Joshua M. Boniface
126f0742cd
Adds a new class, ZKSchema, to handle schema management in Zookeeper in an automated and consistent way. This should solve several issues: 1. Pain in managing changes to ZK keys 2. Pain in handling those changes during live upgrades 3. Simplifying the codebase to remove hardcoded ZK paths The current master schema for PVC 0.9.19 is committed as version 0. Addresses #129
718 lines
23 KiB
Python
718 lines
23 KiB
Python
#!/usr/bin/env python3
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# zkhandler.py - Secure versioned ZooKeeper updates
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# Part of the Parallel Virtual Cluster (PVC) system
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#
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# Copyright (C) 2018-2021 Joshua M. Boniface <joshua@boniface.me>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, version 3.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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#
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###############################################################################
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import os
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import time
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import uuid
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import json
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from functools import wraps
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from kazoo.client import KazooClient, KazooState
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from kazoo.exceptions import NoNodeError
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#
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# Function decorators
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#
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class ZKConnection(object):
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"""
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Decorates a function with a Zookeeper connection before and after the main call.
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The decorated function must accept the `zkhandler` argument as its first argument, and
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then use this to access the connection.
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"""
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def __init__(self, config):
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self.config = config
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def __call__(self, function):
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if not callable(function):
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return
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@wraps(function)
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def connection(*args, **kwargs):
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zkhandler = ZKHandler(self.config)
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zkhandler.connect()
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ret = function(zkhandler, *args, **kwargs)
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zkhandler.disconnect()
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del zkhandler
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return ret
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return connection
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#
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# Exceptions
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#
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class ZKConnectionException(Exception):
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"""
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A exception when connecting to the cluster
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"""
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def __init__(self, zkhandler, error=None):
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if error is not None:
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self.message = "Failed to connect to Zookeeper at {}: {}".format(zkhandler.coordinators(), error)
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else:
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self.message = "Failed to connect to Zookeeper at {}".format(zkhandler.coordinators())
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zkhandler.disconnect()
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def __str__(self):
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return str(self.message)
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#
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# Handler class
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#
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class ZKHandler(object):
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def __init__(self, config, logger=None):
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"""
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Initialize an instance of the ZKHandler class with config
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A zk_conn object will be created but not started
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"""
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self.encoding = 'utf8'
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self.coordinators = config['coordinators']
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self.logger = logger
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self.zk_conn = KazooClient(hosts=self.coordinators)
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#
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# Class meta-functions
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#
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def coordinators(self):
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return str(self.coordinators)
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def log(self, message, state=''):
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if self.logger is not None:
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self.logger.out(message, state)
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else:
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print(message)
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#
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# State/connection management
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#
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def listener(self, state):
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if state == KazooState.CONNECTED:
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self.log('Connection to Zookeeper started', state='o')
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else:
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self.log('Connection to Zookeeper lost', state='w')
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while True:
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time.sleep(0.5)
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_zk_conn = KazooClient(hosts=self.coordinators)
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try:
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_zk_conn.start()
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except Exception:
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del _zk_conn
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continue
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self.zk_conn = _zk_conn
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self.zk_conn.add_listener(self.listener)
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break
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def connect(self, persistent=False):
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"""
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Start the zk_conn object and connect to the cluster
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"""
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try:
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self.zk_conn.start()
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if persistent:
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self.zk_conn.add_listener(self.listener)
