[MISC] Don't set tls flag if relation isn't initialised

[dragomirp]

Issue

Reported on Matrix: https://matrix.to/#/!BukWfnyOTgQSKAxdtT:ubuntu.com/$h83Y4pRMpwZ06KMS0IDc4Y7KZmg85ZAfn6IcGsra3N4?via=ubuntu.com&via=matrix.org&via=laquadrature.net

Setting the TLS flag and CA can violate the data interfaces handshake, by setting them before the client relation is ready:

unit-postgresql-k8s-0: 08:51:37 ERROR unit.postgresql-k8s/0.juju-log database-peers:2: Uncaught exception while in charm code:
Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/src/charm.py", line 2252, in <module>
    main(PostgresqlOperatorCharm, use_juju_for_storage=True)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/venv/lib/python3.10/site-packages/ops/__init__.py", line 343, in __call__
    return _main.main(charm_class=charm_class, use_juju_for_storage=use_juju_for_storage)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/venv/lib/python3.10/site-packages/ops/_main.py", line 543, in main
    manager.run()
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/venv/lib/python3.10/site-packages/ops/_main.py", line 529, in run
    self._emit()
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/venv/lib/python3.10/site-packages/ops/_main.py", line 518, in _emit
    _emit_charm_event(self.charm, self.dispatcher.event_name, self._juju_context)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/venv/lib/python3.10/site-packages/ops/_main.py", line 134, in _emit_charm_event
    event_to_emit.emit(*args, **kwargs)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/venv/lib/python3.10/site-packages/ops/framework.py", line 347, in emit
    framework._emit(event)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/venv/lib/python3.10/site-packages/ops/framework.py", line 857, in _emit
    self._reemit(event_path)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/venv/lib/python3.10/site-packages/ops/framework.py", line 947, in _reemit
    custom_handler(event)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/lib/charms/tempo_coordinator_k8s/v0/charm_tracing.py", line 1065, in wrapped_function
    return callable(*args, **kwargs)  # type: ignore
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/src/charm.py", line 556, in _on_peer_relation_changed
    self.update_config()
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/lib/charms/tempo_coordinator_k8s/v0/charm_tracing.py", line 1065, in wrapped_function
    return callable(*args, **kwargs)  # type: ignore
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/src/charm.py", line 1905, in update_config
    self._handle_postgresql_restart_need()
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/lib/charms/tempo_coordinator_k8s/v0/charm_tracing.py", line 1065, in wrapped_function
    return callable(*args, **kwargs)  # type: ignore
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/src/charm.py", line 1967, in _handle_postgresql_restart_need
    self.postgresql_client_relation.update_tls_flag("True" if self.is_tls_enabled else "False")
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/lib/charms/tempo_coordinator_k8s/v0/charm_tracing.py", line 1065, in wrapped_function
    return callable(*args, **kwargs)  # type: ignore
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/src/relations/postgresql_provider.py", line 224, in update_tls_flag
    self.database_provides.set_tls(relation.id, tls)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/lib/charms/data_platform_libs/v0/data_interfaces.py", line 1683, in set_tls
    self.update_relation_data(relation_id, {"tls": tls})
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/lib/charms/data_platform_libs/v0/data_interfaces.py", line 496, in wrapper
    return f(self, *args, **kwargs)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/lib/charms/data_platform_libs/v0/data_interfaces.py", line 1407, in update_relation_data
    return self._update_relation_data(relation, data)
  File "/var/lib/juju/agents/unit-postgresql-k8s-0/charm/lib/charms/data_platform_libs/v0/data_interfaces.py", line 1632, in _update_relation_data
    raise PrematureDataAccessError(
charms.data_platform_libs.v0.data_interfaces.PrematureDataAccessError: Premature access to relation data, update is forbidden before the connection is initialized.
unit-postgresql-k8s-0: 08:51:37 ERROR juju.worker.uniter.operation hook "database-peers-relation-changed" (via hook dispatching script: dispatch) failed: exit status 1

VM shouldn't be affected, since it has a separate update endpoints function setting this flag.

Solution

• Check if database is set in the relation data before setting the tls flag and CA
• Disable ignore of errors during early deploy

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.79%. Comparing base (94c25c3) to head (c6adfba).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #933      +/-   ##
==========================================
+ Coverage   74.63%   74.79%   +0.16%     
==========================================
  Files          13       13              
  Lines        3737     3738       +1     
  Branches      550      551       +1     
==========================================
+ Hits         2789     2796       +7     
+ Misses        743      737       -6     
  Partials      205      205              

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[dragomirp]

Check if the relation is already properly intialised. If not the values should be set by the database_requested hook.

[dragomirp]

We ignored this due to early volume mount errors, but it will also hide other errors during start up.

[marceloneppel]

Thanks!