Welcome to distconfig’s documentation!

Library to manage distributed configuration using either ZooKeeper or Etcd or Consul.

Contents:

Installation

To use ZooKeeper as backend you should install distconfig using

$ pip install distconfig[zookeeper]

with etcd:

$ pip install distconfig[etcd]

with consul:

$ pip install distconfig[consul]

To use distconfig with gevent you can do

$ pip install distconfig[zookeeper, gevent]

Usage

Example using zookeeper as a backend

import kazoo

from distconfig import Proxy

client = kazoo.Client()

proxy = Proxy.configure(
    'distconfig.backends.zookeeper.ZooKeeperBackend',
    client=client,
)

# config is a read only mapping-like object.
config = proxy.get_config('/distconfig/service_name/config')

print config['key']

# Getting nested values works by supplying dotted key, this of course
# mean that key cannot have a dot in them.
print config['key.inner']

# You can assert key value type by using typed get function e.g.
# get_int, get_float, get_unicode, get_bytes ... .
print config.get_int('key.inner.int_key')

# Getting a inner config.
print config.get_config('key.inner.dict_key')

API Docs

Contents:

Backend Proxy

class distconfig.api.Proxy(backend)

Proxy class for differents backend.

backend

Readonly property for backend.

classmethod configure(backend_qualname, **backend_options)

Configure backend.

Parameters:
  • backend_qualname – Backend class qualifed name (dotted-name) e.g. distconfig.backends.zookeeper.ZooKeeperBackend.
  • logger – logging.Logger instance to use for logging.
  • parser – Callable that accept the raw config data saved in the backend and should return the config data parsed, default: ujson.loads.
  • backend_options – Keyword arguments to pass to backend class.
get_config(path, config_cls=<class 'distconfig.config.Config'>)

Get configuration from path.

Parameters:
  • path – Location of the configuratin in the backend.
  • config_cls – configuration class to return, default: distconfig.config.Config.
Returns:

config_cls instance.

Configuration Management

class distconfig.config.Config(data)

Read only mapping-like for holding configuration.

Note: At the opposite of ConfigParser.RawConfigParser in stdlib, methods like get_<type> in this class do not coerse, instead the use case is type assertion, i.e. When a user call Config.get_int on a key where the value is a string e.g. ‘2’, the call will fail with a TypeError.

get(path, default=None, type_=None)

Same as dict.get(k[,d]) with an extra argument type_ that assert type matching if given.

path argument can be in the form ‘key1/key2/key3’ as a shortcut for doing config['key1']['key2']['key3']. In case a key have a / in it, we can escape it like so ‘key1/key2/key3’ this will be translated to config['key1/key2']['key3']

Parameters:
  • path – path expression e.g. ‘key1/key2/key3’
  • default – default value to return when key is missing, in case it’s supplied default with type_, default must be of of type type_, default: None.
  • type – Python type to validate returned value, default: None.
Returns:

the value of the requested path as a string.
Raises:
  • TypeError – if path value is not of type type_.
  • KeyError – if path doesn’t exist and default is set to distconfig.config.UNDEFINED.
get_boolean(path, default=<object object at 0x7f1b6bcf92c0>)

Get path value as boolean.

Parameters:
  • path – path expression e.g. ‘key1.key2.key3’
  • default – default value to return when key is missing, if supplied default must be of type boolean, default: UNDEFINED.
Returns:

the value of the requested path as a Boolean.
Raises:
  • TypeError – if path value is not of type type_.
  • KeyError – if path doesn’t exist and no default was given.
get_bytes(path, default=<object object at 0x7f1b6bcf92c0>)

Get path value as bytes.

Parameters:
  • path – path expression e.g. ‘key1.key2.key3’
  • default – default value to return when key is missing, if supplied default must be of type bytes, default: UNDEFINED.
Returns:

the value of the requested path as a Unicode.
Raises:
  • TypeError – if path value is not of type type_.
  • KeyError – if path doesn’t exist and no default was given.
get_config(path, default=<object object at 0x7f1b6bcf92c0>)

Get path value as Config.

Parameters:
  • path – path expression e.g. ‘key1.key2.key3’
  • default – default value to return when key is missing, if supplied default must be of type dict, default: UNDEFINED.
Returns:

the value of the requested path as a Config instance.
Raises:
  • TypeError – if path value is not of type type_.
  • KeyError – if path doesn’t exist and no default was given.
get_float(path, default=<object object at 0x7f1b6bcf92c0>)

Get path value as float.

Parameters:
  • path – path expression e.g. ‘key1.key2.key3’
  • default – default value to return when key is missing, if supplied default must be of type float, default: UNDEFINED.
Returns:

the value of the requested path as a Float.
Raises:
  • TypeError – if path value is not of type type_.
  • KeyError – if path doesn’t exist and no default was given.
get_int(path, default=<object object at 0x7f1b6bcf92c0>)

Get path value as integer.

Parameters:
  • path – path expression e.g. ‘key1.key2.key3’
  • default – default value to return when key is missing, if supplied default must be of type integer, default: UNDEFINED.
Returns:

the value of the requested path as a Integer.
Raises:
  • TypeError – if path value is not of type type_.
  • KeyError – if path doesn’t exist and no default was given.
get_unicode(path, default=<object object at 0x7f1b6bcf92c0>)

Get path value as unicode.

Parameters:
  • path – path expression e.g. ‘key1.key2.key3’
  • default – default value to return when key is missing, if supplied default must be of type unicode, default: UNDEFINED.
Returns:

the value of the requested path as a Unicode.
Raises:
  • TypeError – if path value is not of type type_.
  • KeyError – if path doesn’t exist and no default was given.

Backends

Base class

class distconfig.backends.base.BaseBackend(parser=<built-in function loads>, logger=<logging.Logger object at 0x7f1b6b8f2050>)

Base abstract backend class.

Backend implementation should inherit and implement get_raw method.

Parameters:
  • parser – Callable that accept a string and parse it, default: ujson.loads.
  • logger – logging.Logger` instance.
add_listener(callback)

Add callback to be called when data change in the backend.

If the same callback is added more than once, then it will be notified more than once. That is, no check is made to ensure uniqueness.

Parameters:callback – Callable that accept one argument the new data.
get(path)

Get parsed path value in backend.

Path:key in the backend.
Returns:path value parsed.
get_raw(path)

Get path value from backend as it is.

Path:key in the backend.
Returns:path value as saved in backend or None if not found in backend.
remove_listener(callback)

Remove previously added callback.

If callback had been added more than once, then only the first occurrence will be removed.

Parameters:callback – Callable as with :meth: add_listener.
Raises ValueError:
 In case callback was not previously registered.

Existing backends

The current backends exist out of the box:

class distconfig.backends.consul.ConsulBackend(client, execution_context=<distconfig.backends.execution_context.ThreadingExecutionContext object at 0x7f1b6b36aa90>, **kwargs)

Consul backend implementation.

Parameters:
  • client – Instance of consul.Consul.
  • execution_context – Instance of distconfig.backends.execution_context.ExecutionContext

Execution Contexts

class distconfig.backends.execution_context.GeventExecutionContext

Execution context that run background function as a Greenlet.

gevent monkey patching must be done by user.

run(func, *args, **kwargs)

Run given function in a Greenlet.

class distconfig.backends.execution_context.ThreadingExecutionContext

Execution context that run background function as a OS Thread.

run(func, *args, **kwargs)

Run given function in a daemon OS thread.

Indices and tables