Standardize abstract_charm.py file with the K8s charm (#182)

## Issue
The `abstract_charm.py` has diverged with the K8s charm following in
support of HACluster charm integration + `expose-external` config in the
K8s charm.

## Solution
Standardize the files

Counterpart PR in K8s charm:
canonical/mysql-router-k8s-operator#328

.github/workflows/ci.yaml

@@ -66,7 +66,7 @@ jobs:
 
   build:
     name: Build charm
-    uses: canonical/data-platform-workflows/.github/workflows/[email protected].0
+    uses: canonical/data-platform-workflows/.github/workflows/[email protected].1
     with:
       # Use of cache blocked by https://github.com/canonical/charmcraft/issues/1456
       # Details: https://github.com/canonical/charmcraftcache/issues/3

.github/workflows/release.yaml

@@ -15,14 +15,14 @@ jobs:
 
   build:
     name: Build charm
-    uses: canonical/data-platform-workflows/.github/workflows/[email protected].0
+    uses: canonical/data-platform-workflows/.github/workflows/[email protected].1
 
   release:
     name: Release charm
     needs:
       - ci-tests
       - build
-    uses: canonical/data-platform-workflows/.github/workflows/[email protected].0
+    uses: canonical/data-platform-workflows/.github/workflows/[email protected].1
     with:
       channel: dpe/edge
       artifact-prefix: ${{ needs.build.outputs.artifact-prefix }}

.github/workflows/sync_docs.yaml

@@ -10,7 +10,7 @@ on:
 jobs:
   sync-docs:
     name: Sync docs from Discourse
-    uses: canonical/data-platform-workflows/.github/workflows/[email protected].0
+    uses: canonical/data-platform-workflows/.github/workflows/[email protected].1
     with:
       reviewers: a-velasco
     permissions:

lib/charms/data_platform_libs/v0/data_interfaces.py

@@ -331,7 +331,7 @@ def _on_topic_requested(self, event: TopicRequestedEvent):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 39
+LIBPATCH = 40
 
 PYDEPS = ["ops>=2.0.0"]
 
@@ -391,6 +391,10 @@ class IllegalOperationError(DataInterfacesError):
     """To be used when an operation is not allowed to be performed."""
 
 
+class PrematureDataAccessError(DataInterfacesError):
+    """To be raised when the Relation Data may be accessed (written) before protocol init complete."""
+
+
 ##############################################################################
 # Global helpers / utilities
 ##############################################################################
@@ -1453,6 +1457,8 @@ def _on_relation_changed_event(self, event: RelationChangedEvent) -> None:
 class ProviderData(Data):
     """Base provides-side of the data products relation."""
 
+    RESOURCE_FIELD = "database"
+
     def __init__(
         self,
         model: Model,
@@ -1618,6 +1624,15 @@ def _fetch_my_specific_relation_data(
     def _update_relation_data(self, relation: Relation, data: Dict[str, str]) -> None:
         """Set values for fields not caring whether it's a secret or not."""
         req_secret_fields = []
+
+        keys = set(data.keys())
+        if self.fetch_relation_field(relation.id, self.RESOURCE_FIELD) is None and (
+            keys - {"endpoints", "read-only-endpoints", "replset"}
+        ):
+            raise PrematureDataAccessError(
+                "Premature access to relation data, update is forbidden before the connection is initialized."
+            )
+
         if relation.app:
             req_secret_fields = get_encoded_list(relation, relation.app, REQ_SECRET_FIELDS)
 
@@ -3290,6 +3305,8 @@ class KafkaRequiresEvents(CharmEvents):
 class KafkaProviderData(ProviderData):
     """Provider-side of the Kafka relation."""
 
+    RESOURCE_FIELD = "topic"
+
     def __init__(self, model: Model, relation_name: str) -> None:
         super().__init__(model, relation_name)
 
@@ -3539,6 +3556,8 @@ class OpenSearchRequiresEvents(CharmEvents):
 class OpenSearchProvidesData(ProviderData):
     """Provider-side of the OpenSearch relation."""
 
