[DPE-5637, DPE-5276] Implement expose-external config option with values false (clusterip), nodeport and loadbalancer

.github/workflows/ci.yaml

@@ -96,7 +96,7 @@ jobs:
       - lint
       - unit-test
       - build
-    uses: canonical/data-platform-workflows/.github/workflows/integration_test_charm.yaml@v23.0.5
+    uses: canonical/data-platform-workflows/.github/workflows/integration_test_charm.yaml@feature/metallb
     with:
       artifact-prefix: ${{ needs.build.outputs.artifact-prefix }}
       architecture: ${{ matrix.architecture }}
@@ -106,5 +106,6 @@ jobs:
       juju-snap-channel: ${{ matrix.juju.snap_channel }}
       libjuju-version-constraint: ${{ matrix.juju.libjuju }}
       _beta_allure_report: ${{ matrix.juju.allure_on_amd64 && matrix.architecture == 'amd64' }}
+      metallb-addon: true
     permissions:
       contents: write  # Needed for Allure Report beta

config.yaml

@@ -0,0 +1,17 @@
+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+options:
+  expose-external:
+    description: |
+      String to determine how to expose the MySQLRouter externally from the Kubernetes cluster.
+      Possible values: 'false', 'nodeport', 'loadbalancer'
+    type: string
+    default: "false"
+
+  loadbalancer-extra-annotations:
+    description: |
+      A JSON string representing extra annotations for the Kubernetes service created
+      and managed by the charm.
+    type: string
+    default: "{}"

lib/charms/tempo_coordinator_k8s/v0/charm_tracing.py

@@ -269,7 +269,7 @@ 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 = 1
+LIBPATCH = 2
 
 PYDEPS = ["opentelemetry-exporter-otlp-proto-http==1.21.0"]
 
@@ -371,10 +371,6 @@ class UntraceableObjectError(TracingError):
     """Raised when an object you're attempting to instrument cannot be autoinstrumented."""
 
 
-class TLSError(TracingError):
-    """Raised when the tracing endpoint is https but we don't have a cert yet."""
-
-
 def _get_tracing_endpoint(
     tracing_endpoint_attr: str,
     charm_instance: object,
@@ -484,10 +480,15 @@ def wrap_init(self: CharmBase, framework: Framework, *args, **kwargs):
         )
 
         if tracing_endpoint.startswith("https://") and not server_cert:
-            raise TLSError(
+            logger.error(
                 "Tracing endpoint is https, but no server_cert has been passed."
-                "Please point @trace_charm to a `server_cert` attr."
+                "Please point @trace_charm to a `server_cert` attr. "
+                "This might also mean that the tracing provider is related to a "
+                "certificates provider, but this application is not (yet). "
+                "In that case, you might just have to wait a bit for the certificates "
+                "integration to settle. "
             )
+            return
 
         exporter = OTLPSpanExporter(
             endpoint=tracing_endpoint,

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 = 1
+LIBPATCH = 3
 
 PYDEPS = ["pydantic"]
 
@@ -985,11 +988,16 @@ def charm_tracing_config(
     is_https = endpoint.startswith("https://")
 
     if is_https:
-        if cert_path is None:
-            raise TracingError("Cannot send traces to an https endpoint without a certificate.")
-        elif not Path(cert_path).exists():
-            # if endpoint is https BUT we don't have a server_cert yet:
-            # disable charm tracing until we do to prevent tls errors
+        if cert_path is None or not Path(cert_path).exists():
+            # disable charm tracing until we obtain a cert to prevent tls errors
+            logger.error(
+                "Tracing endpoint is https, but no server_cert has been passed."
+                "Please point @trace_charm to a `server_cert` attr. "
+                "This might also mean that the tracing provider is related to a "
+                "certificates provider, but this application is not (yet). "
+                "In that case, you might just have to wait a bit for the certificates "
+                "integration to settle. "
+            )
             return None, None
         return endpoint, str(cert_path)
     else:

pyproject.toml

@@ -60,7 +60,6 @@ tenacity = "^8.5.0"
 allure-pytest = "^2.13.5"
 allure-pytest-collection-report = {git = "https://github.com/canonical/data-platform-workflows", tag = "v23.0.2", subdirectory = "python/pytest_plugins/allure_pytest_collection_report"}
 
-
 [tool.coverage.run]
 branch = true
 

src/abstract_charm.py

@@ -48,6 +48,7 @@ def __init__(self, *args) -> None:
         self._database_requires = relations.database_requires.RelationEndpoint(self)
         self._database_provides = relations.database_provides.RelationEndpoint(self)
         self._cos_relation = relations.cos.COSRelation(self, self._container)
+        self._ha_cluster = None
         self.framework.observe(self.on.update_status, self.reconcile)
         self.framework.observe(
             self.on[upgrade.PEER_RELATION_ENDPOINT_NAME].relation_changed, self.reconcile
@@ -99,23 +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_endpoint(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_endpoint(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]:
@@ -124,6 +131,14 @@ 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.
+
+        Only applies to Kubernetes charm
+        """
+
     @property
     def _tls_certificate_saved(self) -> bool:
         """Whether a TLS certificate is available to use"""
@@ -201,6 +216,8 @@ 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)
@@ -212,6 +229,9 @@ def _determine_unit_status(self, *, event) -> ops.StatusBase:
         workload_status = self.get_workload(event=event).status
         if self._upgrade:
             statuses.append(self._upgrade.get_unit_juju_status(workload_status=workload_status))
+        # only in machine charms
+        if self._ha_cluster:
+            statuses.append(self._ha_cluster.get_unit_juju_status())
         statuses.append(workload_status)
         return self._prioritize_statuses(statuses)
 
@@ -232,19 +252,30 @@ 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
         """
 
+    def _check_service_connectivity(self) -> bool:
+        """Check if the service is available (connectable with a socket).
+
+        Returns false if Machine charm. Overridden in Kubernetes charm.
+        """
+        return False
+
     @abc.abstractmethod
     def _reconcile_ports(self, *, event) -> None:
         """Reconcile exposed ports.
 
         Only applies to Machine charm
         """
 
+    @abc.abstractmethod
+    def _update_endpoints(self) -> None:
+        """Update the endpoints in the provider relation if necessary."""
+
     # =======================
     #  Handlers
     # =======================
@@ -311,6 +342,10 @@ def reconcile(self, event=None) -> None:  # noqa: C901
             f"{self._cos_relation.is_relation_breaking(event)=}"
         )
 
+        # only in machine charms
+        if self._ha_cluster:
+            self._ha_cluster.set_vip(self.config.get("vip"))
+
         try:
             if self._unit_lifecycle.authorized_leader:
                 if self._database_requires.is_relation_breaking(event):
@@ -324,15 +359,17 @@ 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,
+                        router_read_write_endpoints=self._read_write_endpoints,
+                        router_read_only_endpoints=self._read_only_endpoints,
                         exposed_read_write_endpoint=self._exposed_read_write_endpoint,
                         exposed_read_only_endpoint=self._exposed_read_only_endpoint,
                         shell=workload_.shell,
                     )
+                    self._update_endpoints()
+
             if workload_.container_ready:
                 workload_.reconcile(
                     event=event,