# Copyright 2019-2021 Canonical Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Base objects for the Charm, events and metadata."""
import enum
import os
import pathlib
from typing import (
TYPE_CHECKING,
Any,
Dict,
List,
Mapping,
Optional,
TextIO,
Union,
cast,
)
from ops import model
from ops._private import yaml
from ops.framework import EventBase, EventSource, Framework, Object, ObjectEvents
if TYPE_CHECKING:
from typing_extensions import Literal, Required, TypedDict
from ops.framework import Handle, JsonObject, _SerializedData
from ops.model import Container, Numerical, Relation, Storage
# CharmMeta also needs these.
_ActionParam = Dict[str, 'JsonObject'] # <JSON Schema definition>
_ActionMetaDict = TypedDict(
'_ActionMetaDict', {
'title': str,
'description': str,
'params': Dict[str, _ActionParam],
'required': List[str]},
total=False)
_Scopes = Literal['global', 'container']
_RelationMetaDict = TypedDict(
'_RelationMetaDict', {
'interface': Required[str],
'limit': int,
'scope': _Scopes},
total=False)
_MultipleRange = TypedDict('_MultipleRange', {'range': str})
_StorageMetaDict = TypedDict('_StorageMetaDict', {
'type': Required[str],
'description': int,
'shared': bool,
'read-only': bool,
'minimum-size': str,
'location': str,
'multiple-range': str,
'multiple': _MultipleRange
})
_ResourceMetaDict = TypedDict(
'_ResourceMetaDict', {
'type': Required[str],
'filename': str,
'description': str},
total=False)
_PayloadMetaDict = TypedDict('_PayloadMetaDict', {'type': str})
_MountDict = TypedDict(
'_MountDict', {'storage': Required[str],
'location': str},
total=False)
_ContainerMetaDict = TypedDict(
'_ContainerMetaDict', {'mounts': List[_MountDict]})
_CharmMetaDict = TypedDict(
'_CharmMetaDict', { # all are optional
'name': Required[str],
'summary': Required[str],
'description': Required[str],
'maintainer': str,
'maintainers': List[str],
'tags': List[str],
'terms': List[str],
'series': List[str],
'subordinate': bool,
'min-juju-version': str,
'requires': Dict[str, '_RelationMetaDict'],
'provides': Dict[str, '_RelationMetaDict'],
'peers': Dict[str, '_RelationMetaDict'],
'storage': Dict[str, '_StorageMetaDict'],
'resources': Dict[str, '_ResourceMetaDict'],
'payloads': Dict[str, '_PayloadMetaDict'],
'extra-bindings': Dict[str, Any], # fixme: _BindingDict?
'containers': Dict[str, '_ContainerMetaDict']
}, total=False)
# can't put in *Event because *Event.snapshot needs it.
_WorkloadEventSnapshot = TypedDict('_WorkloadEventSnapshot', {
'container_name': str
}, total=False)
_RelationDepartedEventSnapshot = TypedDict('_RelationDepartedEventSnapshot', {
'relation_name': str,
'relation_id': int,
'app_name': Optional[str],
'unit_name': Optional[str],
'departing_unit': Optional[str]
}, total=False)
_StorageEventSnapshot = TypedDict('_StorageEventSnapshot', {
'storage_name': str,
'storage_index': int,
'storage_location': str,
}, total=False)
[docs]class HookEvent(EventBase):
"""Events raised by Juju to progress a charm's lifecycle.
Hooks are callback methods of a charm class (a subclass of
:class:`CharmBase`) that are invoked in response to events raised
by Juju. These callback methods are the means by which a charm
governs the lifecycle of its application.
The :class:`HookEvent` class is the base of a type hierarchy of events
related to the charm's lifecycle.
:class:`HookEvent` subtypes are grouped into the following categories
- Core lifecycle events
- Relation events
- Storage events
- Metric events
"""
[docs]class ActionEvent(EventBase):
"""Events raised by Juju when an administrator invokes a Juju Action.
This class is the data type of events triggered when an administrator
invokes a Juju Action. Callbacks bound to these events may be used
for responding to the administrator's Juju Action request.
To read the parameters for the action, see the instance variable :attr:`params`.
To respond with the result of the action, call :meth:`set_results`. To add
progress messages that are visible as the action is progressing use
:meth:`log`.
Attributes:
params: The parameters passed to the action.
"""
[docs] def defer(self):
"""Action events are not deferable like other events.
This is because an action runs synchronously and the administrator
is waiting for the result.
