DPE-2089 DPE-1685 DPE-2222 Use snap with ppa sources + other misc snap related improvements

src/charm.py

@@ -31,7 +31,9 @@
     ActionEvent,
     CharmBase,
     InstallEvent,
+    RelationBrokenEvent,
     RelationChangedEvent,
+    RelationCreatedEvent,
     StartEvent,
 )
 from ops.main import main
@@ -52,6 +54,7 @@
     CHARMED_MYSQLD_SERVICE,
     CLUSTER_ADMIN_PASSWORD_KEY,
     CLUSTER_ADMIN_USERNAME,
+    COS_AGENT_RELATION_NAME,
     GR_MAX_MEMBERS,
     MONITORING_PASSWORD_KEY,
     MONITORING_USERNAME,
@@ -70,7 +73,6 @@
     MySQL,
     MySQLCreateCustomMySQLDConfigError,
     MySQLDataPurgeError,
-    MySQLExporterConnectError,
     MySQLReconfigureError,
     MySQLResetRootPasswordAndStartMySQLDError,
     SnapServiceOperationError,
@@ -123,6 +125,12 @@ def __init__(self, *args):
             logs_rules_dir="./src/alert_rules/loki",
             log_slots=[f"{CHARMED_MYSQL_SNAP_NAME}:logs"],
         )
+        self.framework.observe(
+            self.on[COS_AGENT_RELATION_NAME].relation_created, self._on_cos_agent_relation_created
+        )
+        self.framework.observe(
+            self.on[COS_AGENT_RELATION_NAME].relation_broken, self._on_cos_agent_relation_broken
+        )
         self.s3_integrator = S3Requirer(self, S3_INTEGRATOR_RELATION_NAME)
         self.backups = MySQLBackups(self, self.s3_integrator)
         self.hostname_resolution = MySQLMachineHostnameResolution(self)
@@ -211,9 +219,6 @@ def _on_start(self, event: StartEvent) -> None:
         except MySQLCreateCustomMySQLDConfigError:
             self.unit.status = BlockedStatus("Failed to create custom mysqld config")
             return
-        except MySQLExporterConnectError:
-            self.unit.status = BlockedStatus("Failed to connect to MySQL exporter")
-            return
         except MySQLGetMySQLVersionError:
             logger.debug("Fail to get MySQL version")
 
@@ -381,6 +386,28 @@ def _on_update_status(self, _) -> None:
             # Set active status when primary is known
             self.app.status = ActiveStatus()
 
+    def _on_cos_agent_relation_created(self, event: RelationCreatedEvent) -> None:
+        """Handle the cos_agent relation created event.
+
+        Enable the mysqld-exporter snap service.
+        """
+        if not self._is_peer_data_set:
+            logger.debug("Charm not yet set up. Deferring")
+            event.defer()
+            return
+
+        self._mysql.connect_mysql_exporter()
+
+    def _on_cos_agent_relation_broken(self, event: RelationBrokenEvent) -> None:
+        """Handle the cos_agent relation broken event.
+
+        Disable the mysqld-exporter snap service.
+        """
+        if not self._is_peer_data_set:
+            return
+
+        self._mysql.stop_mysql_exporter()
+
     # =======================
     #  Custom Action Handlers
     # =======================
@@ -581,7 +608,6 @@ def _workload_initialise(self) -> None:
         self._mysql.configure_mysql_users()
         self._mysql.configure_instance()
         self._mysql.wait_until_mysql_connection()
-        self._mysql.connect_mysql_exporter()
         self.unit_peer_data["unit-configured"] = "True"
         self.unit_peer_data["instance-hostname"] = f"{instance_hostname()}:3306"
         if workload_version := self._mysql.get_mysql_version():

src/constants.py

@@ -32,7 +32,7 @@
 TLS_SSL_CERT_FILE = "custom-server-cert.pem"
 MYSQL_EXPORTER_PORT = "9104"
 CHARMED_MYSQL_SNAP_NAME = "charmed-mysql"
-CHARMED_MYSQL_SNAP_REVISION = 51
+CHARMED_MYSQL_SNAP_REVISION = 66  # MySQL v8.0.33
 CHARMED_MYSQLD_EXPORTER_SERVICE = "mysqld-exporter"
 CHARMED_MYSQLD_SERVICE = "mysqld"
 CHARMED_MYSQL = "charmed-mysql.mysql"
@@ -52,3 +52,4 @@
 ROOT_SYSTEM_USER = "root"
 GR_MAX_MEMBERS = 9
 HOSTNAME_DETAILS = "hostname-details"
+COS_AGENT_RELATION_NAME = "cos-agent"

src/hostname_resolution.py

@@ -135,7 +135,7 @@ def _potentially_update_etc_hosts(self, _) -> None:
         try:
             self.charm._mysql.flush_host_cache()
         except MySQLFlushHostCacheError:
-            self.unit.status = BlockedStatus("Unable to flush MySQL host cache")
+            self.charm.unit.status = BlockedStatus("Unable to flush MySQL host cache")
 