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except Exception as e:
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raise ZKConnectionException(self, e)
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def disconnect(self):
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"""
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Stop and close the zk_conn object and disconnect from the cluster
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The class instance may be reused later (avoids persistent connections)
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"""
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self.zk_conn.stop()
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self.zk_conn.close()
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#
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# Key Actions
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#
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def exists(self, key):
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"""
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Check if a key exists
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"""
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stat = self.zk_conn.exists(key)
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if stat:
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return True
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else:
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return False
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def read(self, key):
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"""
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Read data from a key
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"""
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return self.zk_conn.get(key)[0].decode(self.encoding)
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def write(self, kvpairs):
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"""
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Create or update one or more keys' data
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"""
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if type(kvpairs) is not list:
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self.log("ZKHandler error: Key-value sequence is not a list", state='e')
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return False
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transaction = self.zk_conn.transaction()
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for kvpair in (kvpairs):
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if type(kvpair) is not tuple:
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self.log("ZKHandler error: Key-value pair '{}' is not a tuple".format(kvpair), state='e')
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return False
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key = kvpair[0]
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value = kvpair[1]
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if not self.exists(key):
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# Creating a new key
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transaction.create(key, str(value).encode(self.encoding))
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else:
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# Updating an existing key
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data = self.zk_conn.get(key)
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version = data[1].version
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# Validate the expected version after the execution
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new_version = version + 1
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# Update the data
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transaction.set_data(key, str(value).encode(self.encoding))
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# Check the data
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try:
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transaction.check(key, new_version)
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except TypeError:
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self.log("ZKHandler error: Key '{}' does not match expected version".format(key), state='e')
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return False
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try:
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transaction.commit()
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return True
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except Exception as e:
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self.log("ZKHandler error: Failed to commit transaction: {}".format(e), state='e')
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return False
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def delete(self, keys, recursive=True):
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"""
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Delete a key or list of keys (defaults to recursive)
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"""
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if type(keys) is not list:
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keys = [keys]
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for key in keys:
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if self.exists(key):
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try:
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self.zk_conn.delete(key, recursive=recursive)
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except Exception as e:
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self.log("ZKHandler error: Failed to delete key {}: {}".format(key, e), state='e')
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return False
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return True
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def children(self, key):
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"""
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Lists all children of a key
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"""
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return self.zk_conn.get_children(key)
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def rename(self, kkpairs):
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"""
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Rename one or more keys to a new value
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"""
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if type(kkpairs) is not list:
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self.log("ZKHandler error: Key-key sequence is not a list", state='e')
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return False
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transaction = self.zk_conn.transaction()
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def rename_element(transaction, source_key, destnation_key):
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data = self.zk_conn.get(source_key)[0]
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transaction.create(destination_key, data)
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if self.children(source_key):
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for child_key in self.children(source_key):
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child_source_key = "{}/{}".format(source_key, child_key)
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child_destination_key = "{}/{}".format(destination_key, child_key)
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rename_element(transaction, child_source_key, child_destination_key)
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transaction.delete(source_key)
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for kkpair in (kkpairs):
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if type(kkpair) is not tuple:
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self.log("ZKHandler error: Key-key pair '{}' is not a tuple".format(kkpair), state='e')
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return False
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source_key = kkpair[0]
