99e69fdc9d
When the setup of relation handlers throws an ops sunbeam status exception, the charm is put to error while this is a supported patterns for developping charms. The reason is that the exception is not thrown from within a guard. But it is reasonable, for example, for `OSBaseOperatorAPICharm.internal_url` to raise a WaitingExceptionError instead of returning None. Change-Id: Ide137421308733784b6aca7e247eb3e13485d2ff Signed-off-by: Guillaume Boutry <guillaume.boutry@canonical.com>
144 lines
4.0 KiB
Python
144 lines
4.0 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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"""Module to handle errors and bailing out of an event/hook."""
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import logging
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import typing
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from contextlib import (
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contextmanager,
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)
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from ops import (
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ActiveStatus,
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BlockedStatus,
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MaintenanceStatus,
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StatusBase,
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WaitingStatus,
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)
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if typing.TYPE_CHECKING:
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from ops_sunbeam.charm import (
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OSBaseOperatorCharm,
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)
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logger = logging.getLogger(__name__)
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class GuardExceptionError(Exception):
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"""GuardException."""
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pass
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class BaseStatusExceptionError(Exception):
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"""Charm is blocked."""
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status_type: type[StatusBase] = ActiveStatus
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def __init__(self, msg: str):
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super().__init__(msg)
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self.msg = msg
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def to_status(self):
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"""Convert the exception to an ops status."""
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return self.status_type(self.msg)
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class BlockedExceptionError(BaseStatusExceptionError):
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"""Charm is blocked."""
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status_type = BlockedStatus
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class MaintenanceExceptionError(BaseStatusExceptionError):
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"""Charm is performing maintenance."""
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status_type = MaintenanceStatus
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class WaitingExceptionError(BaseStatusExceptionError):
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"""Charm is waiting."""
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status_type = WaitingStatus
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@contextmanager
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def guard(
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charm: "OSBaseOperatorCharm",
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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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) -> typing.Generator:
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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 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 GuardExceptionError as e:
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logger.info(
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"Guarded Section: Early exit from '%s' due to '%s'.",
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section,
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str(e),
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)
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except BlockedExceptionError 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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)
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charm.status.set(e.to_status())
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except WaitingExceptionError as e:
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logger.warning(
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"Charm is waiting in section '%s' due to '%s'", section, str(e)
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)
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charm.status.set(e.to_status())
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except MaintenanceExceptionError as e:
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logger.warning(
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"Charm performing maintenance in section '%s' due to '%s'",
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section,
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str(e),
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)
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charm.status.set(e.to_status())
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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(
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"Exception raised in section '%s': %s", section, str(e)
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)
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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.status.set(
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BlockedStatus(
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"Error in charm (see logs): {}".format(str(e))
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)
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)
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return
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raise
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