+    RESOURCE_FIELD = "index"
+
     def __init__(self, model: Model, relation_name: str) -> None:
         super().__init__(model, relation_name)
 

lib/charms/tempo_coordinator_k8s/v0/charm_tracing.py

@@ -69,6 +69,9 @@ def my_tracing_endpoint(self) -> Optional[str]:
     - every event as a span (including custom events)
     - every charm method call (except dunders) as a span
 
+We recommend that you scale up your tracing provider and relate it to an ingress so that your tracing requests
+go through the ingress and get load balanced across all units. Otherwise, if the provider's leader goes down, your tracing goes down.
+
 
 ## TLS support
 If your charm integrates with a TLS provider which is also trusted by the tracing provider (the Tempo charm),
@@ -269,7 +272,7 @@ def _remove_stale_otel_sdk_packages():
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
 
-LIBPATCH = 2
+LIBPATCH = 3
 
 PYDEPS = ["opentelemetry-exporter-otlp-proto-http==1.21.0"]
 

lib/charms/tempo_coordinator_k8s/v0/tracing.py

@@ -34,7 +34,7 @@ def __init__(self, *args):
 `TracingEndpointRequirer.request_protocols(*protocol:str, relation:Optional[Relation])` method.
 Using this method also allows you to use per-relation protocols.
 
-Units of provider charms obtain the tempo endpoint to which they will push their traces by calling
+Units of requirer charms obtain the tempo endpoint to which they will push their traces by calling
 `TracingEndpointRequirer.get_endpoint(protocol: str)`, where `protocol` is, for example:
 - `otlp_grpc`
 - `otlp_http`
@@ -44,7 +44,10 @@ def __init__(self, *args):
 If the `protocol` is not in the list of protocols that the charm requested at endpoint set-up time,
 the library will raise an error.
 
-## Requirer Library Usage
+We recommend that you scale up your tracing provider and relate it to an ingress so that your tracing requests
+go through the ingress and get load balanced across all units. Otherwise, if the provider's leader goes down, your tracing goes down.
+
+## Provider Library Usage
 
 The `TracingEndpointProvider` object may be used by charms to manage relations with their
 trace sources. For this purposes a Tempo-like charm needs to do two things
@@ -107,7 +110,7 @@ def __init__(self, *args):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 2
+LIBPATCH = 3
 
 PYDEPS = ["pydantic"]
 

src/abstract_charm.py

@@ -100,23 +100,29 @@ def _logrotate(self) -> logrotate.LogRotate:
 
     @property
     @abc.abstractmethod
-    def _read_write_endpoint(self) -> str:
+    def _read_write_endpoints(self) -> str:
         """MySQL Router read-write endpoint"""
 
     @property
     @abc.abstractmethod
-    def _read_only_endpoint(self) -> str:
+    def _read_only_endpoints(self) -> str:
         """MySQL Router read-only endpoint"""
 
     @property
     @abc.abstractmethod
-    def _exposed_read_write_endpoint(self) -> str:
-        """The exposed read-write endpoint"""
+    def _exposed_read_write_endpoints(self) -> typing.Optional[str]:
+        """The exposed read-write endpoint.
+
+        Only defined in vm charm.
+        """
 
     @property
     @abc.abstractmethod
-    def _exposed_read_only_endpoint(self) -> str:
-        """The exposed read-only endpoint"""
+    def _exposed_read_only_endpoints(self) -> typing.Optional[str]:
+        """The exposed read-only endpoint.
+
+        Only defined in vm charm.
+        """
 
     @abc.abstractmethod
     def is_externally_accessible(self, *, event) -> typing.Optional[bool]:
@@ -125,6 +131,11 @@ def is_externally_accessible(self, *, event) -> typing.Optional[bool]:
         Only defined in vm charm to return True/False. In k8s charm, returns None.
         """
 
