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python-etcd documentation
=========================
A python client for Etcd https://github.com/coreos/etcd
Official documentation: http://python-etcd.readthedocs.org/
.. image:: https://travis-ci.org/jplana/python-etcd.png?branch=master
:target: https://travis-ci.org/jplana/python-etcd
.. image:: https://coveralls.io/repos/jplana/python-etcd/badge.svg?branch=master&service=github
:target: https://coveralls.io/github/jplana/python-etcd?branch=master
Installation
------------
Pre-requirements
~~~~~~~~~~~~~~~~
Install etcd (2.0.1 or later). This version of python-etcd will only work correctly with the etcd version 2.0.x or later. If you are running an older version of etcd, please use python-etcd 0.3.3 or earlier.
This client is known to work with python 2.7 and with python 3.3 or above. It is not tested or expected to work in more outdated versions of python.
From source
~~~~~~~~~~~
.. code:: bash
$ python setup.py install
Usage
-----
The basic methods of the client have changed compared to previous versions, to reflect the new API structure; however a compatibility layer has been maintained so that you don't necessarily need to rewrite all your existing code.
Create a client object
~~~~~~~~~~~~~~~~~~~~~~
.. code:: python
import etcd
client = etcd.Client() # this will create a client against etcd server running on localhost on port 4001
client = etcd.Client(port=4002)
client = etcd.Client(host='127.0.0.1', port=4003)
client = etcd.Client(host='127.0.0.1', port=4003, allow_redirect=False) # wont let you run sensitive commands on non-leader machines, default is true
# If you have defined a SRV record for _etcd._tcp.example.com pointing to the clients
client = etcd.Client(srv_domain='example.com', protocol="https")
# create a client against https://api.example.com:443/etcd
client = etcd.Client(host='api.example.com', protocol='https', port=443, version_prefix='/etcd')
Write a key
~~~~~~~~~
.. code:: python
client.write('/nodes/n1', 1)
# with ttl
client.write('/nodes/n2', 2, ttl=4) # sets the ttl to 4 seconds
client.set('/nodes/n2', 1) # Equivalent, for compatibility reasons.
Read a key
~~~~~~~~~
.. code:: python
client.read('/nodes/n2').value
client.read('/nodes', recursive = True) #get all the values of a directory, recursively.
client.get('/nodes/n2').value
Delete a key
~~~~~~~~~~~~
.. code:: python
client.delete('/nodes/n1')
Atomic Compare and Swap
~~~~~~~~~~~~
.. code:: python
client.write('/nodes/n2', 2, prevValue = 4) # will set /nodes/n2 's value to 2 only if its previous value was 4 and
client.write('/nodes/n2', 2, prevExist = False) # will set /nodes/n2 's value to 2 only if the key did not exist before
client.write('/nodes/n2', 2, prevIndex = 30) # will set /nodes/n2 's value to 2 only if the key was last modified at index 30
client.test_and_set('/nodes/n2', 2, 4) #equivalent to client.write('/nodes/n2', 2, prevValue = 4)
You can also atomically update a result:
.. code:: python
result = client.read('/foo')
print(result.value) # bar
result.value += u'bar'
updated = client.update(result) # if any other client wrote '/foo' in the meantime this will fail
print(updated.value) # barbar
Watch a key
~~~~~~~~~~~
.. code:: python
client.read('/nodes/n1', wait = True) # will wait till the key is changed, and return once its changed
client.read('/nodes/n1', wait = True, timeout=30) # will wait till the key is changed, and return once its changed, or exit with an exception after 30 seconds.
client.read('/nodes/n1', wait = True, waitIndex = 10) # get all changes on this key starting from index 10
client.watch('/nodes/n1') #equivalent to client.read('/nodes/n1', wait = True)
client.watch('/nodes/n1', index = 10)
Locking module
~~~~~~~~~~~~~~
.. code:: python
# Initialize the lock object:
# NOTE: this does not acquire a lock yet
client = etcd.Client()
lock = etcd.Lock(client, 'my_lock_name')
# Use the lock object:
lock.acquire(blocking=True, # will block until the lock is acquired
lock_ttl=None) # lock will live until we release it
lock.is_acquired() #
lock.acquire(lock_ttl=60) # renew a lock
lock.release() # release an existing lock
lock.is_acquired() # False
# The lock object may also be used as a context manager:
client = etcd.Client()
with etcd.Lock(client, 'customer1') as my_lock:
do_stuff()
my_lock.is_acquired() # True
my_lock.acquire(lock_ttl = 60)
my_lock.is_acquired() # False
Get machines in the cluster
~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code:: python
client.machines
Get leader of the cluster
~~~~~~~~~~~~~~~~~~~~~~~~~
.. code:: python
client.leader
Generate a sequential key in a directory
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code:: python
x = client.write("/dir/name", "value", append=True)
print("generated key: " + x.key)
print("stored value: " + x.value)
List contents of a directory
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code:: python
#stick a couple values in the directory
client.write("/dir/name", "value1", append=True)
client.write("/dir/name", "value2", append=True)
directory = client.get("/dir/name")
# loop through directory children
for result in directory.children:
print(result.key + ": " + result.value)
# or just get the first child value
print(directory.children.next().value)
Development setup
-----------------
To create a buildout,
.. code:: bash
$ python bootstrap.py
$ bin/buildout
to test you should have etcd available in your system path:
.. code:: bash
$ bin/test
to generate documentation,
.. code:: bash
$ cd docs
$ make
Release HOWTO
-------------
To make a release
1) Update release date/version in NEWS.txt and setup.py
2) Run 'python setup.py sdist'
3) Test the generated source distribution in dist/
4) Upload to PyPI: 'python setup.py sdist register upload'
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