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destination_key = kkpair[1]
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if not self.exists(source_key):
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self.log("ZKHander error: Source key '{}' does not exist".format(source_key), state='e')
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return False
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if self.exists(destination_key):
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self.log("ZKHander error: Destination key '{}' already exists".format(destination_key), state='e')
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return False
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rename_element(transaction, source_key, destination_key)
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try:
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transaction.commit()
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return True
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except Exception as e:
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self.log("ZKHandler error: Failed to commit transaction: {}".format(e), state='e')
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return False
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#
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# Lock actions
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#
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def readlock(self, key):
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"""
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Acquires a read lock on a key
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"""
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count = 1
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lock = None
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while True:
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try:
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lock_id = str(uuid.uuid1())
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lock = self.zk_conn.ReadLock(key, lock_id)
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break
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except Exception as e:
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if count > 5:
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self.log("ZKHandler warning: Failed to acquire read lock after 5 tries: {}".format(e), state='e')
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break
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else:
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time.sleep(0.5)
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count += 1
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continue
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return lock
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def writelock(self, key):
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"""
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Acquires a write lock on a key
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"""
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count = 1
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lock = None
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while True:
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try:
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lock_id = str(uuid.uuid1())
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lock = self.zk_conn.WriteLock(key, lock_id)
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break
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except Exception as e:
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if count > 5:
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self.log("ZKHandler warning: Failed to acquire write lock after 5 tries: {}".format(e), state='e')
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break
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else:
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time.sleep(0.5)
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count += 1
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continue
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return lock
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def exclusivelock(self, key):
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"""
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Acquires an exclusive lock on a key
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"""
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count = 1
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lock = None
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while True:
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try:
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lock_id = str(uuid.uuid1())
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lock = self.zk_conn.Lock(key, lock_id)
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break
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except Exception as e:
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if count > 5:
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self.log("ZKHandler warning: Failed to acquire exclusive lock after 5 tries: {}".format(e), state='e')
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break
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else:
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time.sleep(0.5)
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count += 1
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continue
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return lock
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#
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# Schema classes
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#
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class ZKSchema(object):
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# Current version
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_version = 0
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# Root for doing nested keys
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_schema_root = ''
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# Primary schema definition for the current version
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_schema = {
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'version': f'{_version}',
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'root': f'{_schema_root}',
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# Base schema defining core keys; this is all that is initialized on cluster init()
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'base': {
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'schema': f'{_schema_root}/schema',
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'schema.version': f'{_schema_root}/schema/version',
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'config': f'{_schema_root}/config',
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'config.maintenance': f'{_schema_root}/config/maintenance',
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'config.primary_node': f'{_schema_root}/config/primary_node',
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'config.upstream_ip': f'{_schema_root}/config/upstream_ip',
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'config.migration_target_selector': f'{_schema_root}/config/migration_target_selector',
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'lock': f'{_schema_root}/locks',
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'lock.primary_node': f'{_schema_root}/locks/primary_node',
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'lock.flush_lock': f'{_schema_root}/locks/flush_lock',
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'lock.domain_migrate': f'{_schema_root}/locks/domain_migrate',
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'cmd': f'{_schema_root}/cmd',
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'cmd.nodes': f'{_schema_root}/cmd/nodes',
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'cmd.domains': f'{_schema_root}/cmd/domains',
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'cmd.ceph': f'{_schema_root}/cmd/ceph',
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'node': f'{_schema_root}/nodes',
