feat(refresh): port the VM post-refresh flows (4/6)

refresh_versions.toml

@@ -0,0 +1,2 @@
+charm = "16/0.0.0"
+workload = "16.0"

single_kernel_postgresql/charms/abstract_charm.py

@@ -100,6 +100,9 @@ def __init__(self, *args):
             self.patroni_manager,
         )
 
+        # Resume or prepare the refresh (the charms' post-construction resume block).
+        self.refresh_manager.on_init()
+
         # Status Handler
         self.status_handler = StatusHandler(
             self,
@@ -177,10 +180,37 @@ def set_app_status(self) -> None:
         pass
 
     @abstractmethod
-    def update_config(self) -> bool:
+    def update_config(self, *, refresh: "charm_refresh.Machines | None" = None) -> bool:
         """Re-render the Patroni configuration and apply it."""
         pass
 
+    @abstractmethod
+    def post_refresh_side_effects(self) -> None:
+        """Run the post-snap-refresh side effects owned by not-yet-migrated modules.
+
+        The VM charm sets up the exporter and pgBackRest exporter, starts/stops the
+        pgBackRest service and updates the watcher unit address here.
+        """
+        pass
+
+    @abstractmethod
+    def has_async_replication_relation(self) -> bool:
+        """Whether this unit is related to an async replication partner.
+
+        Owned by the async-replication module until that phase migrates; the temp
+        tablespace migration skips units inside an async cluster.
+        """
+        pass
+
+    @abstractmethod
+    def update_relation_endpoints(self) -> None:
+        """Refresh the client and async relation endpoints after a switchover.
+
+        Owned by the client-relation and async-replication modules until those
+        phases migrate; the VM pre-refresh checks call it after switching primary.
+        """
+        pass
+
     @property
     @abstractmethod
     def primary_endpoint(self) -> str | None:

single_kernel_postgresql/charms/k8s_charm.py

@@ -89,7 +89,7 @@ def set_unit_status(
         status: StatusBase,
         /,
         *,
-        refresh: "charm_refresh.Kubernetes | None" = None,
+        refresh: "charm_refresh.Machines | charm_refresh.Kubernetes | None" = None,
     ) -> None:
         """Set the unit status without overriding a higher-priority refresh status."""
         self.refresh_manager.set_unit_status(status, refresh=refresh)
@@ -101,7 +101,16 @@ def set_default_unit_status(self) -> None:
     def set_app_status(self) -> None:
         """Set the application status from the async-replication state."""
 
-    def update_config(self, *, refresh: "charm_refresh.Kubernetes | None" = None) -> bool:
+    def post_refresh_side_effects(self) -> None:
+        """Run the post-snap-refresh side effects owned by not-yet-migrated modules."""
+
+    def has_async_replication_relation(self) -> bool:
+        """Whether this unit is related to an async replication partner."""
+        return False
+
+    def update_config(
+        self, *, refresh: "charm_refresh.Machines | charm_refresh.Kubernetes | None" = None
+    ) -> bool:
         """Re-render the Patroni configuration and apply it."""
         return self.config_manager.update_config(self.postgresql)
 
@@ -113,3 +122,6 @@ def primary_endpoint(self) -> str | None:
     def get_async_primary_cluster_endpoint(self) -> str | None:
         """Endpoint of the primary cluster of the async replication partner, if any."""
         return None
+
+    def update_relation_endpoints(self) -> None:
+        """Refresh the client and async relation endpoints after a switchover."""

single_kernel_postgresql/charms/vm_charm.py

@@ -80,7 +80,7 @@ def set_unit_status(
         status: StatusBase,
         /,
         *,
-        refresh: "charm_refresh.Machines | None" = None,
+        refresh: "charm_refresh.Machines | charm_refresh.Kubernetes | None" = None,
     ) -> None:
         """Set the unit status without overriding a higher-priority refresh status."""
         self.refresh_manager.set_unit_status(status, refresh=refresh)
@@ -92,7 +92,16 @@ def set_default_unit_status(self) -> None:
     def set_app_status(self) -> None:
         """Set the application status from the async-replication state."""
 
-    def update_config(self, *, refresh: "charm_refresh.Machines | None" = None) -> bool:
+    def post_refresh_side_effects(self) -> None:
+        """Set up the exporters, pgBackRest service, and watcher unit address."""
+
+    def has_async_replication_relation(self) -> bool:
+        """Whether this unit is related to an async replication partner."""
+        return False
+
+    def update_config(
+        self, *, refresh: "charm_refresh.Machines | charm_refresh.Kubernetes | None" = None
+    ) -> bool:
         """Re-render the Patroni configuration and apply it."""
         if refresh is None:
             refresh = self.refresh_manager.refresh
@@ -107,3 +116,6 @@ def primary_endpoint(self) -> str | None:
     def get_async_primary_cluster_endpoint(self) -> str | None:
         """Endpoint of the primary cluster of the async replication partner, if any."""
         return None
+
+    def update_relation_endpoints(self) -> None:
+        """Refresh the client and async relation endpoints after a switchover."""

single_kernel_postgresql/managers/config.py

@@ -479,7 +479,7 @@ def update_config(
         watcher_raft_address: str | None = None,
         no_peers: bool = False,
         *,
-        refresh: charm_refresh.Machines | None = None,
+        refresh: charm_refresh.Machines | charm_refresh.Kubernetes | None = None,
     ) -> bool:
         """Updates Patroni config file based on the existence of the TLS files.
 
@@ -578,7 +578,7 @@ def update_config(
             self.state.substrate == Substrates.VM
             and refresh is not None
             and cast("VMWorkload", self.workload).get_snap_revision()
-            != refresh.pinned_snap_revision
+            != cast("charm_refresh.Machines", refresh).pinned_snap_revision
         ):
             logger.debug("Early exit: snap was not refreshed to the right version yet")
             return True