495 lines
16 KiB
Python
495 lines
16 KiB
Python
# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import json
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import logging
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import time
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from kazoo.client import KazooClient, KazooState
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from kazoo import exceptions as kze
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from kazoo.handlers.threading import KazooTimeoutError
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from kazoo.recipe.lock import Lock
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import zuul.model
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class LockException(Exception):
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pass
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class ZooKeeper(object):
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'''
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Class implementing the ZooKeeper interface.
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This class uses the facade design pattern to keep common interaction
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with the ZooKeeper API simple and consistent for the caller, and
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limits coupling between objects. It allows for more complex interactions
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by providing direct access to the client connection when needed (though
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that is discouraged). It also provides for a convenient entry point for
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testing only ZooKeeper interactions.
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'''
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log = logging.getLogger("zuul.zk.ZooKeeper")
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REQUEST_ROOT = '/nodepool/requests'
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REQUEST_LOCK_ROOT = "/nodepool/requests-lock"
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NODE_ROOT = '/nodepool/nodes'
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# Log zookeeper retry every 10 seconds
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retry_log_rate = 10
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def __init__(self):
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'''
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Initialize the ZooKeeper object.
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'''
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self.client = None
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self._became_lost = False
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self._last_retry_log = 0
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def _dictToStr(self, data):
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return json.dumps(data).encode('utf8')
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def _strToDict(self, data):
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return json.loads(data.decode('utf8'))
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def _connection_listener(self, state):
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'''
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Listener method for Kazoo connection state changes.
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.. warning:: This method must not block.
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'''
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if state == KazooState.LOST:
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self.log.debug("ZooKeeper connection: LOST")
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self._became_lost = True
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elif state == KazooState.SUSPENDED:
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self.log.debug("ZooKeeper connection: SUSPENDED")
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else:
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self.log.debug("ZooKeeper connection: CONNECTED")
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@property
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def connected(self):
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return self.client.state == KazooState.CONNECTED
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@property
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def suspended(self):
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return self.client.state == KazooState.SUSPENDED
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@property
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def lost(self):
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return self.client.state == KazooState.LOST
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@property
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def didLoseConnection(self):
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return self._became_lost
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def resetLostFlag(self):
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self._became_lost = False
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def logConnectionRetryEvent(self):
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now = time.monotonic()
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if now - self._last_retry_log >= self.retry_log_rate:
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self.log.warning("Retrying zookeeper connection")
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self._last_retry_log = now
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def connect(self, hosts, read_only=False, timeout=10.0):
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'''
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Establish a connection with ZooKeeper cluster.
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Convenience method if a pre-existing ZooKeeper connection is not
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supplied to the ZooKeeper object at instantiation time.
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:param str hosts: Comma-separated list of hosts to connect to (e.g.
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127.0.0.1:2181,127.0.0.1:2182,[::1]:2183).
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:param bool read_only: If True, establishes a read-only connection.
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:param float timeout: The ZooKeeper session timeout, in
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seconds (default: 10.0).
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'''
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if self.client is None:
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self.client = KazooClient(hosts=hosts, read_only=read_only,
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timeout=timeout)
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self.client.add_listener(self._connection_listener)
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# Manually retry initial connection attempt
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while True:
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try:
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self.client.start(1)
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break
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except KazooTimeoutError:
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self.logConnectionRetryEvent()
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def disconnect(self):
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'''
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Close the ZooKeeper cluster connection.
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You should call this method if you used connect() to establish a
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cluster connection.
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'''
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if self.client is not None and self.client.connected:
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self.client.stop()
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self.client.close()
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self.client = None
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def resetHosts(self, hosts):
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'''
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Reset the ZooKeeper cluster connection host list.
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:param str hosts: Comma-separated list of hosts to connect to (e.g.
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127.0.0.1:2181,127.0.0.1:2182,[::1]:2183).
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'''
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if self.client is not None:
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self.client.set_hosts(hosts=hosts)
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def submitNodeRequest(self, node_request, watcher):
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'''
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Submit a request for nodes to Nodepool.
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:param NodeRequest node_request: A NodeRequest with the
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contents of the request.
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:param callable watcher: A callable object that will be
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invoked each time the request is updated. It is called
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with two arguments: (node_request, deleted) where
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node_request is the same argument passed to this method,
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and deleted is a boolean which is True if the node no
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longer exists (notably, this will happen on disconnection
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from ZooKeeper). The watcher should return False when
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further updates are no longer necessary.