+    @property
+    @abc.abstractmethod
+    def _status(self) -> ops.StatusBase:
+        """Status of the charm."""
+
     @property
     def _tls_certificate_saved(self) -> bool:
         """Whether a TLS certificate is available to use"""
@@ -202,6 +213,8 @@ def _determine_app_status(self, *, event) -> ops.StatusBase:
             # (Relations should not be modified during upgrade.)
             return upgrade_status
         statuses = []
+        if self._status:
+            statuses.append(self._status)
         for endpoint in (self._database_requires, self._database_provides):
             if status := endpoint.get_status(event):
                 statuses.append(status)
@@ -236,8 +249,8 @@ def wait_until_mysql_router_ready(self, *, event) -> None:
         """
 
     @abc.abstractmethod
-    def _reconcile_node_port(self, *, event) -> None:
-        """Reconcile node port.
+    def _reconcile_service(self) -> None:
+        """Reconcile service.
 
         Only applies to Kubernetes charm
         """
@@ -249,6 +262,10 @@ def _reconcile_ports(self, *, event) -> None:
         Only applies to Machine charm
         """
 
+    @abc.abstractmethod
+    def _update_endpoints(self) -> None:
+        """Update the endpoints in the provider relation if necessary."""
+
     # =======================
     #  Handlers
     # =======================
@@ -332,23 +349,17 @@ def reconcile(self, event=None) -> None:  # noqa: C901
                     and isinstance(workload_, workload.AuthenticatedWorkload)
                     and workload_.container_ready
                 ):
-                    self._reconcile_node_port(event=event)
+                    self._reconcile_service()
                     self._database_provides.reconcile_users(
                         event=event,
-                        router_read_write_endpoint=self._read_write_endpoint,
-                        router_read_only_endpoint=self._read_only_endpoint,
-                        exposed_read_write_endpoint=self._exposed_read_write_endpoint,
-                        exposed_read_only_endpoint=self._exposed_read_only_endpoint,
+                        router_read_write_endpoints=self._read_write_endpoints,
+                        router_read_only_endpoints=self._read_only_endpoints,
+                        exposed_read_write_endpoints=self._exposed_read_write_endpoints,
+                        exposed_read_only_endpoints=self._exposed_read_only_endpoints,
                         shell=workload_.shell,
                     )
-                    # _ha_cluster only assigned a value in machine charms
-                    if self._ha_cluster:
-                        self._database_provides.update_endpoints(
-                            router_read_write_endpoint=self._read_write_endpoint,
-                            router_read_only_endpoint=self._read_only_endpoint,
-                            exposed_read_write_endpoint=self._exposed_read_write_endpoint,
-                            exposed_read_only_endpoint=self._exposed_read_only_endpoint,
-                        )
+                    self._update_endpoints()
+
             if workload_.container_ready:
                 workload_.reconcile(
                     event=event,

src/machine_charm.py

@@ -79,6 +79,10 @@ def _upgrade(self) -> typing.Optional[machine_upgrade.Upgrade]:
         except upgrade.PeerRelationNotReady:
             pass
 
+    @property
+    def _status(self) -> ops.StatusBase:
+        pass
+
     @property
     def _logrotate(self) -> machine_logrotate.LogRotate:
         return machine_logrotate.LogRotate(container_=self._container)
@@ -95,25 +99,25 @@ def host_address(self) -> str:
         return str(self.model.get_binding("juju-info").network.bind_address)
 
     @property
-    def _read_write_endpoint(self) -> str:
+    def _read_write_endpoints(self) -> str:
         return f'file://{self._container.path("/run/mysqlrouter/mysql.sock")}'
 
     @property
-    def _read_only_endpoint(self) -> str:
+    def _read_only_endpoints(self) -> str:
         return f'file://{self._container.path("/run/mysqlrouter/mysqlro.sock")}'
 
     @property
-    def _exposed_read_write_endpoint(self) -> str:
+    def _exposed_read_write_endpoints(self) -> typing.Optional[str]:
         return f"{self.host_address}:{self._READ_WRITE_PORT}"
 
