2010-05-20 20:35:15 -07:00

127 lines
5.0 KiB
Ruby

module Vagrant
module Actions
# Base class for any command actions.
#
# Actions are the smallest unit of functionality found within
# Vagrant. Vagrant composes many actions together to execute
# its complex tasks while keeping the individual pieces of a
# task as discrete reusable actions. Actions are ran exclusively
# by an {Runner action runner} which is simply a subclass of {Runner}.
#
# Actions work by implementing any or all of the following methods
# which a {Runner} executes:
#
# * `prepare` - Called once for each action before any action has `execute!`
# called. This is meant for basic setup.
# * `execute!` - This is where the meat of the action typically goes;
# the main code which executes the action.
# * `cleanup` - This is called exactly once for each action after every
# other action is completed. It is meant for cleaning up any resources.
# * `rescue` - This is called if an exception occurs in _any action_. This
# gives every other action a chance to clean itself up.
#
# For details of each step of an action, read the specific function call
# documentation below.
class Base
# The {Runner runner} which is executing the action
attr_reader :runner
# Included so subclasses don't need to include it themselves.
include Vagrant::Util
# A helper method for logging which simply gets the logger from
# the runner. Since actions tend to log quite a bit, this
# removes the need to prefix `logger` with `@runner` over and
# over.
def logger
runner.env.logger
end
# Initialization of the action, passing any arguments which may have
# been given to the {Runner runner}. This method can be used by subclasses
# to save any of the configuration options which are passed in.
def initialize(runner, *args)
@runner = runner
end
# This method is called once per action, allowing the action
# to setup any callbacks, add more events, etc. Prepare is
# called in the order the actions are defined, and the action
# itself has no control over this.
#
# Examples of its usage:
#
# Perhaps we need an additional action only if a configuration is set:
#
# def prepare
# @vm.actions << FooAction if Vagrant.config[:foo] == :bar
# end
#
def prepare; end
# This method is called once, after preparing, to execute the
# actual task. This method is responsible for calling any
# callbacks. Adding new actions here will have unpredictable
# effects and should never be done.
#
# Examples of its usage:
#
# def execute!
# @vm.invoke_callback(:before_oven, "cookies")
# # Do lots of stuff here
# @vm.invoke_callback(:after_oven, "more", "than", "one", "option")
# end
#
def execute!; end
# This method is called after all actions have finished executing.
# It is meant as a place where final cleanup code can be done, knowing
# that all other actions are finished using your data.
def cleanup; end
# This method is only called if some exception occurs in the chain
# of actions. If an exception is raised in any action in the current
# chain, then every action part of that chain has {#rescue} called
# before raising the exception further. This method should be used to
# perform any cleanup necessary in the face of errors.
#
# **Warning:** Since this method is called when an exception is already
# raised, be _extra careful_ when implementing this method to handle
# all your own exceptions, otherwise it'll mask the initially raised
# exception.
def rescue(exception); end
# The following two methods are used for declaring action dependencies.
# For example, you require that the reload action be in place before
# a your new FooAction you might do the following
#
# def follows; [Reload] end
# This method is called when the runner is determining the actions that
# must precede a given action. You would say "This action follows [Action1, Action2]"
def follows; [] end
# This method is called when the runner is determining the actions that
# must follow a given action. You would say "This action precedes [Action3, Action4]
def precedes; [] end
end
# An exception which occured within an action. This should be used instead of
# {Vagrant::Util#error_and_exit error_and_exit}, since it allows the {Runner} to call
# {Base#rescue rescue} on all the actions and properly exit. Any message
# passed into the {ActionException} is then shown and and vagrant exits.
class ActionException < Exception
attr_reader :key
attr_reader :data
def initialize(key, data = {})
@key = key
@data = data
message = Vagrant::Util::Translator.t(key, data)
super(message)
end
end
end
end