A python client for Etcd https://github.com/coreos/etcd
Official documentation: http://python-etcd.readthedocs.org/
This version of python-etcd will only work correctly with the etcd server 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 It is not tested or expected to work in more outdated versions of python.
$ python setup.py install
$ python3.5 -m pip install python-etcd
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
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', 4001), ('127.0.0.1', 4002), ('127.0.0.1', 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
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
client.read('/nodes/n2').value client.read('/nodes', recursive = True) #get all the values of a directory, recursively. client.get('/nodes/n2').value # raises etcd.EtcdKeyNotFound when key not found try: client.read('/invalid/path') except etcd.EtcdKeyNotFound: # do something print "error"
Delete a key
Atomic Compare and Swap
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:
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
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)
Refreshing key TTL
(Since etcd 2.3.0) Keys in etcd can be refreshed without notifying current watchers.
This can be achieved by setting the refresh to true when updating a TTL.
You cannot update the value of a key when refreshing it.
client.write('/nodes/n1', 'value', ttl=30) # sets the ttl to 30 seconds client.refresh('/nodes/n1', ttl=600) # refresh ttl to 600 seconds, without notifying current watchers
# Initialize the lock object: # NOTE: this does not acquire a lock yet client = etcd.Client() # Or you can custom lock prefix, default is '/_locks/' if you are using HEAD client = etcd.Client(lock_prefix='/my_etcd_root/_locks') 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 # True 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
Get leader of the cluster
Generate a sequential key in a directory
x = client.write("/dir/name", "value", append=True) print("generated key: " + x.key) print("stored value: " + x.value)
List contents of a directory
#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)
To create a buildout,
$ python bootstrap.py $ bin/buildout
to test you should have etcd available in your system path:
to generate documentation,
$ cd docs $ make
To make a release
- Update release date/version in NEWS.txt and setup.py
- Run 'python setup.py sdist'
- Test the generated source distribution in dist/
- Upload to PyPI: 'python setup.py sdist register upload'