Build a new goal¶
This section gives some guidelines on how to implement and integrate custom goals with Watcher. If you wish to create a third-party package for your plugin, you can refer to our documentation for third-party package creation.
Before using any goal, please make sure that none of the existing goals fit your needs. Indeed, the underlying value of defining a goal is to be able to compare the efficacy of the action plans resulting from the various strategies satisfying the same goal. By doing so, Watcher can assist the administrator in his choices.
Create a new plugin¶
In order to create a new goal, you have to:
get_name()class method to return the unique ID of the new goal you want to create. This unique ID should be the same as the name of the entry point you will declare later on.
get_display_name()class method to return the translated display name of the goal you want to create. Note: Do not use a variable to return the translated string so it can be automatically collected by the translation tool.
get_translatable_display_name()class method to return the translation key (actually the english display name) of your new goal. The value return should be the same as the string translated in
get_efficacy_specification()method to return the efficacy specification for your goal.
Here is an example showing how you can define a new
NewGoal goal plugin:
# filepath: thirdparty/new.py
# import path: thirdparty.new
from watcher._i18n import _
from watcher.decision_engine.goal import base
from watcher.decision_engine.goal.efficacy import specs
return "new_goal" # Will be the name of the entry point
return _("New Goal")
return "New Goal"
As you may have noticed, the
method returns an
Unclassified() instance which
is provided by Watcher. This efficacy specification is useful during the
development process of your goal as it corresponds to an empty specification.
If you want to learn more about what efficacy specifications are used for or to
define your own efficacy specification, please refer to the related
Abstract Plugin Class¶
Here below is the abstract
- class watcher.decision_engine.goal.base.Goal(config)
- classmethod get_config_opts()
Defines the configuration options to be associated to this loadable
A list of configuration options relative to this Loadable
- Return type:
Add a new entry point¶
In order for the Watcher Decision Engine to load your new goal, the
goal must be registered as a named entry point under the
entry point namespace of your
setup.py file. If you are using pbr, this
entry point should be placed in your
The name you give to your entry point has to be unique and should be the same
as the value returned by the
get_name() class method of
Here below is how you would proceed to register
NewGoal using pbr:
new_goal = thirdparty.new:NewGoal
To get a better understanding on how to implement a more advanced goal, have
a look at the
Implement a customized efficacy specification¶
What is it for?¶
Efficacy specifications define a set of specifications for a given goal. These specifications actually define a list of indicators which are to be used to compute a global efficacy that outlines how well a strategy performed when trying to achieve the goal it is associated to.
The idea behind such specification is to give the administrator the possibility to run an audit using different strategies satisfying the same goal and be able to judge how they performed at a glance.
In order to create a new efficacy specification, you have to:
get_indicators_specifications()by returning a list of
IndicatorSpecificationinstance should actually extend the latter.
Each indicator specification should have a unique name which should be a valid Python variable name.
They should implement the
schemaabstract property by returning a
Schemainstance. This schema is the contract the strategy will have to comply with when setting the value associated to the indicator specification within its solution (see the architecture of Watcher for more information on the audit execution workflow).
get_global_efficacy()method: it should compute the global efficacy for the goal it achieves based on the efficacy indicators you just defined.
Here below is an example of an efficacy specification containing one indicator specification:
from watcher._i18n import _
from watcher.decision_engine.goal.efficacy import base as efficacy_base
from watcher.decision_engine.goal.efficacy import indicators
from watcher.decision_engine.solution import efficacy
description=_("Example of indicator specification."),
return voluptuous.Schema(voluptuous.Range(min=0), required=True)
def get_global_efficacy(self, indicators_map):
description="Example of global efficacy indicator",
value=indicators_map.indicator_example % 100)
To get a better understanding on how to implement an efficacy specification,
have a look at
Also, if you want to see a concrete example of an indicator specification,
have a look at