74 lines
2.6 KiB
Python
74 lines
2.6 KiB
Python
# Copyright 2021, 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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import logging
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from contextlib import contextmanager
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from ops.model import BlockedStatus
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logger = logging.getLogger(__name__)
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class GuardException(Exception):
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pass
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class BlockedException(Exception):
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pass
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@contextmanager
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def guard(charm: 'CharmBase',
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section: str,
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handle_exception: bool = True,
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log_traceback: bool = True,
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**__):
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"""Context manager to handle errors and bailing out of an event/hook.
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The nature of Juju is that all the information may not be available to run
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a set of actions. This context manager allows a section of code to be
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'guarded' so that it can be bailed at any time.
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It also handles errors which can be interpreted as a Block rather than the
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charm going into error.
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:param charm: the charm class (so that unit status can be set)
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:param section: the name of the section (for debugging/info purposes)
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:handle_exception: whether to handle the exception to a BlockedStatus()
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:log_traceback: whether to log the traceback for debugging purposes.
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:raises: Exception if handle_exception is False
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"""
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logger.info("Entering guarded section: '%s'", section)
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try:
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yield
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logging.info("Completed guarded section fully: '%s'", section)
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except GuardException as e:
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logger.info("Guarded Section: Early exit from '%s' due to '%s'.",
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section, str(e))
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except BlockedException as e:
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logger.warning(
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"Charm is blocked in section '%s' due to '%s'", section, str(e))
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charm.unit.status = BlockedStatus(e.msg)
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except Exception as e:
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# something else went wrong
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if handle_exception:
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logging.error("Exception raised in secion '%s': %s",
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section, str(e))
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if log_traceback:
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import traceback
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logging.error(traceback.format_exc())
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charm.unit.status = BlockedStatus(
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"Error in charm (see logs): {}".format(str(e)))
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return
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raise
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