     def _remove_host_from_etc_hosts(self, event: RelationDepartedEvent) -> None:
         departing_unit_name = event.unit.name
@@ -152,4 +152,4 @@ def _remove_host_from_etc_hosts(self, event: RelationDepartedEvent) -> None:
         try:
             self.charm._mysql.flush_host_cache()
         except MySQLFlushHostCacheError:
-            self.unit.status = BlockedStatus("Unable to flush MySQL host cache")
+            self.charm.unit.status = BlockedStatus("Unable to flush MySQL host cache")

src/mysql_vm_helpers.py

@@ -166,15 +166,17 @@ def install_and_configure_mysql_dependencies() -> None:
                 mysqlsh_help_command = ["charmed-mysql.mysqlsh", "--help"]
                 subprocess.check_call(mysqlsh_help_command, stderr=subprocess.PIPE)
 
+            subprocess.run(["snap", "alias", "charmed-mysql.mysql", "mysql"], check=True)
+
             installed_by_mysql_server_file.touch(exist_ok=True)
-        except subprocess.CalledProcessError as e:
-            logger.exception("Failed to execute subprocess command", exc_info=e)
+        except subprocess.CalledProcessError:
+            logger.exception("Failed to execute subprocess command")
             raise
-        except (snap.SnapNotFoundError, snap.SnapError) as e:
-            logger.exception("Failed to install snaps", exc_info=e)
+        except (snap.SnapNotFoundError, snap.SnapError):
+            logger.exception("Failed to install snaps")
             raise
-        except Exception as e:
-            logger.exception("Encountered an unexpected exception", exc_info=e)
+        except Exception:
+            logger.exception("Encountered an unexpected exception")
             raise
 
     def create_custom_mysqld_config(self, profile: str) -> None:
@@ -495,7 +497,7 @@ def start_mysqld(self) -> None:
         )
 
         try:
-            snap_service_operation(CHARMED_MYSQL_SNAP_NAME, CHARMED_MYSQLD_SERVICE, "start", True)
+            snap_service_operation(CHARMED_MYSQL_SNAP_NAME, CHARMED_MYSQLD_SERVICE, "start")
             self.wait_until_mysql_connection()
         except (
             MySQLServiceNotRunningError,
@@ -539,11 +541,21 @@ def connect_mysql_exporter(self) -> None:
                 }
             )
             snap_service_operation(
-                CHARMED_MYSQL_SNAP_NAME, CHARMED_MYSQLD_EXPORTER_SERVICE, "start", True
+                CHARMED_MYSQL_SNAP_NAME, CHARMED_MYSQLD_EXPORTER_SERVICE, "start"
             )
         except snap.SnapError:
             logger.exception("An exception occurred when setting up mysqld-exporter.")
-            raise MySQLExporterConnectError
+            raise MySQLExporterConnectError("Error setting up mysqld-exporter")
+
+    def stop_mysql_exporter(self) -> None:
+        """Stop the mysqld exporter."""
+        try:
+            snap_service_operation(
+                CHARMED_MYSQL_SNAP_NAME, CHARMED_MYSQLD_EXPORTER_SERVICE, "stop"
+            )
+        except snap.SnapError:
+            logger.exception("An exception occurred when stopping mysqld-exporter")
+            raise MySQLExporterConnectError("Error stopping mysqld-exporter")
 
     def _run_mysqlsh_script(self, script: str, timeout=None) -> str:
         """Execute a MySQL shell script.
@@ -561,11 +573,13 @@ def _run_mysqlsh_script(self, script: str, timeout=None) -> str:
             _file.write(script)
             _file.flush()
 
-            # Specify python as this is not the default in the deb version
-            # of the mysql-shell snap
             command = [CHARMED_MYSQLSH, "--no-wizard", "--python", "-f", _file.name]
 
             try:
+                # need to change permissions since charmed-mysql.mysqlsh runs as
+                # snap_daemon
+                shutil.chown(_file.name, user="snap_daemon", group="root")
+
                 return subprocess.check_output(
                     command, stderr=subprocess.PIPE, timeout=timeout
                 ).decode("utf-8")
@@ -726,7 +740,7 @@ def instance_hostname():
         return None
 
 
-def snap_service_operation(snapname: str, service: str, operation: str, enable=False) -> bool:
+def snap_service_operation(snapname: str, service: str, operation: str) -> bool:
     """Helper function to run an operation on a snap service.
 