"""
raise RuntimeError('cannot defer action events')
[docs] def restore(self, snapshot: 'JsonObject'):
"""Used by the operator framework to record the action.
Not meant to be called directly by charm code.
"""
env_action_name = os.environ.get('JUJU_ACTION_NAME')
event_action_name = self.handle.kind[:-len('_action')].replace('_', '-')
if event_action_name != env_action_name:
# This could only happen if the dev manually emits the action, or from a bug.
raise RuntimeError('action event kind does not match current action')
# Params are loaded at restore rather than __init__ because
# the model is not available in __init__.
self.params = self.framework.model._backend.action_get() # pyright: reportPrivateUsage=false # noqa
[docs] def set_results(self, results: '_SerializedData'):
"""Report the result of the action.
Args:
results: The result of the action as a Dict
"""
self.framework.model._backend.action_set(results) # pyright: reportPrivateUsage=false
[docs] def log(self, message: str):
"""Send a message that a user will see while the action is running.
Args:
message: The message for the user.
"""
self.framework.model._backend.action_log(message) # pyright: reportPrivateUsage=false
[docs] def fail(self, message: str = ''):
"""Report that this action has failed.
Args:
message: Optional message to record why it has failed.
"""
self.framework.model._backend.action_fail(message) # pyright: reportPrivateUsage=false
[docs]class InstallEvent(HookEvent):
"""Event triggered when a charm is installed.
This event is triggered at the beginning of a charm's
lifecycle. Any associated callback method should be used to
perform one-time setup operations, such as installing prerequisite
software.
"""
[docs]class StartEvent(HookEvent):
"""Event triggered immediately after first configuration change.
This event is triggered immediately after the first
:class:`ConfigChangedEvent`. Callback methods bound to the event should be
used to ensure that the charm’s software is in a running state. Note that
the charm’s software should be configured so as to persist in this state
through reboots without further intervention on Juju’s part.
"""
[docs]class StopEvent(HookEvent):
"""Event triggered when a charm is shut down.
This event is triggered when an application's removal is requested
by the client. The event fires immediately before the end of the
unit’s destruction sequence. Callback methods bound to this event
should be used to ensure that the charm’s software is not running,
and that it will not start again on reboot.
"""
[docs]class RemoveEvent(HookEvent):
"""Event triggered when a unit is about to be terminated.
This event fires prior to Juju removing the charm and terminating its unit.
"""
[docs]class ConfigChangedEvent(HookEvent):
"""Event triggered when a configuration change occurs.
This event can fire in several situations:
- Right after the unit starts up for the first time.
This event notifies the charm of its initial configuration.
Typically, this event will fire between a :class:`install <InstallEvent>`
and a :class:`starts <StartEvent>` during the startup sequence
(when you first deploy a unit), but more in general it will fire whenever
the unit is (re)started, e.g. after pod churn on kubernetes, on unit
rescheduling, on unit upgrade/refresh, etc...
- As a specific instance of the above point: when networking changes
(if the machine reboots and comes up with a different IP).
- When the cloud admin reconfigures the charm via the juju CLI, i.e.
`juju config my-charm foo=bar`. This event notifies the charm of
its new configuration. (The event itself, however, is now aware of *what*
specifically has changed in the config).
Any callback method bound to this event cannot assume that the
software has already been started; it should not start stopped
software, but should (if appropriate) restart running software to
take configuration changes into account.
"""
[docs]class UpdateStatusEvent(HookEvent):
"""Event triggered by a status update request from Juju.
This event is periodically triggered by Juju so that it can
provide constant feedback to the administrator about the status of
the application the charm is modeling. Any callback method bound
to this event should determine the "health" of the application and
set the status appropriately.
The interval between :class:`update-status <UpdateStatusEvent>` events can
be configured model-wide, e.g. ``juju model-config
update-status-hook-interval=1m``.
"""
[docs]class UpgradeCharmEvent(HookEvent):
"""Event triggered by request to upgrade the charm.
This event will be triggered when an administrator executes ``juju
upgrade-charm``. The event fires after Juju has unpacked the upgraded charm
code, and so this event will be handled by the callback method bound to the
event in the new codebase. The associated callback method is invoked
provided there is no existing error state. The callback method should be
used to reconcile current state written by an older version of the charm
into whatever form that is needed by the current charm version.
"""
[docs]class PreSeriesUpgradeEvent(HookEvent):
"""Event triggered to prepare a unit for series upgrade.
