menagerie

*menagerie* - (n.) a place where animals are kept and trained especially for exhibition

A ZooKeeper-backed Django settings holder.

.. image:: https://travis-ci.org/disqus/menagerie.png?branch=master :target: https://travis-ci.org/disqus/menagerie

Basic Usage

The menagerie.configure helper function provides a method to bootstrap your Django settings using the settings already available by normal methods (via the DJANGO_SETTINGS_MODULE environment variable), but uses the settings present in ZooKeeper to override these defaults.

To configure your application,

• Add a ZOOKEEPER_HOSTS setting to your Django settings file(s) that includes the network addresses of the ZooKeeper ensemble members to connect to as a list or tuple. For example:

  .. code:: python

  ZOOKEEPER_HOSTS = ('zookeeper-1.local', 'zookeeper-2.local')
  

  To bind the ZooKeeper client to a namespace other than the root namespace, add a ZOOKEEPER_SETTINGS_NAMESPACE setting containing the namespace.

• Add the following to the entry point(s) to your application (e.g. manage.py) before accessing any attributes of django.conf.settings:

  .. code:: python

  import menagerie
  menagerie.configure()
  

  It may be helpful to configure your logging to output DEBUG-level messages for the menagerie namespace to track down any errors you may encounter when configuring your application.

Storage

The settings storage is designed to be as simple as possible, and only uses the nodes within a single tree to represent all settings.

Trees are not traversed recursively -- all settings must be stored as the direct children of a shared root node, which defaults to / or the root of your ZooKeeper cluster/client namespace.

For example, the following tree of node names and values in ZooKeeper::

/DEBUG: true
/INTERNAL_IPS: ['127.0.0.1', '192.168.0.1']

...would yield the following settings::

settings.DEBUG == True
settings.INTERNAL_IPS == ['127.0.0.1', '192.168.0.1']

The deserializer doesn't do any sort of merging of complex types such as mappings or sequences -- either the values read from the ZooKeeper node data will be returned, or the default value if no value exists in the ZooKeeper tree.

Setting names that are valid as ZooKeeper node names but have language-specific semantics in Python (for example, names containing the . or - characters) may still be used, but will need to be accessed using getattr on the settings holder, like so:

.. code:: python

getattr(settings, 'MY-SPECIAL-SETTING')

Running Tests

The test suite can be run with make test.

The suite requires a working ZooKeeper installation, the path to which can be specified with the ZOOKEEPER_PATH environment variable. If you don't already have an installation of ZooKeeper, running make zookeeper will create one where the default path is located.