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canonical / prometheus-k8s-operator

https://charmhub.io/prometheus-k8s
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break relation causes error state #387

Closed beliaev-maksim closed 1 year ago

beliaev-maksim commented 2 years ago

Bug Description

either I am doing something wrong, but every time I remove relation, I get an error state with below mentioned trace.

path of the code that raises an error is: https://github.com/canonical/prometheus-k8s-operator/blob/dc3dc60f198f8dfc840f4da6f98f295ff8b9b97d/lib/charms/prometheus_k8s/v0/prometheus_remote_write.py#L643

and in this case it looks like either event does not have app attribute or it is None. Which produces event.relation.data[None] and that causes an error.

simple fix will be to check for event.app, but I am not sure I do everything correct

To Reproduce

relate two charms like juju relate prometheus-k8s:send-remote-write prom-read:receive-remote-write

break relation: juju remove-relation prometheus-k8s prom-read

Environment

microk8s

Relevant log output

ERROR unit.prometheus-k8s/0.juju-log send-remote-write:22: Uncaught exception while in charm code:
Traceback (most recent call last):
  File "./src/charm.py", line 806, in <module>
    main(PrometheusCharm)
  File "/var/lib/juju/agents/unit-prometheus-k8s-0/charm/venv/ops/main.py", line 431, in main
    _emit_charm_event(charm, dispatcher.event_name)
  File "/var/lib/juju/agents/unit-prometheus-k8s-0/charm/venv/ops/main.py", line 142, in _emit_charm_event
    event_to_emit.emit(*args, **kwargs)
  File "/var/lib/juju/agents/unit-prometheus-k8s-0/charm/venv/ops/framework.py", line 316, in emit
    framework._emit(event)
  File "/var/lib/juju/agents/unit-prometheus-k8s-0/charm/venv/ops/framework.py", line 784, in _emit
    self._reemit(event_path)
  File "/var/lib/juju/agents/unit-prometheus-k8s-0/charm/venv/ops/framework.py", line 857, in _reemit
    custom_handler(event)
  File "/var/lib/juju/agents/unit-prometheus-k8s-0/charm/lib/charms/prometheus_k8s/v0/prometheus_remote_write.py", line 644, in _handle_endpoints_changed
    ev = json.loads(event.relation.data[event.app].get("event", "{}"))
  File "/var/lib/juju/agents/unit-prometheus-k8s-0/charm/venv/ops/model.py", line 899, in __getitem__
    return self._data[key]
KeyError: None

Additional context

No response