Add asyncio eventloop.
This commits introduces the asyncio event loop as well as the base abstract class to define watchers. It is in a very simple approach (it does not reschedule watchers if they fail) but it lets you to see the proposal of hierarchy in watchers as well as the methods that a watcher has to implement (see the pod module). Partial-Implements: blueprint kuryr-k8s-integration Co-Authored-By: Taku Fukushima <f.tac.mac@gmail.com> Co-Authored-By: Antoni Segura Puimedon Change-Id: I91975dd197213c1a6b0e171c1ae218a547722eeb
This commit is contained in:
Jaume Devesa
parent
a8a91ef38c
commit
82dce858cf
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@ -10,34 +10,51 @@
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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 asyncio
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import sys
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import time
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from kuryr.lib._i18n import _LI
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from oslo_log import log as logging
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from oslo_service import service
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from kuryr_kubernetes import config
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from kuryr_kubernetes.watchers import pod
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LOG = logging.getLogger(__name__)
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class KuryrK8sService(service.Service):
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"""Kuryr-Kubernetes base service.
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This class extends the oslo_service.service.Service class to provide an
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asynchronous event loop. It assumes that all the elements of the
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`_watchers` list has a method called `watch` (normally, implemented by the
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class `kuryr_kubernetes.watchers.base.AbstractBaseWatcher`).
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The event loop is the default used by asyncio (asyncio.SelectorEventLoop)
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"""
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def __init__(self):
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super(KuryrK8sService, self).__init__()
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self._event_loop = asyncio.new_event_loop()
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self._watchers = [
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pod.PodWatcher
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]
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def start(self):
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# TODO(devvesa): Remove this line as soon as it does anything
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LOG.info(_LI("I am doing nothing"))
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LOG.info(_LI("Service '%(class_name)s' started"),
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{'class_name': self.__class__.__name__})
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for watcher in self._watchers:
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instance = watcher(self._event_loop)
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self._event_loop.create_task(instance.watch())
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try:
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while(True):
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time.sleep(5)
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# TODO(devvesa): Remove this line as soon as does anything
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LOG.info(_LI("Keep doing nothing"))
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finally:
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self._event_loop.run_forever()
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self._event_loop.close()
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except Exception:
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sys.exit(1)
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sys.exit(0)
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def wait(self):
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"""Waits for K8sController to complete."""
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@ -0,0 +1,22 @@
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# 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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from oslo_serialization import jsonutils
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def utf8_json_decoder(byte_data):
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"""Deserializes the bytes into UTF-8 encoded JSON.
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:param byte_data: The bytes to be converted into the UTF-8 encoded JSON.
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:returns: The UTF-8 encoded JSON represented by Python dictionary format.
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"""
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return jsonutils.loads(byte_data.decode('utf8'))
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@ -0,0 +1,123 @@
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# 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 abc
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import requests
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from kuryr.lib._i18n import _LE
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from oslo_log import log as logging
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from kuryr_kubernetes.aio import headers as aio_headers
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from kuryr_kubernetes.aio import methods as aio_methods
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from kuryr_kubernetes import config
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from kuryr_kubernetes import utils
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LOG = logging.getLogger(__name__)
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ADDED_EVENT = 'ADDED'
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DELETED_EVENT = 'DELETED'
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MODIFIED_EVENT = 'MODIFIED'
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class AbstractBaseWatcher(object):
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"""Base abstract watcher.
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This class implements the default interface for the KuryrK8sService task
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scheduler, which is the `watch` (no parameters) interface.
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It also define a serie of abstract methods that actual watchers have to
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implement in order to deal directly with events without worrying about
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connection and serialization details.
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These methods are:
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* get_endpoint(self): return a resource URL exposed on Kubernetes API
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as a string (such as "/api/v1/pods")
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* on_add/on_modify/on_delete: actions to do according to each event
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type.
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These methods have to follow the async/await python3.5 syntax
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"""
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def __init__(self, event_loop):
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self._event_loop = event_loop
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@abc.abstractmethod
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def get_api_endpoint(self):
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pass
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@property
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def api_endpoint(self):
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k8s_root = config.CONF.kubernetes.api_root
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return k8s_root + self.get_api_endpoint() + "?watch=true"
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async def _on_event(self, event): # flake8: noqa
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event_type = event['type']
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if event_type == ADDED_EVENT:
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await self.on_add(event)
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elif event_type == DELETED_EVENT:
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await self.on_delete(event)
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elif event_type == MODIFIED_EVENT:
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await self.on_modify(event)
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else:
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LOG.warning(_LW("Unhandled event type '%(event_type)s'"),
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{'event_type': event})
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@abc.abstractmethod
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async def on_add(self, event):
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pass
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@abc.abstractmethod
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async def on_modify(self, event):
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pass
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@abc.abstractmethod
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async def on_delete(self, event):
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pass
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async def watch(self):
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"""Watches the endpoint and calls the callback with its response.
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This is an endless task that keeps the event loop running forever
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"""
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response = await self._get_chunked_response()
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while True:
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content = await response.read_line()
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LOG.debug('Received new event from %(watcher)s:\n\n\t'
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'%(event)s.\n\n',
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{'watcher': self.__class__.__name__,
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'event': str(content)})
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await self._on_event(content)
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async def _get_chunked_response(self):
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"""Get the response from Kubernetes API."""
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response = await aio_methods.get(
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endpoint=self.api_endpoint,
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loop=self._event_loop,
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decoder=utils.utf8_json_decoder)
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status, reason, hdrs = await response.read_headers()
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if status != requests.codes.ok: # Function returns 200
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LOG.error(_LE('GET request to endpoint %(ep)s failed with '
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'status %(status)s and reason %(reason)s'),
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{'ep': endpoint, 'status': status, 'reason': reason})
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raise requests.exceptions.HTTPError('{}: {}. Endpoint {}'.format(
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status, reason, endpoint))
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if hdrs.get(aio_headers.TRANSFER_ENCODING) != 'chunked':
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LOG.error(_LE('watcher GET request to endpoint %(ep)s is not '
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'chunked. headers: %(hdrs)s'),
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{'ep': endpoint, 'hdrs': hdrs})
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raise IOError(_('Can only watch endpoints that returned chunked '
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'encoded transfers'))
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return response
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@ -0,0 +1,38 @@
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# 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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from kuryr.lib._i18n import _LI
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from oslo_log import log as logging
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from kuryr_kubernetes.watchers import base
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LOG = logging.getLogger(__name__)
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class PodWatcher(base.AbstractBaseWatcher):
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ENDPOINT = "/api/v1/pods"
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def __init__(self, event_loop):
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super().__init__(event_loop)
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def get_api_endpoint(self):
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return self.ENDPOINT
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async def on_add(self, event): # flake8: noqa
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LOG.info(_LI('Received an ADDED event on a Pod'))
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async def on_modify(self, event):
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LOG.info(_LI('Received a MODIFIED event on a Pod'))
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async def on_delete(self, event):
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LOG.info(_LI('Received a DELETED event on a Pod'))
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