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'domain': f'{_schema_root}/domains',
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'network': f'{_schema_root}/networks',
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'storage': f'{_schema_root}/ceph',
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'storage.util': f'{_schema_root}/ceph/util',
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'osd': f'{_schema_root}/ceph/osds',
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'pool': f'{_schema_root}/ceph/pools',
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'volume': f'{_schema_root}/ceph/volumes',
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'snapshot': f'{_schema_root}/ceph/snapshots',
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},
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# The schema of an individual node entry (/nodes/{node_name})
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'node': {
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'keepalive': '/keepalive',
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'mode': '/daemonmode',
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'staticdata': '/static_data',
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'data.kernel': '/oskernelversion',
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'data.os': '/ostype',
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'data.arch': '/osarch',
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'counts.provisioned_domains': '/domainscount',
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'counts.running_domains': '/runningdomains',
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'counts.networks': '/networkscount',
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'state.daemon': '/daemonstate',
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'state.router': '/routerstate',
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'state.domain': '/domainstate',
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'vcpu.total': '/vcputotal',
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'vcpu.allocated': '/vcpualloc',
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'memory.total': '/memtotal',
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'memory.used': '/memused',
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'memory.free': '/memfree',
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'memory.allocated': '/memalloc',
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'memory.provisioned': '/memprov',
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'ipmi.hostname': '/ipmihostname',
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'ipmi.username': '/ipmiusername',
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'ipmi.password': '/ipmipassword'
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},
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# The schema of an individual domain entry (/domains/{domain_uuid})
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'domain': {
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'name': '', # The root key
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'xml': '/xml',
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'state': '/state',
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'profile': '/profile',
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'stats': '/stats',
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'node': '/node',
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'last_node': '/lastnode',
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'failed_reason': '/failedreason',
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'console.log': '/consolelog',
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'console.vnc': '/vnc',
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'meta.autostart': '/node_autostart',
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'meta.migrate_method': '/migration_method',
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'meta.node_selector': '/node_selector',
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'meta.node_limit': '/node_limit'
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},
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# The schema of an individual network entry (/networks/{vni})
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'network': {
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'type': '/nettype',
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'rules': '/firewall_rules',
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'nameservers': '/name_servers',
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'domain': '/domain',
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'ip4.gateway': '/ip4_gateway',
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'ip4.network': '/ip4_network',
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'ip4.dhcp': '/dhcp4_flag',
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'ip4.reservations': '/dhcp4_reservations',
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'ip4.dhcp_start': '/dhcp4_start',
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'ip4.dhcp_end': '/dhcp4_end',
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'ip6.gateway': '/ip6_gateway',
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'ip6.network': '/ip6_network',
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'ip6.dhcp': '/dhcp6_flag'
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},
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# The schema of an individual OSD entry (/ceph/osds/{osd_id})
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'osd': {
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'node': '/node',
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'device': '/device',
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'stats': '/stats'
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},
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# The schema of an individual pool entry (/ceph/pools/{pool_name})
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'pool': {
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'pgs': '/pgs',
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'stats': '/stats'
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},
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# The schema of an individual volume entry (/ceph/volumes/{pool_name}/{volume_name})
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'volume': {
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'stats': '/stats'
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},
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# The schema of an individual snapshot entry (/ceph/volumes/{pool_name}/{volume_name}/{snapshot_name})
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'snapshot': {
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'stats': '/stats'
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}
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}
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# Properties
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@property
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def schema_root(self):
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return self._schema_root
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@schema_root.setter
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def schema_root(self, schema_root):
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self._schema_root = schema_root
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@property
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def version(self):
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return int(self._version)
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@version.setter
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def version(self, version):
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self._version = int(version)
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@property
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def schema(self):
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return self._schema
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@schema.setter
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def schema(self, schema):
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self._schema = schema
