No longer maintained, supersceded by Kazoo: https://github.com/python-zk/kazoo
The aim of this project is providing a higher level API over the official low level Python ZooKeeper bindings (zkpython).
For django support see djkeeper.
* Automatic reconnection
* Recursive delete
* Recursive create
* Cached versions of: [get (cached_get), get_children (cached_get_children), exists (cached_exists)]
* Easy handling and masking of temporary disconnects/reconnects.
Either install the latest relase from PYPI:
$ pip install pykeeper
... or get the latest development version from GitHub:
$ pip install https://github.com/nkvoll/pykeeper/zipball/master#egg=pykeeper
Additionally, pykeeper requires a working installation of the official low level Python ZooKeeper bindings. These can either be built from source (recommended, explanation below), or you could install the statically compiled version zc-zookeeper-static) from PYPI, which may or may not work on your architecture/OS, and may or may not be the latest available ZooKeeper version.
If you don't have homebrew, follow the Linux installation below, skipping "ldconfig", otherwise, use homebrew to install zookeeper with the --python flag:
$ brew install --python zookeeper
Download and unpack the latest release of ZooKeeper from http://zookeeper.apache.org/releases.html:
$ tar -zxvf zookeeper-3.4.2.tar.gz
Build the C bindings:
$ cd zookeeper-3.4.2/src/c
$ ./configure --prefix=/usr/local
$ make
$ sudo make install
$ ldconfig
Build and install the python bindings:
$ cd ../contrib/zkpython
$ ant install
The test suite assumes you have a ZooKeeper server running on localhost:22181:
$ cd example
$ export ZOOCFGDIR=$(pwd) zkServer start-foreground
zkServer / zkServer.sh is found in the ZooKeeper installation directory.
The tests can then be run via the setup.py script:
$ python setup.py nosetests -with-doctest --verbosity=2
$ python
>>> import pykeeper
# (optional) redirect zookeeper logging to the python "logging" package, using the "zookeeper" logger.
# doing this prevents zookeeper from writing a lot of garbage to sys.stderr, and makes enables handling
# the logging output via the default python logging facilities. this behaviour is optional and can be
# switched off at any time later by calling pykeeper.uninstall_log_stream()
>>> pykeeper.install_log_stream()
# Create a ZooKeeper client and connect:
>>> client = pykeeper.ZooKeeper('localhost:22181')
>>> client.connect()
>>> client.get_children('/')
['zookeeper']
# creating a node:
>>> client.create_recursive('/bar/baz', '{"ok": true}')
>>> client.get_children('/')
['bar', 'zookeeper']
>>> bool(client.exists('/bar/baz'))
True
>>> client.get_children('/bar')
['baz']
>>> client.get('/bar/baz')
('{"ok": true}', {'pzxid': 3620L, 'ctime': 1328717487776L, 'aversion': 0, 'mzxid': 3620L, 'numChildren': 0, 'ephemeralOwner': 0L, 'version': 0, 'dataLength': 12, 'mtime': 1328717487776L, 'cversion': 0, 'czxid': 3620L})
# delete the node:
>>> client.delete_recursive('/bar')
>>> bool(client.exists('/bar'))
False
>>> client.get_children('/')
['foo', 'zookeeper']
# since the node does not exist, trying to get its data raises an exception:
>>> client.get('/bar')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pykeeper/client.py", line 176, in get
return zookeeper.get(self.handle, path, self._wrap_watcher(watcher))
zookeeper.NoNodeException: no node
If we lose connection to the ZooKeeper server, calls on the client will raise an exception:
>>> client.get('/')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pykeeper/client.py", line 176, in get
return zookeeper.get(self.handle, path, self._wrap_watcher(watcher))
zookeeper.ConnectionLossException: connection loss
We can wait until the connection is re-established by calling client.wait_until_connected() with an optional timeout. The default timeout is None, which means the call will block until the connection is re-established:
>>> client.state_name
'connecting'
>>> client.wait_until_connected()
>>> client.state_name
'connected'
If the connection is not re-established before the timeout occurs, a TimeoutException is raised:
>>> client.state_name
'connecting'
>>> client.wait_until_connected(timeout=10)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pykeeper/client.py", line 130, in wait_until_connected
raise TimeoutException()
pykeeper.client.TimeoutException
>>> client.state_name
'connecting'
A: Most likely, you attempted to do something along the following lines:
>>> import pykeeper
>>> client = pykeeper.ZooKeeper('localhost:22181')
>>> client.get_children('/')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pykeeper/client.py", line 153, in get_children
return zookeeper.get_children(self.handle, path, self._wrap_watcher(watcher))
TypeError: an integer is required
The problem is that you forgot to call client.connect() before using the client:
>>> import pykeeper
>>> client = pykeeper.ZooKeeper('localhost:22181')
>>> client.connect()
>>> client.get_children('/')
['zookeeper']
As usual, consider calling client.wait_until_connected(timeout=...) before using the client to ensure that the client has had time to connect to the ZooKeeper ensemble.
A: Always close clients you are not going to use any more by calling client.close(). Another solution is to re-use the clients instead of creating a new one every time you need one.
Currently, only the synchronous parts of the API is implemented.
MIT licensed, see LICENSE for details.