observe on.start event to make start up process more robust (#292)

* observe on.start event to avoid intermediate erros status

* fix scenario tests

src/charm.py

@@ -165,6 +165,7 @@ def __init__(self, *args):
 
  # Core lifecycle events
  self.framework.observe(self.on.config_changed, self._on_config_changed)
+ self.framework.observe(self.on.start, self._on_start)
 
  peer_ha_netlocs = [
  f"{hostname}:{self._ports.ha}"
@@ -487,6 +488,10 @@ def _on_config_changed(self, _):
  """Event handler for ConfigChangedEvent."""
  self._common_exit_hook(update_ca_certs=True)
 
+ def _on_start(self, _):
+ """Event handler for ConfigChangedEvent."""
+ self._common_exit_hook(update_ca_certs=True)
+
  def _on_peer_relation_joined(self, _):
  """Event handler for replica's RelationChangedEvent."""
  self._common_exit_hook()

tests/scenario/conftest.py

@@ -23,6 +23,8 @@ def alertmanager_charm():
  is_ready=tautology,
  ), patch.object(WorkloadManager, "check_config", lambda *a, **kw: ("ok", "")), patch.object(
  WorkloadManager, "_alertmanager_version", property(lambda *_: "0.0.0")
+ ), patch(
+ "subprocess.run"
  ):
  yield AlertmanagerCharm
 

tests/scenario/helpers.py

@@ -1,11 +1,20 @@
 # Copyright 2023 Canonical Ltd.
 # See LICENSE file for licensing details.
 
-from scenario import Container, Context, PeerRelation, Relation, State
+from scenario import Container, Context, ExecOutput, PeerRelation, Relation, State
 
 
 def begin_with_initial_hooks_isolated(context: Context, *, leader: bool = True) -> State:
- container = Container("alertmanager", can_connect=False)
+ container = Container(
+ "alertmanager",
+ can_connect=False,
+ exec_mock={
+ ("update-ca-certificates", "--fresh"): ExecOutput( # this is the command we're mocking
+ return_code=0, # this data structure contains all we need to mock the call.
+ stdout="OK",
+ )
+ },
+ )
  state = State(config={"config_file": ""}, containers=[container])
  peer_rel = PeerRelation("replicas")
 

tox.ini

@@ -100,7 +100,7 @@ commands =
 description = Scenario tests
 deps =
  pytest
- ops-scenario>=6
+ ops-scenario<7
  cosl
  -r{toxinidir}/requirements.txt
 commands =