     @property
-    def _exposed_read_only_endpoint(self) -> str:
+    def _exposed_read_only_endpoints(self) -> typing.Optional[str]:
         return f"{self.host_address}:{self._READ_ONLY_PORT}"
 
     def is_externally_accessible(self, *, event) -> typing.Optional[bool]:
         return self._database_provides.external_connectivity(event)
 
-    def _reconcile_node_port(self, *, event) -> None:
+    def _reconcile_service(self) -> None:
         """Only applies to Kubernetes charm, so no-op."""
         pass
 
@@ -124,6 +128,18 @@ def _reconcile_ports(self, *, event) -> None:
             ports = []
         self.unit.set_ports(*ports)
 
+    def _update_endpoints(self) -> None:
+        self._database_provides.update_endpoints(
+            router_read_write_endpoints=self._read_write_endpoints,
+            router_read_only_endpoints=self._read_only_endpoints,
+            exposed_read_write_endpoints=self._exposed_read_write_endpoints,
+            exposed_read_only_endpoints=self._exposed_read_only_endpoints,
+        )
+
+    def _wait_until_service_reconciled(self) -> None:
+        """Only applies to Kubernetes charm, so no-op."""
+        pass
+
     def wait_until_mysql_router_ready(self, *, event) -> None:
         logger.debug("Waiting until MySQL Router is ready")
         self.unit.status = ops.MaintenanceStatus("MySQL Router starting")

src/relations/database_providers_wrapper.py

@@ -45,27 +45,27 @@ def external_connectivity(self, event) -> bool:
     def update_endpoints(
         self,
         *,
-        router_read_write_endpoint: str,
-        router_read_only_endpoint: str,
-        exposed_read_write_endpoint: str,
-        exposed_read_only_endpoint: str,
+        router_read_write_endpoints: str,
+        router_read_only_endpoints: str,
+        exposed_read_write_endpoints: str,
+        exposed_read_only_endpoints: str,
     ) -> None:
         """Update the endpoints in the provides relationship databags."""
         self._database_provides.update_endpoints(
-            router_read_write_endpoint=router_read_write_endpoint,
-            router_read_only_endpoint=router_read_only_endpoint,
-            exposed_read_write_endpoint=exposed_read_write_endpoint,
-            exposed_read_only_endpoint=exposed_read_only_endpoint,
+            router_read_write_endpoints=router_read_write_endpoints,
+            router_read_only_endpoints=router_read_only_endpoints,
+            exposed_read_write_endpoints=exposed_read_write_endpoints,
+            exposed_read_only_endpoints=exposed_read_only_endpoints,
         )
 
     def reconcile_users(
         self,
         *,
         event,
-        router_read_write_endpoint: str,
-        router_read_only_endpoint: str,
-        exposed_read_write_endpoint: str,
-        exposed_read_only_endpoint: str,
+        router_read_write_endpoints: str,
+        router_read_only_endpoints: str,
+        exposed_read_write_endpoints: str,
+        exposed_read_only_endpoints: str,
         shell: mysql_shell.Shell,
     ) -> None:
         """Create requested users and delete inactive users.
@@ -76,10 +76,10 @@ def reconcile_users(
         """
         self._database_provides.reconcile_users(
             event=event,
-            router_read_write_endpoint=router_read_write_endpoint,
-            router_read_only_endpoint=router_read_only_endpoint,
-            exposed_read_write_endpoint=exposed_read_write_endpoint,
-            exposed_read_only_endpoint=exposed_read_only_endpoint,
+            router_read_write_endpoints=router_read_write_endpoints,
+            router_read_only_endpoints=router_read_only_endpoints,
+            exposed_read_write_endpoints=exposed_read_write_endpoints,
+            exposed_read_only_endpoints=exposed_read_only_endpoints,
             shell=shell,
         )
         self._deprecated_shared_db.reconcile_users(event=event, shell=shell)