mcollective/ddl.rb, line 310 def dataquery_interface raise "Only data DDLs have data queries" unless @plugintype == :data @entities[:data] || {} end
Creates the definition for new discovery plugins
discovery do capabilities [:classes, :facts, :identity, :agents, :compound] end
# File lib/mcollective/ddl.rb, line 116 def discovery(&block) raise "Discovery plugins can only have one definition" if @entities[:discovery] @entities[:discovery] = {:capabilities => []} @current_entity = :discovery block.call if block_given? @current_entity = nil end
# File lib/mcollective/ddl.rb, line 321 def discovery_interface raise "Only discovery DDLs have discovery interfaces" unless @plugintype == :discovery @entities[:discovery] end
Sets the display preference to either :ok, :failed, :flatten or :always operates on action level
# File lib/mcollective/ddl.rb, line 235 def display(pref) # 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.rb, line 60 def findddlfile(ddlname=nil, ddltype=nil) ddlname = @pluginname unless ddlname ddltype = @plugintype unless ddltype @config.libdir.each do |libdir| ddlfile = File.join([libdir, "mcollective", ddltype.to_s, "#{ddlname}.ddl"]) if File.exist?(ddlfile) Log.debug("Found #{ddlname} ddl at #{ddlfile}") return ddlfile end end return false end
Generates help using the template based on the data created with metadata and input.
If no template name is provided one will be chosen based on the plugin type. If the provided template path is not absolute then the template will be loaded relative to helptemplatedir configuration parameter
# File lib/mcollective/ddl.rb, line 291 def help(template=nil) template = template_for_plugintype unless template template = File.join(@config.helptemplatedir, template) unless template.start_with?(File::SEPARATOR) template = File.read(template) meta = @meta entities = @entities erb = ERB.new(template, 0, '%') erb.result(binding) end
Registers an input argument for a given action
See the documentation for action for how to use this
# File lib/mcollective/ddl.rb, line 183 def input(argument, properties) raise "Cannot figure out what entity input #{argument} belongs to" unless @current_entity entity = @current_entity raise "The only valid input name for a data query is 'query'" if @plugintype == :data && argument != :query if @plugintype == :agent raise "Input needs a :optional property" unless properties.include?(:optional) end [:prompt, :description, :type].each do |arg| raise "Input needs a :#{arg} property" unless properties.include?(arg) end @entities[entity][:input][argument] = {:prompt => properties[:prompt], :description => properties[:description], :type => properties[:type], :optional => properties[:optional]} case properties[:type] when :string raise "Input type :string needs a :validation argument" unless properties.include?(:validation) raise "Input type :string needs a :maxlength argument" unless properties.include?(:maxlength) @entities[entity][:input][argument][:validation] = properties[:validation] @entities[entity][:input][argument][:maxlength] = properties[:maxlength] when :list raise "Input type :list needs a :list argument" unless properties.include?(:list) @entities[entity][:input][argument][:list] = properties[:list] end 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.rb, line 434 def is_function?(method_name) PluginManager.find("aggregate").include?(method_name.to_s) end
# File lib/mcollective/ddl.rb, line 52 def loadddlfile if ddlfile = findddlfile instance_eval(File.read(ddlfile), ddlfile, 1) else raise("Can't find DDL for #{@plugintype} plugin '#{@pluginname}'") end end
Registers meta data for the introspection hash
# File lib/mcollective/ddl.rb, line 76 def metadata(meta) [:name, :description, :author, :license, :version, :url, :timeout].each do |arg| raise "Metadata needs a :#{arg} property" unless meta.include?(arg) end @meta = meta end
If the ddl’s plugin type is ‘agent’ and the method name matches a aggregate function, we return the function with args as a hash.
