314 lines
11 KiB
Python
314 lines
11 KiB
Python
# Copyright 2019, AT&T Intellectual Property
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import functools
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import time
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from datetime import datetime, timedelta
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from concurrent.futures import ThreadPoolExecutor
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from kubernetes import client
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from kubernetes.client.rest import ApiException
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from oslo_config import cfg
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from oslo_log import log as logging
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from armada.handlers.k8s import K8s
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from armada.handlers.helm import Helm
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CONF = cfg.CONF
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TIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
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# Lock configuration
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LOCK_GROUP = "armada.process"
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LOCK_VERSION = "v1"
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LOCK_NAMESPACE = "kube-system"
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LOCK_PLURAL = "locks"
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LOCK_SINGULAR = "lock"
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LOG = logging.getLogger(__name__)
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class LockException(Exception):
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pass
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def lock_and_thread(lock_name="lock"):
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"""This function creates a thread to execute the wrapped function after
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acquiring a lock. While the thread is still running, this function
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periodically updates the lock
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:param lock_name: name of the lock to create
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"""
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def lock_decorator(func):
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@functools.wraps(func)
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def func_wrapper(*args, **kwargs):
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bearer_token = None
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found_helm = False
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for arg in args:
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if type(arg) == Helm:
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bearer_token = arg.bearer_token
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found_helm = True
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# we did not find a Helm object to extract a bearer token from
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# log this to assist with potential debugging in the future
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if not found_helm:
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LOG.info(
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"no Helm object found in parameters of function "
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"decorated by lock_and_thread, this might create "
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"authentication issues in Kubernetes clusters with "
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"external auth backend")
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with Lock(lock_name, bearer_token=bearer_token) as lock:
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pool = ThreadPoolExecutor(1)
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future = pool.submit(func, *args, **kwargs)
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start = time.time()
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while not future.done():
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if time.time() - start > CONF.lock_update_interval:
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lock.update_lock()
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start = time.time()
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time.sleep(1)
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return future.result()
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return func_wrapper
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return lock_decorator
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class Lock:
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def __init__(self, lock_name, bearer_token=None, additional_data=None):
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"""Creates a lock with the specified name and data. When a lock with
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that name already exists then this will continuously attempt to acquire
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it until:
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* the attempt times out
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* the lock is gone this is able to acquire a new lock
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* the existing lock expires, in which case this will forcibly
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remove it and continue attempting to acquire the lock
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:param lock_name: name of the lock resource to be created, locks with
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different names can coexist and won't conflict with each other
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:param additional_data: dict of any additional data to be added to the
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lock's `data` section
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"""
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self.expire_time = CONF.lock_expiration
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self.timeout = CONF.lock_acquire_timeout
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self.acquire_delay = CONF.lock_acquire_delay
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self.lock_config = LockConfig(
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name=lock_name,
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bearer_token=bearer_token,
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additional_data=additional_data)
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def _test_lock_ownership(self):
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# If the uid of the current lock is the same as the one given when we
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# created the lock, then it must be the one created by this program
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lock = self.lock_config.get_lock()
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if lock:
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lock_uid = lock['metadata']['uid']
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current_uid = self.lock_config.metadata.get('uid', None)
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return current_uid == lock_uid
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# The lock must not exist
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return False
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def lock_age(self):
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lock = self.lock_config.get_lock()
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if lock:
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creation = lock['data']['lastUpdated']
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creation_time = datetime.strptime(creation, TIME_FORMAT)
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return datetime.utcnow() - creation_time
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# If no lock exists then 0 is returned so the lock is assuredly not old
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# enough to be expired
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return 0
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def acquire_lock(self):
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start = time.time()
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LOG.info("Acquiring lock")
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while (time.time() - start) < self.timeout:
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try:
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self.lock_config.create_lock()
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return True
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except ApiException as err:
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if err.status == 404:
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LOG.info(
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"Lock Custom Resource Definition not found, "
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"creating now")
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self.lock_config.create_definition()
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continue
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elif err.status == 409:
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# If the exception is 409 then there is already a lock, so
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# we should continue with the rest of the logic
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LOG.warn("There is already an existing lock")
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else:
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raise
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if self._test_lock_ownership():
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# If there is already a lock that was created by this thread
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# then we must have successfully acquired the lock
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return True
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else:
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# There is a lock but it was not created by this thread, which
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# means that the only way it should be removed is if the age
