Gargoyle¶
Gargoyle is a platform built on top of Django which allows you to switch functionality of your application on and off based on conditions.
Note
Gargoyle works with Django 1.2, 1.3, or 1.4.
Installation¶
Install using pip:
pip install -U gargoyle
Or alternatively, easy_install:
easy_install -U gargoyle
Enable Gargoyle¶
Once you’ve downloaded the Gargoyle package, you simply need to add it to your INSTALLED_APPS:
INSTALLED_APPS = (
...
'gargoyle',
)
If you do not use Nexus, you will also need to enable discovery of gargoyle.py modules (which contain ConditionSets).
The best place to do this is within your urls.py file.
>>> import gargoyle
>>> gargoyle.autodiscover()
If you do use gargoyle.py files and the autodiscovery code, you’ll need to ensure your imports are not relative:
from __future__ import absolute_import
from gargoyle.conditions import ConditionSet
# ...
Nexus Frontend¶
While Gargoyle can be used without a frontend, we highly recommend using Nexus.
Nexus will automatically detect Gargoyle’s NexusModule, assuming you’re using autodiscovery. If not, you will need to register the module by hand:
>>> from gargoyle.nexus_modules import GargoyleModule
>>> nexus.site.register(GargoyleModule, 'gargoyle')
(Nexus is a replacement for your Django admin frontend, that works with django.contrib.admin)
Disabling Auto Creation¶
Under some conditions you may not want Gargoyle to automatically create switches that don’t currently exist. To disable this behavior,
you may use the GARGOYLE_AUTO_CREATE setting your settings.py:
GARGOYLE_AUTO_CREATE = False
Default Switch States¶
The GARGOYLE_SWITCH_DEFAULTS setting allows engineers to set the default state of a switch before it’s been added via the gargoyle admin interface. In your settings.py add something like:
GARGOYLE_SWITCH_DEFAULTS = {
'new_switch': {
'is_active': True,
'label': 'New Switch',
'description': 'When you want the newness',
},
'funky_switch': {
'is_active': False,
'label': 'Funky Switch',
'description': 'Controls the funkiness.',
},
}
Usage¶
Gargoyle is designed to work around a very simple API. Generally, you pass in the switch key and a list of instances to check this key against.
@switch_is_active¶
The simplest way to use Gargoyle is as a decorator. The decorator will automatically integrate with
filters registered to the User model, as well as IP address (using RequestConditionSet):
from gargoyle.decorators import switch_is_active
@switch_is_active('my switch name')
def my_view(request):
return 'foo'
In the case of the switch being inactive and you are using the decorator, a 404 error is raised. You may also redirect the user to an absolute URL (relative to domain), or a named URL pattern:
# if redirect_to starts with a /, we assume it's a url path
@switch_is_active('my switch name', redirect_to='/my/url/path')
# alternatively use the url mapper
@switch_is_active('my switch name', redirect_to='access_denied')
gargoyle.is_active¶
An alternative, more flexible use of Gargoyle is with the is_active method. This allows you
to perform validation on your own custom objects:
from gargoyle import gargoyle
def my_function(request):
if gargoyle.is_active('my switch name', request):
return 'foo'
else:
return 'bar'
# with custom objects
from gargoyle import gargoyle
def my_method(user):
if gargoyle.is_active('my switch name', user):
return 'foo'
else:
return 'bar'
ifswitch¶
If you prefer to use templatetags, Gargoyle provides a helper called ifswitch to give you easy conditional blocks based on active switches (for the request):
{% load gargoyle_tags %}
{% ifswitch switch_name %}
switch_name is active!
{% else %}
switch_name is not active :(
{% endifswitch %}
ifswitch can also be used with custom objects, like the gargoyle.is_active method:
{% ifswitch "my switch name" user %}
"my switch name" is active!
{% endifswitch %}
Switch Inheritance¶
Switches utilizing the named pattern of parent:child will automatically inherit state from their parents. For example,
if your switch, parent:child is globally enabled, but parent is disabled, when is_active('parent:child') is called
it will return False.
A parent switch that has it’s status set to inherit will return the default value for a switch, which is False (the same as
disabled).
Note
Currently inheritance does not combine filters. If your child defines any filters, they will override all of the parents.
Testing Switches¶
Gargoyle includes a context manager, which may optionally be used as a decorator, to give temporary state to a switch on the currently executing thread.
from gargoyle.testutils import switches
@switches(my_switch_name=True)
def foo():
print gargoyle.is_active('my_switch_name')
def foo():
with switches(my_switch_name=True):
print gargoyle.is_active('my_switch_name')
You may also optionally pass an instance of SwitchManager
as the first argument:
def foo():
with switches(gargoyle, my_switch_name=True):
print gargoyle.is_active('my_switch_name')
API Reference¶
Condition Set API reference¶
This document describes the Condition Set API, which allows you to create your own custom switch validation logic.
Manager API reference¶
This document describes the Switch Manager API. This is generally referred to
as the global gargoyle object, which lives in gargoyle.gargoyle.
Switches are handled through the ModelDict interface, which is registered under the Switch model.
Signals¶
-
gargoyle.signals.switch_added This signal is sent when a switch is added (similar to Django’s post_save, when created is True).
Example subscriber:
def switch_added_callback(sender, request, switch, **extra): logging.debug('Switch was added: %r', switch.label) from gargoyle.signals import switch_added switch_added.connect(switch_added_callback)
-
gargoyle.signals.switch_deleted This signal is sent when a switch is deleted (similar to Django’s post_delete).
Example subscriber:
def switch_deleted_callback(sender, request, switch, **extra): logging.debug('Switch was deleted: %r', switch.label) from gargoyle.signals import switch_deleted switch_deleted.connect(switch_deleted_callback)
-
gargoyle.signals.switch_updated This signal is sent when a switch is updated (similar to Django’s post_save, when created is False).
Example subscriber:
def switch_updated_callback(sender, request, switch, **extra): logging.debug('Switch was updated: %r', switch.label) from gargoyle.signals import switch_updated switch_updated.connect(switch_updated_callback)
-
gargoyle.signals.switch_status_updated This signal is sent when a condition is removed from a switch.
Example subscriber:
def switch_status_updated_callback(sender, request, switch, status, **extra): logging.debug('Switch has updated status: %r; %r', switch.label, status) from gargoyle.signals import switch_status_updated switch_status_updated.connect(switch_status_updated_callback)
-
gargoyle.signals.switch_condition_added This signal is sent when a condition is added to a switch.
Example subscriber:
def switch_condition_added_callback(sender, request, switch, condition, **extra): logging.debug('Switch has new condition: %r; %r', switch.label, condition) from gargoyle.signals import switch_condition_added switch_condition_added.connect(switch_condition_added_callback)
-
gargoyle.signals.switch_condition_deleted This signal is sent when a condition is removed from a switch.
Example subscriber:
def switch_condition_deleted_callback(sender, request, switch, condition, **extra): logging.debug('Switch has deleted condition: %r; %r', switch.label, condition) from gargoyle.signals import switch_condition_deleted switch_condition_deleted.connect(switch_condition_deleted_callback)
Test Utilities¶