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'''
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node_request.created_time = time.time()
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data = node_request.toDict()
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path = '%s/%s-' % (self.REQUEST_ROOT, node_request.priority)
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path = self.client.create(path, self._dictToStr(data),
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makepath=True,
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sequence=True, ephemeral=True)
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reqid = path.split("/")[-1]
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node_request.id = reqid
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def callback(data, stat):
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if data:
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self.updateNodeRequest(node_request, data)
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deleted = (data is None) # data *are* none
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return watcher(node_request, deleted)
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self.client.DataWatch(path, callback)
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def deleteNodeRequest(self, node_request):
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'''
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Delete a request for nodes.
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:param NodeRequest node_request: A NodeRequest with the
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contents of the request.
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'''
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path = '%s/%s' % (self.REQUEST_ROOT, node_request.id)
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try:
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self.client.delete(path)
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except kze.NoNodeError:
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pass
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def nodeRequestExists(self, node_request):
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'''
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See if a NodeRequest exists in ZooKeeper.
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:param NodeRequest node_request: A NodeRequest to verify.
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:returns: True if the request exists, False otherwise.
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'''
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path = '%s/%s' % (self.REQUEST_ROOT, node_request.id)
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if self.client.exists(path):
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return True
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return False
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def storeNodeRequest(self, node_request):
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'''Store the node request.
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The request is expected to already exist and is updated in its
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entirety.
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:param NodeRequest node_request: The request to update.
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'''
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path = '%s/%s' % (self.REQUEST_ROOT, node_request.id)
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self.client.set(path, self._dictToStr(node_request.toDict()))
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def updateNodeRequest(self, node_request, data=None):
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'''Refresh an existing node request.
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:param NodeRequest node_request: The request to update.
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:param dict data: The data to use; query ZK if absent.
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'''
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if data is None:
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path = '%s/%s' % (self.REQUEST_ROOT, node_request.id)
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data, stat = self.client.get(path)
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data = self._strToDict(data)
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request_nodes = list(node_request.nodeset.getNodes())
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for i, nodeid in enumerate(data.get('nodes', [])):
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request_nodes[i].id = nodeid
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self.updateNode(request_nodes[i])
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node_request.updateFromDict(data)
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def storeNode(self, node):
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'''Store the node.
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The node is expected to already exist and is updated in its
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entirety.
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:param Node node: The node to update.
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'''
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path = '%s/%s' % (self.NODE_ROOT, node.id)
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self.client.set(path, self._dictToStr(node.toDict()))
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def updateNode(self, node):
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'''Refresh an existing node.
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:param Node node: The node to update.
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'''
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node_path = '%s/%s' % (self.NODE_ROOT, node.id)
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node_data, node_stat = self.client.get(node_path)
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node_data = self._strToDict(node_data)
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node.updateFromDict(node_data)
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def lockNode(self, node, blocking=True, timeout=None):
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'''
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Lock a node.
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This should be called as soon as a request is fulfilled and
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the lock held for as long as the node is in-use. It can be
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used by nodepool to detect if Zuul has gone offline and the
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node should be reclaimed.
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:param Node node: The node which should be locked.
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'''
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lock_path = '%s/%s/lock' % (self.NODE_ROOT, node.id)
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try:
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lock = Lock(self.client, lock_path)
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have_lock = lock.acquire(blocking, timeout)
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except kze.LockTimeout:
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raise LockException(
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"Timeout trying to acquire lock %s" % lock_path)
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# If we aren't blocking, it's possible we didn't get the lock
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# because someone else has it.
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if not have_lock:
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raise LockException("Did not get lock on %s" % lock_path)
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node.lock = lock
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def unlockNode(self, node):
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'''
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Unlock a node.
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The node must already have been locked.
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:param Node node: The node which should be unlocked.
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'''
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if node.lock is None:
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raise LockException("Node %s does not hold a lock" % (node,))
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node.lock.release()
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node.lock = None
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def lockNodeRequest(self, request, blocking=True, timeout=None):
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'''
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Lock a node request.
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This will set the `lock` attribute of the request object when the
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lock is successfully acquired.
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:param NodeRequest request: The request to lock.
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:param bool blocking: Whether or not to block on trying to
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acquire the lock
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:param int timeout: When blocking, how long to wait for the lock
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to get acquired. None, the default, waits forever.
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:raises: TimeoutException if we failed to acquire the lock when
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blocking with a timeout. ZKLockException if we are not blocking
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and could not get the lock, or a lock is already held.