This event triggers when an administrator executes ``juju upgrade-series
MACHINE prepare``. The event will fire for each unit that is running on the
specified machine. Any callback method bound to this event must prepare the
charm for an upgrade to the series. This may include things like exporting
database content to a version neutral format, or evacuating running
instances to other machines.
It can be assumed that only after all units on a machine have executed the
callback method associated with this event, the administrator will initiate
steps to actually upgrade the series. After the upgrade has been completed,
the :class:`PostSeriesUpgradeEvent` will fire.
"""
[docs]class PostSeriesUpgradeEvent(HookEvent):
"""Event triggered after a series upgrade.
This event is triggered after the administrator has done a distribution
upgrade (or rolled back and kept the same series). It is called in response
to ``juju upgrade-series MACHINE complete``. Associated charm callback
methods are expected to do whatever steps are necessary to reconfigure their
applications for the new series. This may include things like populating the
upgraded version of a database. Note however charms are expected to check if
the series has actually changed or whether it was rolled back to the
original series.
"""
[docs]class LeaderElectedEvent(HookEvent):
"""Event triggered when a new leader has been elected.
Juju will trigger this event when a new leader unit is chosen for
a given application.
This event fires at least once after Juju selects a leader
unit. Callback methods bound to this event may take any action
required for the elected unit to assert leadership. Note that only
the elected leader unit will receive this event.
"""
[docs]class LeaderSettingsChangedEvent(HookEvent):
"""Event triggered when leader changes any settings.
DEPRECATED NOTICE
This event has been deprecated in favor of using a Peer relation,
and having the leader set a value in the Application data bag for
that peer relation. (see :class:`RelationChangedEvent`).
"""
[docs]class CollectMetricsEvent(HookEvent):
"""Event triggered by Juju to collect metrics.
Juju fires this event every five minutes for the lifetime of the
unit. Callback methods bound to this event may use the :meth:`add_metrics`
method of this class to send measurements to Juju.
Note that associated callback methods are currently sandboxed in
how they can interact with Juju.
"""
[docs] def add_metrics(self, metrics: Mapping[str, 'Numerical'],
labels: Optional[Mapping[str, str]] = None):
"""Record metrics that have been gathered by the charm for this unit.
Args:
metrics: A collection of {key: float} pairs that contains the
metrics that have been gathered
labels: {key:value} strings that can be applied to the
metrics that are being gathered
"""
self.framework.model._backend.add_metrics(metrics, labels) # type:ignore
[docs]class RelationEvent(HookEvent):
"""A base class representing the various relation lifecycle events.
Relation lifecycle events are generated when application units
participate in relations. Units can only participate in relations
after they have been "started", and before they have been
"stopped". Within that time window, the unit may participate in
several different relations at a time, including multiple
relations with the same name.
Attributes:
relation: The :class:`~ops.model.Relation` involved in this event
app: The remote :class:`~ops.model.Application` that has triggered this
event
unit: The remote :class:`~ops.model.Unit` that has triggered this event. This may be
``None`` if the relation event was triggered as an
:class:`~ops.model.Application` level event
"""
if TYPE_CHECKING:
_RelationEventSnapshot = TypedDict('_RelationEventSnapshot', {
'relation_name': Required[str],
'relation_id': Required[int],
'app_name': Optional[str],
'unit_name': Optional[str]
}, total=False)
def __init__(self, handle: 'Handle', relation: 'Relation',
app: Optional[model.Application] = None,
unit: Optional[model.Unit] = None):
super().__init__(handle)
if unit is not None and unit.app != app:
raise RuntimeError(
'cannot create RelationEvent with application {} and unit {}'.format(app, unit))
self.relation = relation
self.app = app
self.unit = unit
[docs] def snapshot(self) -> '_RelationEventSnapshot':
"""Used by the framework to serialize the event to disk.
Not meant to be called by charm code.
"""
snapshot = {
'relation_name': self.relation.name,
'relation_id': self.relation.id,
} # type: 'RelationEvent._RelationEventSnapshot'
if self.app:
snapshot['app_name'] = self.app.name
if self.unit:
snapshot['unit_name'] = self.unit.name
return snapshot
[docs] def restore(self, snapshot: '_RelationEventSnapshot'):
"""Used by the framework to deserialize the event from disk.
Not meant to be called by charm code.