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def __init__(self):
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pass
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def __repr__(self):
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return f'ZKSchema({self.version})'
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def __lt__(self, other):
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if self.version < other.version:
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return True
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else:
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return False
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def __le__(self, other):
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if self.version <= other.version:
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return True
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else:
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return False
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def __gt__(self, other):
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if self.version > other.version:
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return True
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else:
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return False
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def __ge__(self, other):
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if self.version >= other.version:
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return True
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else:
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return False
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def __eq__(self, other):
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if self.version == other.version:
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return True
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else:
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return False
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# Load the schema of a given version from a file
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def load(self, version):
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print(f'Loading schema version {version}')
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with open(f'daemon_lib/migrations/versions/{version}.json', 'r') as sfh:
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self.schema = json.load(sfh)
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self.version = self.schema.get('version')
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# Get key paths
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def path(self, ipath, item=None):
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itype, *ipath = ipath.split('.')
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if item is None:
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return self.schema.get(itype).get('.'.join(ipath))
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else:
|
|
base_path = self.schema.get('base').get(itype)
|
|
sub_path = self.schema.get(itype).get('.'.join(ipath))
|
|
return f'{base_path}/{item}{sub_path}'
|
|
|
|
# Get keys of a schema location
|
|
def keys(self, itype=None):
|
|
if itype is None:
|
|
return list(self.schema.get('base').keys())
|
|
else:
|
|
return list(self.schema.get(itype).keys())
|
|
|
|
# Get the active version of a cluster's schema
|
|
def get_version(self, zkhandler):
|
|
try:
|
|
current_version = zkhandler.read(self.path('base.schema.version'))
|
|
except NoNodeError:
|
|
current_version = 0
|
|
return current_version
|
|
|
|
# Validate an active schema against a Zookeeper cluster
|
|
def validate(self, zkhandler, path='base'):
|
|
for key in self.keys(path):
|
|
if not zkhandler.exists(self.path(path + '.' + key)):
|
|
print(f"Key not found: {self.path(key)}")
|
|
return False
|
|
return True
|
|
|
|
# Apply the current schema to the cluster
|
|
def apply(self, zkhandler, path='base'):
|
|
for key in self.keys(path):
|
|
if not zkhandler.exists(self.path(path + '.' + key)):
|
|
zkhandler.write([
|
|
(self.path(path + '.' + key), '')
|
|
])
|
|
|
|
zkhandler.write([
|
|
(self.path('base.schema.version'), self.version)
|
|
])
|
|
|
|
# Migrate key diffs
|
|
def run_migrate(self, zkhandler, changes):
|
|
diff_add = changes['add']
|
|
diff_remove = changes['remove']
|
|
diff_rename = changes['rename']
|
|
add_tasks = list()
|
|
for key in diff_add.keys():
|
|
add_tasks.append((diff_add[key], ''))
|
|
remove_tasks = list()
|
|
for key in diff_remove.keys():
|
|
remove_tasks.append(diff_remove[key])
|
|
rename_tasks = list()
|
|
for key in diff_rename.keys():
|
|
rename_tasks.append((diff_rename[key]['from'], diff_rename[key]['to']))
|
|
|
|
print(add_tasks)
|
|
print(remove_tasks)
|
|
print(rename_tasks)
|
|
zkhandler.write(add_tasks)
|
|
zkhandler.delete(remove_tasks)
|
|
zkhandler.rename(rename_tasks)
|
|
|
|
# Migrate from older to newer schema
|
|
def migrate(self, zkhandler, new_version):
|
|
# Determine the versions in between
|
|
versions = ZKSchema.find_all(start=self.version, end=new_version)
|
|
print(versions)
|
|
|
|
for version in versions:
|
|
# Create a new schema at that version
|
|
zkschema_new = ZKSchema()
|
|
zkschema_new.load(version)
|
|
# Get a list of changes
|
|
changes = ZKSchema.key_diff(self, zkschema_new)
|
|
print(changes)
|
|
# Apply those changes
|
|
self.run_migrate(zkhandler, changes)
|
|
# Update the schema version key
|
|
zkhandler.write([
|
|
(self.key('base.schema.version'), zkschema_new.version)
|
|
])
|
|
|
|
# Rollback from newer to older schema
|
|
def rollback(self, zkhandler, old_version):
|
|
# Determine the versions in between
|
|
versions = ZKSchema.find_all(start=old_version - 1, end=self.version - 1)
|
|
versions.reverse()
|
|
print(versions)
|
|
|
|
for version in versions:
|
|
# Create a new schema at that version
|
|
zkschema_old = ZKSchema()
|
|
zkschema_old.load(version)
|
|
# Get a list of changes
|
|
changes = ZKSchema.key_diff(self, zkschema_old)
|
|
print(changes)
|
|
# Apply those changes
|
|
self.run_migrate(zkhandler, changes)
|
|
# Update the schema version key
|
|
zkhandler.write([
|
|
(self.key('base.schema.version'), zkschema_old.version)
|
|
])
|
|
|
|
@classmethod
|
|
def key_diff(cls, schema_a, schema_b):
|
|
# schema_a = current
|
|
# schema_b = new
|
|
|
|
diff_add = dict()
|
|
diff_remove = dict()
|
|
diff_rename = dict()
|
|
|
|
# Parse through each core element
|
|
for elem in ['base', 'node', 'domain', 'network', 'osd', 'pool', 'volume', 'snapshot']:
|
|
set_a = set(schema_a.keys(elem))
|
|
set_b = set(schema_b.keys(elem))
|
|
diff_keys = set_a ^ set_b
|
|
|
|
for item in diff_keys:
|
|
elem_item = elem + '.' + item
|
|
if item not in schema_a.keys(elem) and item in schema_b.keys(elem):
|
|
diff_add[elem_item] = schema_b.path(elem_item)
|
|
if item in schema_a.keys(elem) and item not in schema_b.keys(elem):
|
|
diff_remove[elem_item] = schema_a.path(elem_item)
|
|
|
|
for item in set_b:
|
|
elem_item = elem + '.' + item
|
|
if schema_a.path(elem_item) is not None and \
|
|
schema_b.path(elem_item) is not None and \
|
|
schema_a.path(elem_item) != schema_b.path(elem_item):
|
|
diff_rename[elem_item] = {'from': schema_a.path(elem_item), 'to': schema_b.path(elem_item)}
|
|
|
|
return {'add': diff_add, 'remove': diff_remove, 'rename': diff_rename}
|
|
|
|
# Load in the schemal of the current cluster
|
|
@classmethod
|
|
def load_current(cls, zkhandler):
|
|
new_instance = cls()
|
|
version = new_instance.get_version(zkhandler)
|
|
new_instance.load(version)
|
|
return new_instance
|
|
|
|
# Write the latest schema to a file
|
|
@classmethod
|
|
def write(cls):
|
|
schema_file = 'daemon_lib/migrations/versions/{}.json'.format(cls._version)
|
|
with open(schema_file, 'w') as sfh:
|
|
json.dump(cls._schema, sfh)
|
|
|
|
# Static methods for reading information from the files
|
|
@staticmethod
|
|
def find_all(start=0, end=None):
|
|
versions = list()
|
|
for version in os.listdir('daemon_lib/migrations/versions'):
|
|
sequence_id = int(version.split('.')[0])
|
|
if end is None:
|
|
if sequence_id > start:
|
|
versions.append(sequence_id)
|
|
else:
|
|
if sequence_id > start and sequence_id <= end:
|
|
versions.append(sequence_id)
|
|
if len(versions) > 0:
|
|
return versions
|
|
else:
|
|
return None
|