a85980f087
Break up the configure_charm method into distinct phases each with a dedicated method. This makes it much easier for a charm specialising this class to customise and individual phase without having to duplicate code. To enable this the configure_charm method has been adapted to use the guard function. This allows any method within the guard context manager to throw a guard exception to halt the configuration process and have the issue reflected in the units workload status. This is more flexable approach then the old method of having configuration steps return a boolean. Change-Id: I6b46bae1dc700f5e8b597374c660c0af9c069172
104 lines
3.0 KiB
Python
104 lines
3.0 KiB
Python
# Copyright 2023 Canonical Ltd.
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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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"""Helpers for controlling whether jobs should run.
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In general it is better for a command to be a noop if run when it is not
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needed but in some cases the commands are expensive or disruptive in which
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case these helpers can limit how frequently they are run.
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"""
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import logging
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import time
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from functools import (
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wraps,
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)
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from typing import (
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TYPE_CHECKING,
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)
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import ops.framework
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if TYPE_CHECKING:
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import ops_sunbeam.charm
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logger = logging.getLogger(__name__)
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def run_once_per_unit(label):
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"""Run once per instantiation of a unit.
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This is designed for commands which only need to be run once on each
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instantiation of a unit.
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Note: This decorator can only be used within a charm derived from
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ops_sunbeam.charm.OSBaseOperatorCharm.
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Example usage:
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class MyCharm(ops_sunbeam.charm.OSBaseOperatorCharm):
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...
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@run_once_per_unit('a2enmod')
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def enable_apache_module(self):
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check_call(['a2enmod', 'wsgi'])
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"""
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def wrap(f):
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@wraps(f)
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def wrapped_f(
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charm: "ops_sunbeam.charm.OSBaseOperatorCharm", *args, **kwargs
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):
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"""Run once decorator.
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:param charm: Instance of charm
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"""
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storage = LocalJobStorage(charm._state)
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if label in storage:
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logging.warning(
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f"Not running {label}, it has run previously for this unit"
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)
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else:
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logging.warning(
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f"Running {label}, it has not run on this unit before"
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)
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f(charm, *args, **kwargs)
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storage.add(label)
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return wrapped_f
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return wrap
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class LocalJobStorage:
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"""Class to store job info of jobs run on the local unit."""
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def __init__(self, storage: ops.framework.BoundStoredState):
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"""Setup job history storage."""
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self.storage = storage
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try:
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self.storage.run_once
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except AttributeError:
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self.storage.run_once = {}
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def get_labels(self):
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"""Return all job entries."""
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return self.storage.run_once
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def __contains__(self, key):
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"""Check if label is in list or run jobs."""
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return key in self.get_labels().keys()
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def add(self, key):
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"""Add the label of job that has run."""
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self.storage.run_once[key] = str(time.time())
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