     Args:
@@ -752,10 +766,10 @@ def snap_service_operation(snapname: str, service: str, operation: str, enable=F
             selected_snap.restart(services=[service])
             return selected_snap.services[service]["active"]
         elif operation == "start":
-            selected_snap.start(services=[service], enable=enable)
+            selected_snap.start(services=[service], enable=True)
             return selected_snap.services[service]["active"]
         else:
-            selected_snap.stop(services=[service])
+            selected_snap.stop(services=[service], disable=True)
             return not selected_snap.services[service]["active"]
     except snap.SnapError:
         error_message = f"Failed to run snap service operation, snap={snapname}, service={service}, operation={operation}"

tests/integration/high_availability/test_replication.py

@@ -4,16 +4,19 @@
 
 
 import logging
+import time
 from pathlib import Path
 
 import pytest
 import urllib3
 import yaml
 from pytest_operator.plugin import OpsTest
+from tenacity import RetryError, Retrying, stop_after_attempt, wait_fixed
 
 from ..helpers import (
     cluster_name,
     execute_queries_on_unit,
+    fetch_credentials,
     generate_random_string,
     get_primary_unit,
     get_primary_unit_wrapper,
@@ -53,6 +56,50 @@ async def test_exporter_endpoints(ops_test: OpsTest, mysql_charm_series: str) ->
     http = urllib3.PoolManager()
 
     for unit in application.units:
+        _, output, _ = await ops_test.juju(
+            "ssh", unit.name, "sudo", "snap", "services", "charmed-mysql.mysqld-exporter"
+        )
+        assert output.split("\n")[1].split()[2] == "inactive"
+
+        return_code, _, _ = await ops_test.juju(
+            "ssh", unit.name, "sudo", "snap", "set", "charmed-mysql", "exporter.user=monitoring"
+        )
+        assert return_code == 0
+
+        monitoring_credentials = await fetch_credentials(unit, "monitoring")
+        return_code, _, _ = await ops_test.juju(
+            "ssh",
+            unit.name,
+            "sudo",
+            "snap",
+            "set",
+            "charmed-mysql",
+            f"exporter.password={monitoring_credentials['password']}",
+        )
+        assert return_code == 0
+
+        return_code, _, _ = await ops_test.juju(
+            "ssh", unit.name, "sudo", "snap", "start", "charmed-mysql.mysqld-exporter"
+        )
+        assert return_code == 0
+
+        try:
+            for attempt in Retrying(stop=stop_after_attempt(45), wait=wait_fixed(2)):
+                with attempt:
+                    _, output, _ = await ops_test.juju(
+                        "ssh",
+                        unit.name,
+                        "sudo",
+                        "snap",
+                        "services",
+                        "charmed-mysql.mysqld-exporter",
+                    )
+                    assert output.split("\n")[1].split()[2] == "active"
+        except RetryError:
+            raise Exception("Failed to start the mysqld-exporter snap service")
+
+        time.sleep(30)
+
         unit_address = await unit.get_public_address()
         mysql_exporter_url = f"http://{unit_address}:9104/metrics"
 

tests/unit/test_mysqlsh_helpers.py

@@ -49,19 +49,22 @@ def setUp(self):
 
     @patch("tempfile.NamedTemporaryFile")
     @patch("subprocess.check_output")
-    def test_run_mysqlsh_script(self, _check_output, _):
+    @patch("shutil.chown")
+    def test_run_mysqlsh_script(self, _chown, _check_output, _):
         """Test a successful execution of run_mysqlsh_script."""
         _check_output.return_value = b"stdout"
 
         self.mysql._run_mysqlsh_script("script")
 
         _check_output.assert_called_once()
+        _chown.assert_called_once()
 
     @patch("tempfile.NamedTemporaryFile")
     @patch("subprocess.check_output")
-    def test_run_mysqlsh_script_exception(self, _check_output, _):
+    @patch("shutil.chown")
+    def test_run_mysqlsh_script_exception(self, _, _check_output, __):
         """Test a failed execution of run_mysqlsh_script."""
-        _check_output.side_effect = subprocess.CalledProcessError(cmd="", returncode=-1)
+        _check_output.side_effect = subprocess.CalledProcessError(cmd="", returncode=1)
 
         with self.assertRaises(MySQLClientError):
             self.mysql._run_mysqlsh_script("script")
@@ -405,7 +408,7 @@ def test_start_mysqld(
         self.mysql.start_mysqld()
 
         _snap_service_operation.assert_called_once_with(
-            CHARMED_MYSQL_SNAP_NAME, CHARMED_MYSQLD_SERVICE, "start", True
+            CHARMED_MYSQL_SNAP_NAME, CHARMED_MYSQLD_SERVICE, "start"
         )
         _wait_until_mysql_connection.assert_called_once()
 
@@ -430,9 +433,10 @@ def test_start_mysqld_failure(
 
     @patch("pathlib.Path")
     @patch("subprocess.check_call")
+    @patch("subprocess.run")
     @patch("os.path.exists", return_value=True)
     @patch("mysql_vm_helpers.snap.SnapCache")
-    def test_install_snap(self, _cache, _path_exists, _check_call, _pathlib):
+    def test_install_snap(self, _cache, _path_exists, _run, _check_call, _pathlib):
         """Test execution of install_snap()."""
         _mysql_snap = MagicMock()
         _cache.return_value = {CHARMED_MYSQL_SNAP_NAME: _mysql_snap}
@@ -443,3 +447,4 @@ def test_install_snap(self, _cache, _path_exists, _check_call, _pathlib):
         self.mysql.install_and_configure_mysql_dependencies()
 
         _check_call.assert_called_once_with(["charmed-mysql.mysqlsh", "--help"], stderr=-1)
+        _run.assert_called_once_with(["snap", "alias", "charmed-mysql.mysql", "mysql"], check=True)