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'''
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path = "%s/%s" % (self.REQUEST_LOCK_ROOT, request.id)
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try:
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lock = Lock(self.client, path)
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have_lock = lock.acquire(blocking, timeout)
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except kze.LockTimeout:
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raise LockException(
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"Timeout trying to acquire lock %s" % path)
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except kze.NoNodeError:
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have_lock = False
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self.log.error("Request not found for locking: %s", request)
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# If we aren't blocking, it's possible we didn't get the lock
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# because someone else has it.
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if not have_lock:
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raise LockException("Did not get lock on %s" % path)
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request.lock = lock
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self.updateNodeRequest(request)
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def unlockNodeRequest(self, request):
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'''
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Unlock a node request.
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The request must already have been locked.
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:param NodeRequest request: The request to unlock.
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:raises: ZKLockException if the request is not currently locked.
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'''
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if request.lock is None:
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raise LockException(
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"Request %s does not hold a lock" % request)
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request.lock.release()
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request.lock = None
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def heldNodeCount(self, autohold_key):
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'''
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Count the number of nodes being held for the given tenant/project/job.
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:param set autohold_key: A set with the tenant/project/job names.
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'''
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identifier = " ".join(autohold_key)
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try:
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nodes = self.client.get_children(self.NODE_ROOT)
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except kze.NoNodeError:
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return 0
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count = 0
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for nodeid in nodes:
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node_path = '%s/%s' % (self.NODE_ROOT, nodeid)
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try:
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node_data, node_stat = self.client.get(node_path)
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except kze.NoNodeError:
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# Node got removed on us. Just ignore.
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continue
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if not node_data:
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self.log.warning("Node ID %s has no data", nodeid)
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continue
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node_data = self._strToDict(node_data)
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if (node_data['state'] == zuul.model.STATE_HOLD and
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node_data.get('hold_job') == identifier):
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count += 1
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return count
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# Copy of nodepool/zk.py begins here
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NODE_ROOT = "/nodepool/nodes"
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LAUNCHER_ROOT = "/nodepool/launchers"
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def _bytesToDict(self, data):
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return json.loads(data.decode('utf8'))
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def _launcherPath(self, launcher):
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return "%s/%s" % (self.LAUNCHER_ROOT, launcher)
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def _nodePath(self, node):
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return "%s/%s" % (self.NODE_ROOT, node)
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def getRegisteredLaunchers(self):
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'''
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Get a list of all launchers that have registered with ZooKeeper.
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:returns: A list of Launcher objects, or empty list if none are found.
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'''
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try:
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launcher_ids = self.client.get_children(self.LAUNCHER_ROOT)
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except kze.NoNodeError:
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return []
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objs = []
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for launcher in launcher_ids:
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path = self._launcherPath(launcher)
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try:
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data, _ = self.client.get(path)
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except kze.NoNodeError:
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# launcher disappeared
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continue
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objs.append(Launcher.fromDict(self._bytesToDict(data)))
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return objs
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def getNodes(self):
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'''
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Get the current list of all nodes.
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:returns: A list of nodes.
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'''
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try:
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return self.client.get_children(self.NODE_ROOT)
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except kze.NoNodeError:
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return []
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def getNode(self, node):
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'''
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Get the data for a specific node.
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:param str node: The node ID.
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:returns: The node data, or None if the node was not found.
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'''
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path = self._nodePath(node)
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try:
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data, stat = self.client.get(path)
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except kze.NoNodeError:
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return None
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if not data:
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return None
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d = self._bytesToDict(data)
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d['id'] = node
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return d
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def nodeIterator(self):
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'''
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Utility generator method for iterating through all nodes.
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'''
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for node_id in self.getNodes():
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node = self.getNode(node_id)
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if node:
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yield node
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class Launcher():
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'''
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Class to describe a nodepool launcher.
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'''
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def __init__(self):
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self.id = None
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self._supported_labels = set()
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def __eq__(self, other):
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if isinstance(other, Launcher):
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return (self.id == other.id and
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self.supported_labels == other.supported_labels)
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else:
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return False
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@property
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def supported_labels(self):
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return self._supported_labels
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@supported_labels.setter
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def supported_labels(self, value):
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if not isinstance(value, set):
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raise TypeError("'supported_labels' attribute must be a set")
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self._supported_labels = value
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@staticmethod
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def fromDict(d):
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obj = Launcher()
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obj.id = d.get('id')
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obj.supported_labels = set(d.get('supported_labels', []))
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return obj
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