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#!/usr/bin/env python
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import json
import logging
import time
from kazoo.client import KazooClient, KazooState
from kazoo import exceptions as kze
from kazoo.recipe.lock import Lock
# States:
# We are building this node but it is not ready for use.
BUILDING = 'building'
# The node is ready for use.
READY = 'ready'
# The node should be deleted.
DELETING = 'deleting'
class LockException(Exception):
class ZooKeeper(object):
Class implementing the ZooKeeper interface.
This class uses the facade design pattern to keep common interaction
with the ZooKeeper API simple and consistent for the caller, and
limits coupling between objects. It allows for more complex interactions
by providing direct access to the client connection when needed (though
that is discouraged). It also provides for a convenient entry point for
testing only ZooKeeper interactions.
log = logging.getLogger("zuul.zk.ZooKeeper")
REQUEST_ROOT = '/nodepool/requests'
NODE_ROOT = '/nodepool/nodes'
def __init__(self):
Initialize the ZooKeeper object.
self.client = None
self._became_lost = False
def _dictToStr(self, data):
return json.dumps(data).encode('utf8')
def _strToDict(self, data):
return json.loads(data.decode('utf8'))
def _connection_listener(self, state):
Listener method for Kazoo connection state changes.
.. warning:: This method must not block.
if state == KazooState.LOST:
self.log.debug("ZooKeeper connection: LOST")
self._became_lost = True
elif state == KazooState.SUSPENDED:
self.log.debug("ZooKeeper connection: SUSPENDED")
self.log.debug("ZooKeeper connection: CONNECTED")
def connected(self):
return self.client.state == KazooState.CONNECTED
def suspended(self):
return self.client.state == KazooState.SUSPENDED
def lost(self):
return self.client.state == KazooState.LOST
def didLoseConnection(self):
return self._became_lost
def resetLostFlag(self):
self._became_lost = False
def connect(self, hosts, read_only=False):
Establish a connection with ZooKeeper cluster.
Convenience method if a pre-existing ZooKeeper connection is not
supplied to the ZooKeeper object at instantiation time.
:param str hosts: Comma-separated list of hosts to connect to (e.g.,,[::1]:2183).
:param bool read_only: If True, establishes a read-only connection.
if self.client is None:
self.client = KazooClient(hosts=hosts, read_only=read_only)
def disconnect(self):
Close the ZooKeeper cluster connection.
You should call this method if you used connect() to establish a
cluster connection.
if self.client is not None and self.client.connected:
self.client = None
def resetHosts(self, hosts):
Reset the ZooKeeper cluster connection host list.
:param str hosts: Comma-separated list of hosts to connect to (e.g.,,[::1]:2183).
if self.client is not None:
def submitNodeRequest(self, node_request, watcher):
Submit a request for nodes to Nodepool.
:param NodeRequest node_request: A NodeRequest with the
contents of the request.
:param callable watcher: A callable object that will be
invoked each time the request is updated. It is called
with two arguments: (node_request, deleted) where
node_request is the same argument passed to this method,
and deleted is a boolean which is True if the node no
longer exists (notably, this will happen on disconnection
from ZooKeeper). The watcher should return False when
further updates are no longer necessary.
priority = 100 # TODO(jeblair): integrate into nodereq
data = node_request.toDict()
data['created_time'] = time.time()
path = '%s/%s-' % (self.REQUEST_ROOT, priority)
path = self.client.create(path, self._dictToStr(data),
sequence=True, ephemeral=True)
reqid = path.split("/")[-1] = reqid
def callback(data, stat):
if data:
data = self._strToDict(data)
request_nodes = list(node_request.nodeset.getNodes())
for i, nodeid in enumerate(data.get('nodes', [])):
node_path = '%s/%s' % (self.NODE_ROOT, nodeid)
node_data, node_stat = self.client.get(node_path)
node_data = self._strToDict(node_data)
request_nodes[i].id = nodeid
deleted = (data is None) # data *are* none
return watcher(node_request, deleted)
self.client.DataWatch(path, callback)
def deleteNodeRequest(self, node_request):
Delete a request for nodes.
:param NodeRequest node_request: A NodeRequest with the
contents of the request.
path = '%s/%s' % (self.REQUEST_ROOT,
except kze.NoNodeError:
def storeNode(self, node):
'''Store the node.
The node is expected to already exist and is updated in its
:param Node node: The node to update.
path = '%s/%s' % (self.NODE_ROOT,
self.client.set(path, self._dictToStr(node.toDict()))
def lockNode(self, node, blocking=True, timeout=None):
Lock a node.
This should be called as soon as a request is fulfilled and
the lock held for as long as the node is in-use. It can be
used by nodepool to detect if Zuul has gone offline and the
node should be reclaimed.
:param Node node: The node which should be locked.
lock_path = '%s/%s/lock' % (self.NODE_ROOT,
lock = Lock(self.client, lock_path)
have_lock = lock.acquire(blocking, timeout)
except kze.LockTimeout:
raise LockException(
"Timeout trying to acquire lock %s" % lock_path)
# If we aren't blocking, it's possible we didn't get the lock
# because someone else has it.
if not have_lock:
raise LockException("Did not get lock on %s" % lock_path)
node.lock = lock
def unlockNode(self, node):
Unlock a node.
The node must already have been locked.
:param Node node: The node which should be unlocked.
if node.lock is None:
raise LockException("Node %s does not hold a lock" % (node,))
node.lock = None