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# of the lock exceeds the expire time in order to avoid
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# removing another thread's lock while it is still working
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if self.lock_age() > timedelta(seconds=self.expire_time):
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LOG.info(
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"Lock has exceeded expiry time, removing so"
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"processing can continue")
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self.release_lock()
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continue
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LOG.debug("Sleeping before attempting to acquire lock again")
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time.sleep(self.acquire_delay)
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raise LockException("Unable to acquire lock before timeout")
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def release_lock(self):
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LOG.info("Releasing lock")
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return self.lock_config.delete_lock()
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def update_lock(self):
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LOG.debug("Updating lock")
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self.lock_config.replace_lock()
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def __enter__(self):
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self.acquire_lock()
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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self.release_lock()
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return False
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class LockConfig:
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def __init__(self, name, bearer_token=None, additional_data=None):
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self.name = name
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data = additional_data or dict()
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self.full_name = "{}.{}.{}".format(LOCK_PLURAL, LOCK_GROUP, self.name)
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self.metadata = {'name': self.full_name}
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self.body = {
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'kind': "Resource",
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'apiVersion': "{}/{}".format(LOCK_GROUP, LOCK_VERSION),
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'metadata': self.metadata,
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'data': data
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}
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self.delete_options = {}
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self.k8s = K8s(bearer_token=bearer_token)
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def create_lock(self):
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""" Creates the Lock custom resource object
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:return: the Lock custom resource object
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:rtype: object
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"""
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self.body['data']['lastUpdated'] = \
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datetime.utcnow().strftime(TIME_FORMAT)
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lock = self.k8s.create_custom_resource(
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group=LOCK_GROUP,
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version=LOCK_VERSION,
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namespace=LOCK_NAMESPACE,
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plural=LOCK_PLURAL,
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body=self.body)
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self.metadata = lock.get('metadata', self.metadata)
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return lock
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def get_lock(self):
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"""Retrieves the Lock custom resource object
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:return: the Lock custom resource object
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:rtype: object
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"""
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try:
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return self.k8s.read_custom_resource(
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group=LOCK_GROUP,
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version=LOCK_VERSION,
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namespace=LOCK_NAMESPACE,
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plural=LOCK_PLURAL,
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name=self.full_name)
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except ApiException as err:
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if err.status == 404:
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return None
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raise
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def delete_lock(self):
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"""Deletes the Lock custom resource
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:return: whether it was successfully deleted
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:rtype: bool
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"""
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try:
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self.k8s.delete_custom_resource(
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group=LOCK_GROUP,
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version=LOCK_VERSION,
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namespace=LOCK_NAMESPACE,
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plural=LOCK_PLURAL,
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name=self.full_name,
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body=self.delete_options)
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return True
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except ApiException as err:
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# If it returns 404 then something else deleted it
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if err.status == 404:
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return True
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raise
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def replace_lock(self):
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"""Updates the Lock custom resource object with a new lastUpdated time
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:return: the Lock custom resource object
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:rtype: object
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"""
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self.body['metadata']['resourceVersion'] = \
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self.metadata['resourceVersion']
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self.body['data']['lastUpdated'] = \
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datetime.utcnow().strftime(TIME_FORMAT)
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lock = self.k8s.replace_custom_resource(
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group=LOCK_GROUP,
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version=LOCK_VERSION,
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namespace=LOCK_NAMESPACE,
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plural=LOCK_PLURAL,
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name=self.full_name,
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body=self.body)
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self.metadata = lock.get('metadata', self.metadata)
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return lock
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def create_definition(self):
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names = client.V1CustomResourceDefinitionNames(
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kind="Resource", plural=LOCK_PLURAL, singular=LOCK_SINGULAR)
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metadata = client.V1ObjectMeta(
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name="{}.{}".format(LOCK_PLURAL, LOCK_GROUP),
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resource_version=LOCK_VERSION)
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spec = client.V1CustomResourceDefinitionSpec(
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group=LOCK_GROUP,
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names=names,
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scope="Namespaced",
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versions=[
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{
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"name": LOCK_VERSION,
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"schema": {
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"openAPIV3Schema": {
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"type": "object",
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"x-kubernetes-preserve-unknown-fields": True
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}
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},
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"served": True,
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"storage": True,
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}
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])
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crd = client.V1CustomResourceDefinition(
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spec=spec, metadata=metadata, kind="CustomResourceDefinition")
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try:
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self.k8s.create_custom_resource_definition(crd)
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except ApiException as err:
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# If a 409 is received then the definition already exists
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if err.status != 409:
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raise
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