[DPE-3180] Share connection info with host application

lib/charms/mongodb/v0/config_server_interface.py

@@ -35,7 +35,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 5
+LIBPATCH = 2
 
 
 class ClusterProvider(Object):
@@ -86,7 +86,6 @@ def _on_relation_changed(self, event) -> None:
         # create user and set secrets for mongos relation
         self.charm.client_relations.oversee_users(None, None)
 
-        # TODO Future PR, use secrets
         if self.charm.unit.is_leader():
             self.database_provides.update_relation_data(
                 event.relation.id,
@@ -98,6 +97,25 @@ def _on_relation_changed(self, event) -> None:
                 },
             )
 
+    def update_config_server_db(self, event):
+        """Provides related mongos applications with new config server db."""
+        if not self.pass_hook_checks(event):
+            logger.info("Skipping update_config_server_db: hook checks did not pass")
+            return
+
+        config_server_db = self.generate_config_server_db()
+
+        if not self.charm.unit.is_leader():
+            return
+
+        for relation in self.charm.model.relations[self.relation_name]:
+            self.database_provides.update_relation_data(
+                relation.id,
+                {
+                    CONFIG_SERVER_DB_KEY: config_server_db,
+                },
+            )
+
     def generate_config_server_db(self) -> str:
         """Generates the config server database for mongos to connect to."""
         replica_set_name = self.charm.app.name
@@ -121,6 +139,7 @@ def __init__(
         self.database_requires = DatabaseRequires(
             self.charm,
             relation_name=self.relation_name,
+            relations_aliases=[self.relation_name],
             database_name=self.charm.database,
             extra_user_roles=self.charm.extra_user_roles,
             additional_secret_fields=[KEYFILE_KEY],
@@ -131,11 +150,24 @@ def __init__(
             charm.on[self.relation_name].relation_created,
             self.database_requires._on_relation_created_event,
         )
+
+        self.framework.observe(
+            self.database_requires.on.database_created, self._on_database_created
+        )
         self.framework.observe(
             charm.on[self.relation_name].relation_changed, self._on_relation_changed
         )
         # TODO Future PRs handle scale down
 
+    def _on_database_created(self, event) -> None:
+        if not self.charm.unit.is_leader():
+            return
+
+        logger.info("Database and user created for mongos application")
+        self.charm.set_secret(Config.Relations.APP_SCOPE, Config.Secrets.USERNAME, event.username)
+        self.charm.set_secret(Config.Relations.APP_SCOPE, Config.Secrets.PASSWORD, event.password)
+        self.charm.share_connection_info()
+
     def _on_relation_changed(self, event) -> None:
         """Starts/restarts monogs with config server information."""
         key_file_contents = self.database_requires.fetch_relation_field(
@@ -168,7 +200,6 @@ def _on_relation_changed(self, event) -> None:
             event.defer()
             return
 
-        self.charm.share_uri()
         self.charm.unit.status = ActiveStatus()
 
     # BEGIN: helper functions

lib/charms/mongodb/v1/mongos.py

@@ -52,8 +52,11 @@ class MongosConfiguration:
     @property
     def uri(self):
         """Return URI concatenated from fields."""
-        hosts = [f"{host}:{self.port}" for host in self.hosts]
-        hosts = ",".join(hosts)
+        # mongos using Unix Domain Socket to communicate do not use port
+        if self.port:
+            self.hosts = [f"{host}:{self.port}" for host in self.hosts]
+
+        hosts = ",".join(self.hosts)
         # Auth DB should be specified while user connects to application DB.
         auth_source = ""
         if self.database != "admin":

lib/charms/mongos/v0/mongos_client_interface.py

@@ -104,6 +104,17 @@ def _on_relation_changed(self, event) -> None:
 
             self.charm.set_user_role(new_extra_user_roles)
 
+    def update_connection_info(self, config) -> None:
+        """Sends the URI to the related parent application"""
+        logger.info("Sharing connection information to host application.")
+        for relation in self.model.relations[MONGOS_RELATION_NAME]:
+            self.database_provides.set_credentials(relation.id, config.username, config.password)
+            self.database_provides.set_database(relation.id, config.database)
+            self.database_provides.set_uris(
+                relation.id,
+                config.uri,
+            )
+
 
 class MongosRequirer(Object):
     """Manage relations between the mongos router and the application on the application side."""

src/charm.py

@@ -16,7 +16,6 @@
 from charms.mongodb.v0.config_server_interface import ClusterRequirer
 from charms.mongodb.v1.users import (
     MongoDBUser,
-    OperatorUser,
 )
 
 from config import Config
@@ -234,10 +233,9 @@ def restart_mongos_service(self) -> None:
         self.stop_mongos_service()
         self.start_mongos_service()
 