"""
relation = self.framework.model.get_relation(
snapshot['relation_name'], snapshot['relation_id'])
if relation is None:
raise ValueError(
'Unable to restore {}: relation {} (id={}) not found.'.format(
self, snapshot['relation_name'], snapshot['relation_id']))
self.relation = relation
app_name = snapshot.get('app_name')
if app_name:
self.app = self.framework.model.get_app(app_name)
else:
self.app = None
unit_name = snapshot.get('unit_name')
if unit_name:
self.unit = self.framework.model.get_unit(unit_name)
else:
self.unit = None
[docs]class RelationCreatedEvent(RelationEvent):
"""Event triggered when a new relation is created.
This is triggered when a new relation to another app is added in Juju. This
can occur before units for those applications have started. All existing
relations should be established before start.
"""
[docs]class RelationJoinedEvent(RelationEvent):
"""Event triggered when a new unit joins a relation.
This event is triggered whenever a new unit of a related
application joins the relation. The event fires only when that
remote unit is first observed by the unit. Callback methods bound
to this event may set any local unit settings that can be
determined using no more than the name of the joining unit and the
remote ``private-address`` setting, which is always available when
the relation is created and is by convention not deleted.
"""
[docs]class RelationChangedEvent(RelationEvent):
"""Event triggered when relation data changes.
This event is triggered whenever there is a change to the data bucket for a
related application or unit. Look at ``event.relation.data[event.unit/app]``
to see the new information, where ``event`` is the event object passed to
the callback method bound to this event.
This event always fires once, after :class:`RelationJoinedEvent`, and
will subsequently fire whenever that remote unit changes its settings for
the relation. Callback methods bound to this event should be the only ones
that rely on remote relation settings. They should not error if the settings
are incomplete, since it can be guaranteed that when the remote unit or
application changes its settings, the event will fire again.
The settings that may be queried, or set, are determined by the relation’s
interface.
"""
[docs]class RelationDepartedEvent(RelationEvent):
"""Event triggered when a unit leaves a relation.
This is the inverse of the :class:`RelationJoinedEvent`, representing when a
unit is leaving the relation (the unit is being removed, the app is being
removed, the relation is being removed). For remaining units, this event is
emitted once for each departing unit. For departing units, this event is
emitted once for each remaining unit.
Callback methods bound to this event may be used to remove all
references to the departing remote unit, because there’s no
guarantee that it’s still part of the system; it’s perfectly
probable (although not guaranteed) that the system running that
unit has already shut down.
Once all callback methods bound to this event have been run for such a
relation, the unit agent will fire the :class:`RelationBrokenEvent`.
Attributes:
departing_unit: The :class:`~ops.model.Unit` that is departing. This
can facilitate determining e.g. whether *you* are the departing
unit.
"""
def __init__(self, handle: 'Handle', relation: 'Relation',
app: Optional[model.Application] = None,
unit: Optional[model.Unit] = None,
departing_unit_name: Optional[str] = None):
super().__init__(handle, relation, app=app, unit=unit)
self._departing_unit_name = departing_unit_name
[docs] def snapshot(self) -> '_RelationDepartedEventSnapshot':
"""Used by the framework to serialize the event to disk.
Not meant to be called by charm code.
"""
snapshot = cast('_RelationDepartedEventSnapshot', super().snapshot())
if self._departing_unit_name:
snapshot['departing_unit'] = self._departing_unit_name
return snapshot
@property
def departing_unit(self) -> Optional[model.Unit]:
"""The `ops.model.Unit` that is departing, if any."""
# doing this on init would fail because `framework` gets patched in
# post-init
if not self._departing_unit_name:
return None
return self.framework.model.get_unit(self._departing_unit_name)
[docs] def restore(self, snapshot: '_RelationDepartedEventSnapshot'):
"""Used by the framework to deserialize the event from disk.
Not meant to be called by charm code.
"""
super().restore(snapshot) # type: ignore
self._departing_unit_name = snapshot.get('departing_unit')
[docs]class RelationBrokenEvent(RelationEvent):
"""Event triggered when a relation is removed.
If a relation is being removed (``juju remove-relation`` or ``juju
remove-application``), once all the units have been removed, this event will
fire to signal that the relationship has been fully terminated.
The event indicates that the current relation is no longer valid, and that
the charm’s software must be configured as though the relation had never
existed. It will only be called after every callback method bound to
:class:`RelationDepartedEvent` has been run. If a callback method
bound to this event is being executed, it is guaranteed that no remote units
are currently known locally.
"""
[docs]class StorageEvent(HookEvent):
"""Base class representing storage-related events.
Juju can provide a variety of storage types to a charms. The
charms can define several different types of storage that are
allocated from Juju. Changes in state of storage trigger sub-types
of :class:`StorageEvent`.
