Update relation information on scale up\scale down (#144)

* Update relation informaion on scale up\scale down

Add integration tests for releations

Fixes #111

* WIP: intergration tests

* Add integration tests for relations

* Fix lint issues

* Address review comments

* Reformat file

* Removed custom get_info_from_mongo_connection_string

methond in favor of from pymongo.uri_parser import parse_uri

* Removed extra blank lines

src/charm.py

@@ -53,6 +53,7 @@
 UNIX_USER = "mongodb"
 UNIX_GROUP = "mongodb"
 MONGODB_EXPORTER_PORT = 9216
+REL_NAME = "database"
 
 
 class MongoDBCharm(CharmBase):
@@ -253,13 +254,30 @@ def _reconfigure(self, event) -> None:
                             event.defer()
                             return
                     mongo.add_replset_member(member)
+
+                # app relations should be made aware of the new set of hosts
+                self._update_app_relation_data(mongo.get_users())
             except NotReadyError:
                 logger.info("Deferring reconfigure: another member doing sync right now")
                 event.defer()
             except PyMongoError as e:
                 logger.info("Deferring reconfigure: error=%r", e)
                 event.defer()
 
+    def _update_app_relation_data(self, database_users):
+        """Helper function to update application relation data."""
+        for relation in self.model.relations[REL_NAME]:
+            username = self.client_relations._get_username_from_relation_id(relation.id)
+            password = relation.data[self.app]["password"]
+            if username in database_users:
+                config = self.client_relations._get_config(username, password)
+                relation.data[self.app].update(
+                    {
+                        "endpoints": ",".join(config.hosts),
+                        "uris": config.uri,
+                    }
+                )
+
     @property
     def _mongodb_exporter_layer(self) -> Layer:
         """Returns a Pebble configuration layer for mongod."""

tests/integration/ha_tests/helpers.py

@@ -1,6 +1,7 @@
 # Copyright 2023 Canonical Ltd.
 # See LICENSE file for licensing details.
 
+import logging
 import os
 import string
 import subprocess
@@ -34,9 +35,11 @@
 TIMEOUT = 15 * 60
 TEST_DB = "continuous_writes_database"
 TEST_COLLECTION = "test_collection"
-ANOTHER_DATABASE_APP_NAME = "another-database-a"
+ANOTHER_DATABASE_APP_NAME = "another-database"
 EXCLUDED_APPS = [ANOTHER_DATABASE_APP_NAME]
 
+logger = logging.getLogger(__name__)
+
 mongodb_charm, application_charm = None, None
 
 
@@ -311,17 +314,25 @@ async def mongod_ready(ops_test: OpsTest, unit: int) -> bool:
     return True
 
 
-async def get_replica_set_primary(ops_test: OpsTest, excluded: List[str] = []) -> Optional[Unit]:
+async def get_replica_set_primary(
+    ops_test: OpsTest, excluded: List[str] = [], application_name=APP_NAME
+) -> Optional[Unit]:
     """Returns the primary unit name based no the replica set host."""
     with await get_mongo_client(ops_test, excluded) as client:
         data = client.admin.command("replSetGetStatus")
-
     unit_name = host_to_unit(primary_host(data))
+
     if unit_name:
-        mongodb_name = await get_application_name(ops_test, APP_NAME)
+        mongodb_name = await get_application_name(ops_test, application_name)
         for unit in ops_test.model.applications[mongodb_name].units:
+            logger.info(
+                f"Unit name: {unit.name}. Target unit name: {unit_name}, {unit.name == unit_name}"
+            )
             if unit.name == unit_name:
                 return unit
+        logger.error(
+            f"Target unit name {unit_name} not found in {ops_test.model.applications[mongodb_name].units}"
+        )
 
 
 async def count_primaries(ops_test: OpsTest) -> int:

tests/integration/helpers.py

@@ -96,13 +96,19 @@ async def run_mongo_op(
     mongo_uri: str = None,
     suffix: str = "",
     expecting_output: bool = True,
+    stringify: bool = True,
+    ignore_errors: bool = False,
 ) -> SimpleNamespace():
     """Runs provided MongoDB operation in a separate container."""
     if mongo_uri is None:
         mongo_uri = await mongodb_uri(ops_test)
 
-    mongo_cmd = f"mongo --quiet --eval 'JSON.stringify({mongo_op})' {mongo_uri}{suffix}"
+    if stringify:
+        mongo_cmd = f"mongo --quiet --eval 'JSON.stringify({mongo_op})' {mongo_uri}{suffix}"
+    else:
+        mongo_cmd = f"mongo --quiet --eval '{mongo_op}' {mongo_uri}{suffix}"
 
+    logger.info("Running mongo command: %r", mongo_cmd)
     kubectl_cmd = (
         "microk8s",
         "kubectl",
@@ -127,6 +133,11 @@ async def run_mongo_op(
     if ret_code != 0:
         logger.error("code %r; stdout %r; stderr: %r", ret_code, stdout, stderr)
         output.failed = True
+        output.data = {
+            "code": ret_code,
+            "stdout": stdout,
+            "stderr": stderr,
+        }
         return output
 
     output.succeeded = True
@@ -136,12 +147,14 @@ async def run_mongo_op(
         except Exception:
             logger.error(
                 "Could not serialize the output into json.{}{}".format(
-                    f"\n\tOut: {stdout}" if stdout else "",
-                    f"\n\tErr: {stderr}" if stderr else "",
+                    f"\n\tSTDOUT:\n\t {stdout}" if stdout else "",
+                    f"\n\tSTDERR:\n\t {stderr}" if stderr else "",
                 )
             )
-            raise
-
+            if not ignore_errors:
+                raise
+            else:
+                output.data = stdout
     return output
 
 

tests/integration/relation_tests/__init__.py

@@ -0,0 +1,2 @@
+# Copyright 2023 Canonical Ltd.
+# See LICENSE file for licensing details.

tests/integration/relation_tests/application-charm/charmcraft.yaml

@@ -0,0 +1,11 @@
+# Copyright 2023 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+type: charm
+bases:
+  - build-on:
+      - name: "ubuntu"
+        channel: "22.04"
+    run-on:
+      - name: "ubuntu"
+        channel: "22.04"