# File lib/mcollective/ddl.rb, line 424 def method_missing(name, *args, &block) super unless @process_aggregate_functions super unless is_function?(name) return {:function => name, :args => args} end
Registers an output argument for a given action
See the documentation for action for how to use this
# File lib/mcollective/ddl.rb, line 221 def output(argument, properties) raise "Cannot figure out what action input #{argument} belongs to" unless @current_entity raise "Output #{argument} needs a description argument" unless properties.include?(:description) raise "Output #{argument} needs a display_as argument" unless properties.include?(:display_as) action = @current_entity @entities[action][:output][argument] = {:description => properties[:description], :display_as => properties[:display_as], :default => properties[:default]} 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.rb, line 253 def summarize(&block) unless @config.mode == :server @process_aggregate_functions = true block.call @process_aggregate_functions = nil end end
# File lib/mcollective/ddl.rb, line 275 def template_for_plugintype case @plugintype when :agent return "rpc-help.erb" else return "#{@plugintype}-help.erb" end end
validate strings, lists and booleans, we’ll add more types of validators when all the use cases are clear
only does validation for arguments actually given, since some might be optional. We validate the presense of the argument earlier so this is a safe assumption, just to skip them.
:string can have maxlength and regex. A maxlength of 0 will bypasss checks :list has a array of valid values
# File lib/mcollective/ddl.rb, line 335 def validate_input_argument(input, key, argument) case input[key][:type] when :string raise DDLValidationError, "Input #{key} should be a string for plugin #{meta[:name]}" unless argument.is_a?(String) if input[key][:maxlength].to_i > 0 if argument.size > input[key][:maxlength].to_i raise DDLValidationError, "Input #{key} is longer than #{input[key][:maxlength]} character(s) for plugin #{meta[:name]}" end end unless argument.match(Regexp.new(input[key][:validation])) raise DDLValidationError, "Input #{key} does not match validation regex #{input[key][:validation]} for plugin #{meta[:name]}" end when :list unless input[key][:list].include?(argument) raise DDLValidationError, "Input #{key} doesn't match list #{input[key][:list].join(', ')} for plugin #{meta[:name]}" end when :boolean unless [TrueClass, FalseClass].include?(argument.class) raise DDLValidationError, "Input #{key} should be a boolean for plugin #{meta[:name]}" end when :integer raise DDLValidationError, "Input #{key} should be a integer for plugin #{meta[:name]}" unless argument.is_a?(Fixnum) when :float raise DDLValidationError, "Input #{key} should be a floating point number for plugin #{meta[:name]}" unless argument.is_a?(Float) when :number raise DDLValidationError, "Input #{key} should be a number for plugin #{meta[:name]}" unless argument.is_a?(Numeric) end return true 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.rb, line 375 def validate_rpc_request(action, arguments) raise "Can only validate RPC requests against Agent DDLs" unless @plugintype == :agent # 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
# File lib/mcollective/ddl.rb, line 38 def initialize(plugin, plugintype=:agent, loadddl=true) @entities = {} @meta = {} @config = Config.instance @pluginname = plugin @plugintype = plugintype.to_sym # used to track if the method_missing that handles the # aggregate functions should do so or not @process_aggregate_functions = nil loadddlfile if loadddl end
As we’re taking arguments on the command line we need a way to input booleans, true on the cli is a string so this method will take the ddl, find all arguments that are supposed to be boolean and if they are the strings “true”/“yes” or “false”/“no” turn them into the matching boolean
# File lib/mcollective/ddl.rb, line 405 def self.string_to_boolean(val) return true if ["true", "t", "yes", "y", "1"].include?(val.downcase) return false if ["false", "f", "no", "n", "0"].include?(val.downcase) raise "#{val} does not look like a boolean argument" end
a generic string to number function, if a number looks like a float it turns it into a float else an int. This is naive but should be sufficient for numbers typed on the cli in most cases
# File lib/mcollective/ddl.rb, line 415 def self.string_to_number(val) return val.to_f if val =~ /^\d+\.\d+$/ return val.to_i if val =~ /^\d+$/ raise "#{val} does not look like a number" end
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