"""
def __init__(self, handle: 'Handle', storage: 'Storage'):
super().__init__(handle)
self.storage = storage
[docs] def snapshot(self) -> '_StorageEventSnapshot':
"""Used by the framework to serialize the event to disk.
Not meant to be called by charm code.
"""
snapshot = {} # type: '_StorageEventSnapshot'
if isinstance(self.storage, model.Storage):
snapshot["storage_name"] = self.storage.name
snapshot["storage_index"] = self.storage.index
snapshot["storage_location"] = str(self.storage.location)
return snapshot
[docs] def restore(self, snapshot: '_StorageEventSnapshot'):
"""Used by the framework to deserialize the event from disk.
Not meant to be called by charm code.
"""
storage_name = snapshot.get("storage_name")
storage_index = snapshot.get("storage_index")
storage_location = snapshot.get("storage_location")
if storage_name and storage_index is not None:
storages = self.framework.model.storages[storage_name]
self.storage = next((s for s in storages if s.index == storage_index), None,)
if self.storage is None:
msg = 'failed loading storage (name={!r}, index={!r}) from snapshot' \
.format(storage_name, storage_index)
raise RuntimeError(msg)
if storage_location is None:
raise RuntimeError(
'failed loading storage location from snapshot.'
'(name={!r}, index={!r}, storage_location=None)'
.format(storage_name, storage_index))
self.storage.location = storage_location
[docs]class StorageAttachedEvent(StorageEvent):
"""Event triggered when new storage becomes available.
This event is triggered when new storage is available for the
charm to use.
Callback methods bound to this event allow the charm to run code
when storage has been added. Such methods will be run before the
:class:`InstallEvent` fires, so that the installation routine may
use the storage. The name prefix of this hook will depend on the
storage key defined in the ``metadata.yaml`` file.
"""
[docs]class StorageDetachingEvent(StorageEvent):
"""Event triggered prior to removal of storage.
This event is triggered when storage a charm has been using is
going away.
Callback methods bound to this event allow the charm to run code
before storage is removed. Such methods will be run before storage
is detached, and always before the :class:`StopEvent` fires, thereby
allowing the charm to gracefully release resources before they are
removed and before the unit terminates. The name prefix of the
hook will depend on the storage key defined in the ``metadata.yaml``
file.
"""
[docs]class WorkloadEvent(HookEvent):
"""Base class representing workload-related events.
Workload events are generated for all containers that the charm
expects in metadata. Workload containers currently only trigger
a PebbleReadyEvent.
Attributes:
workload: The :class:`~ops.model.Container` involved in this event.
Workload currently only can be a Container but in future may
be other types that represent the specific workload type e.g.
a Machine.
"""
def __init__(self, handle: 'Handle', workload: 'Container'):
super().__init__(handle)
self.workload = workload
[docs] def snapshot(self) -> '_WorkloadEventSnapshot':
"""Used by the framework to serialize the event to disk.
Not meant to be called by charm code.
"""
snapshot = {} # type: "_WorkloadEventSnapshot"
if isinstance(self.workload, model.Container):
snapshot['container_name'] = self.workload.name
return snapshot
[docs] def restore(self, snapshot: '_WorkloadEventSnapshot'):
"""Used by the framework to deserialize the event from disk.
Not meant to be called by charm code.
"""
container_name = snapshot.get('container_name')
if container_name:
self.workload = self.framework.model.unit.get_container(container_name)
else:
self.workload = None
[docs]class PebbleReadyEvent(WorkloadEvent):
"""Event triggered when pebble is ready for a workload.
This event is triggered when the Pebble process for a workload/container
starts up, allowing the charm to configure how services should be launched.
Callback methods bound to this event allow the charm to run code after
a workload has started its Pebble instance and is ready to receive instructions
regarding what services should be started. The name prefix of the hook
will depend on the container key defined in the ``metadata.yaml`` file.
"""
[docs]class CharmEvents(ObjectEvents):
"""Events generated by Juju pertaining to application lifecycle.
This class is used to create an event descriptor (``self.on``) attribute for
a charm class that inherits from :class:`CharmBase`. The event descriptor
may be used to set up event handlers for corresponding events.
