138 lines
4.3 KiB
Python
138 lines
4.3 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) 2018-2020 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, either version 3 of the License, or
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# (at your option) any later version.
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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 uuid
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# Child list function
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def listchildren(zk_conn, key):
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children = zk_conn.get_children(key)
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return children
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# Key deletion function
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def deletekey(zk_conn, key, recursive=True):
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zk_conn.delete(key, recursive=recursive)
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# Data read function
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def readdata(zk_conn, key):
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data_raw = zk_conn.get(key)
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data = data_raw[0].decode('utf8')
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meta = data_raw[1]
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return data
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# Data write function
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def writedata(zk_conn, kv):
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# Start up a transaction
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zk_transaction = zk_conn.transaction()
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# Proceed one KV pair at a time
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for key in sorted(kv):
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data = kv[key]
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if not data:
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data = ''
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# Check if this key already exists or not
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if not zk_conn.exists(key):
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# We're creating a new key
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zk_transaction.create(key, str(data).encode('utf8'))
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else:
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# We're updating a key with version validation
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orig_data = zk_conn.get(key)
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version = orig_data[1].version
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# Set what we expect the new version to be
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new_version = version + 1
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# Update the data
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zk_transaction.set_data(key, str(data).encode('utf8'))
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# Set up the check
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try:
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zk_transaction.check(key, new_version)
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except TypeError:
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print('Zookeeper key "{}" does not match expected version'.format(key))
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return False
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# Commit the transaction
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try:
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zk_transaction.commit()
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return True
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except Exception:
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return False
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# Key rename function
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def renamekey(zk_conn, kv):
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# This one is not transactional because, inexplicably, transactions don't
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# support either the recursive delete or recursive create operations that
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# we need. Why? No explanation in the docs that I can find.
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# Proceed one KV pair at a time
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for key in sorted(kv):
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old_name = key
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new_name = kv[key]
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old_data = zk_conn.get(old_name)[0]
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# Find the children of old_name recursively
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child_keys = list()
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def get_children(key):
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children = zk_conn.get_children(key)
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if not children:
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child_keys.append(key)
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else:
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for ckey in children:
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get_children('{}/{}'.format(key, ckey))
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get_children(old_name)
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# Get the data out of each of the child keys
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child_data = dict()
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for ckey in child_keys:
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child_data[ckey] = zk_conn.get(ckey)[0]
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# Create the new parent key
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zk_conn.create(new_name, old_data, makepath=True)
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# For each child key, create the key and add the data
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for ckey in child_keys:
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new_ckey_name = ckey.replace(old_name, new_name)
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zk_conn.create(new_ckey_name, child_data[ckey], makepath=True)
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# Remove recursively the old key
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zk_conn.delete(old_name, recursive=True)
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# Write lock function
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def writelock(zk_conn, key):
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lock_id = str(uuid.uuid1())
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lock = zk_conn.WriteLock('{}'.format(key), lock_id)
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return lock
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# Read lock function
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def readlock(zk_conn, key):
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lock_id = str(uuid.uuid1())
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lock = zk_conn.ReadLock('{}'.format(key), lock_id)
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return lock
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# Exclusive lock function
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def exclusivelock(zk_conn, key):
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lock_id = str(uuid.uuid1())
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lock = zk_conn.Lock('{}'.format(key), lock_id)
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return lock
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