-    def share_uri(self) -> None:
+    def share_connection_info(self) -> None:
         """Future PR - generate URI and give it to related app"""
-        # TODO future PR - generate different URI for data-integrator as that charm will not
-        # communicate to mongos via the Unix Domain Socket.
+        self.mongos_provider.update_connection_info(self.mongos_config)
 
     def set_user_role(self, roles: List[str]) -> None:
         """Updates the roles for the mongos user."""
@@ -297,7 +295,23 @@ def extra_user_roles(self) -> Set[str]:
     @property
     def mongos_config(self) -> MongosConfiguration:
         """Generates a MongoDBConfiguration object for mongos in the deployment of MongoDB."""
-        return self._get_mongos_config_for_user(OperatorUser, set(Config.MONGOS_SOCKET))
+        # TODO future PR - use ip addresses for hosts for data-integrator as that charm will not
+        # communicate to mongos via the Unix Domain Socket.
+        hosts = [Config.MONGOS_SOCKET_URI_FMT]
+        # mongos using Unix Domain Socket to communicate do not use port, Future PR - use port
+        # when suborinate charm of data-integrator.
+        port = None
+
+        return MongosConfiguration(
+            database=self.database,
+            username=self.get_secret(APP_SCOPE, Config.Secrets.USERNAME),
+            password=self.get_secret(APP_SCOPE, Config.Secrets.PASSWORD),
+            hosts=hosts,
+            port=port,
+            roles=self.extra_user_roles,
+            tls_external=None,  # Future PR will support TLS
+            tls_internal=None,  # Future PR will support TLS
+        )
 
     @property
     def _peers(self) -> Optional[Relation]:

src/config.py

@@ -11,6 +11,9 @@ class Config:
 
     MONGOS_PORT = 27018
     MONGOS_SOCKET = "/var/snap/charmed-mongodb/common/var/mongodb-27018.sock"
+    MONGOS_SOCKET_URI_FMT = (
+        "%2Fvar%2Fsnap%2Fcharmed-mongodb%2Fcommon%2Fvar%2Fmongodb-27018.sock"
+    )
     MONGODB_PORT = 27017
     SUBSTRATE = "vm"
     ENV_VAR_PATH = "/etc/environment"
@@ -51,5 +54,7 @@ class Secrets:
         SECRET_CACHE_LABEL = "cache"
         SECRET_KEYFILE_NAME = "keyfile"
         SECRET_INTERNAL_LABEL = "internal-secret"
+        USERNAME = "username"
+        PASSWORD = "password"
         SECRET_DELETED_LABEL = "None"
         MAX_PASSWORD_LENGTH = 4096

tests/integration/helpers.py

@@ -59,14 +59,11 @@ async def generate_mongos_uri(ops_test: OpsTest, auth: bool) -> str:
         return f"mongodb://{MONGOS_SOCKET}"
 
     secret_uri = await get_application_relation_data(
-        ops_test, "mongos", "cluster", "secret-user"
+        ops_test, "application", "mongos_proxy", "secret-user"
     )
 
     secret_data = await get_secret_data(ops_test, secret_uri)
-    username = secret_data.get("username")
-    password = secret_data.get("password")
-
-    return f"mongodb://{username}:{password}@{MONGOS_SOCKET}"
+    return secret_data.get("uris")
 
 
 async def get_secret_data(ops_test, secret_uri) -> Dict:

tests/integration/test_charm.py

@@ -17,7 +17,7 @@
 
 TEST_USER_NAME = "TestUserName1"
 TEST_USER_PWD = "Test123"
-TEST_DB_NAME = "test"
+TEST_DB_NAME = "my-test-db"
 
 
 @pytest.mark.abort_on_fail

tests/unit/test_charm.py

@@ -18,9 +18,26 @@
 
 from .helpers import patch_network_get
 
+from charms.data_platform_libs.v0.data_interfaces import DatabaseRequiresEvents
+
+CLUSTER_ALIAS = "cluster"
+
 
 class TestCharm(unittest.TestCase):
     def setUp(self, *unused):
+        try:
+            # runs before each test to delete the custom events created for the aliases. This is
+            # needed because the events are created again in the next test, which causes an error
+            # related to duplicated events.
+            delattr(DatabaseRequiresEvents, f"{CLUSTER_ALIAS}_database_created")
+            delattr(DatabaseRequiresEvents, f"{CLUSTER_ALIAS}_endpoints_changed")
+            delattr(
+                DatabaseRequiresEvents, f"{CLUSTER_ALIAS}_read_only_endpoints_changed"
+            )
+        except AttributeError:
+            # Ignore the events not existing before the first test.
+            pass
+
         self.harness = Harness(MongosOperatorCharm)
         self.addCleanup(self.harness.cleanup)
         self.harness.begin()

tests/unit/test_config_server_lib.py

@@ -10,6 +10,7 @@
 
 from .helpers import patch_network_get
 
+from charms.data_platform_libs.v0.data_interfaces import DatabaseRequiresEvents
 
 PEER_ADDR = {"private-address": "127.4.5.6"}
 REL_DATA = {
@@ -18,10 +19,25 @@
 }
 MONGOS_VAR = "MONGOS_ARGS=--configdb config-server-db/host:port"
 
+CLUSTER_ALIAS = "cluster"
+
 
 class TestConfigServerInterface(unittest.TestCase):
     @patch_network_get(private_address="1.1.1.1")
     def setUp(self):
+        try:
+            # runs before each test to delete the custom events created for the aliases. This is
+            # needed because the events are created again in the next test, which causes an error
+            # related to duplicated events.
+            delattr(DatabaseRequiresEvents, f"{CLUSTER_ALIAS}_database_created")
+            delattr(DatabaseRequiresEvents, f"{CLUSTER_ALIAS}_endpoints_changed")
+            delattr(
+                DatabaseRequiresEvents, f"{CLUSTER_ALIAS}_read_only_endpoints_changed"
+            )
+        except AttributeError:
+            # Ignore the events not existing before the first test.
+            pass
+
         self.harness = Harness(MongosOperatorCharm)
         self.harness.begin()
         self.harness.add_relation("router-peers", "router-peers")