By default the following events will be provided through
:class:`CharmBase`::
self.on.install
self.on.start
self.on.remove
self.on.update_status
self.on.config_changed
self.on.upgrade_charm
self.on.pre_series_upgrade
self.on.post_series_upgrade
self.on.leader_elected
self.on.collect_metrics
In addition to these, depending on the charm's metadata (``metadata.yaml``),
named relation and storage events may also be defined. These named events
are created by :class:`CharmBase` using charm metadata. The named events may be
accessed as ``self.on[<name>].<relation_or_storage_event>``
"""
install = EventSource(InstallEvent)
start = EventSource(StartEvent)
stop = EventSource(StopEvent)
remove = EventSource(RemoveEvent)
update_status = EventSource(UpdateStatusEvent)
config_changed = EventSource(ConfigChangedEvent)
upgrade_charm = EventSource(UpgradeCharmEvent)
pre_series_upgrade = EventSource(PreSeriesUpgradeEvent)
post_series_upgrade = EventSource(PostSeriesUpgradeEvent)
leader_elected = EventSource(LeaderElectedEvent)
leader_settings_changed = EventSource(LeaderSettingsChangedEvent)
collect_metrics = EventSource(CollectMetricsEvent)
[docs]class CharmBase(Object):
"""Base class that represents the charm overall.
:class:`CharmBase` is used to create a charm. This is done by inheriting
from :class:`CharmBase` and customising the sub class as required. So to
create your own charm, say ``MyCharm``, define a charm class and set up the
required event handlers (“hooks”) in its constructor::
import logging
from ops.charm import CharmBase
from ops.main import main
logger = logging.getLogger(__name__)
def MyCharm(CharmBase):
def __init__(self, *args):
logger.debug('Initializing Charm')
super().__init__(*args)
self.framework.observe(self.on.config_changed, self._on_config_changed)
self.framework.observe(self.on.stop, self._on_stop)
# ...
if __name__ == "__main__":
main(MyCharm)
As shown in the example above, a charm class is instantiated by
:func:`~ops.main.main` rather than charm authors directly instantiating a
charm.
Args:
framework: The framework responsible for managing the Model and events for this
charm.
key: Ignored; will remove after deprecation period of the signature change.
"""
# note that without the #: below, sphinx will copy the whole of CharmEvents
# docstring inline which is less than ideal.
# Used to set up event handlers; see :class:`CharmEvents`.
on = CharmEvents() # type: ignore
if TYPE_CHECKING:
# to help the type checker and IDEs:
[docs] @property
def on(self) -> CharmEvents: ... # noqa
def __init__(self, framework: Framework, key: Optional[str] = None):
super().__init__(framework, None)
for relation_name in self.framework.meta.relations:
relation_name = relation_name.replace('-', '_')
self.on.define_event(relation_name + '_relation_created', RelationCreatedEvent)
self.on.define_event(relation_name + '_relation_joined', RelationJoinedEvent)
self.on.define_event(relation_name + '_relation_changed', RelationChangedEvent)
self.on.define_event(relation_name + '_relation_departed', RelationDepartedEvent)
self.on.define_event(relation_name + '_relation_broken', RelationBrokenEvent)
for storage_name in self.framework.meta.storages:
storage_name = storage_name.replace('-', '_')
self.on.define_event(storage_name + '_storage_attached', StorageAttachedEvent)
self.on.define_event(storage_name + '_storage_detaching', StorageDetachingEvent)
for action_name in self.framework.meta.actions:
action_name = action_name.replace('-', '_')
self.on.define_event(action_name + '_action', ActionEvent)
for container_name in self.framework.meta.containers:
container_name = container_name.replace('-', '_')
self.on.define_event(container_name + '_pebble_ready', PebbleReadyEvent)
@property
def app(self) -> model.Application:
"""Application that this unit is part of."""
return self.framework.model.app
@property
def unit(self) -> model.Unit:
"""Unit that this execution is responsible for."""
return self.framework.model.unit
@property
def meta(self) -> 'CharmMeta':
"""Metadata of this charm."""
return self.framework.meta
@property
def charm_dir(self) -> pathlib.Path:
"""Root directory of the charm as it is running."""
return self.framework.charm_dir
@property
def config(self) -> model.ConfigData:
"""A mapping containing the charm's config and current values."""
return self.model.config
[docs]class RelationRole(enum.Enum):
"""An annotation for a charm's role in a relation.
For each relation a charm's role may be
- A Peer
- A service consumer in the relation ('requires')
- A service provider in the relation ('provides')
"""
peer = 'peer'
requires = 'requires'
provides = 'provides'
[docs] def is_peer(self) -> bool:
"""Return whether the current role is peer.
A convenience to avoid having to import charm.
"""
return self is RelationRole.peer