src/charm.py

@@ -9,12 +9,14 @@
 import logging
 import socket
 
-import charms.operator_libs_linux.v2.snap as snap
+import charms.operator_libs_linux.v2.snap as snap_lib
 import ops
 import tenacity
 
 import relations.database_provides
 import relations.database_requires
+import snap
+import socket_workload
 import workload
 
 logger = logging.getLogger(__name__)
@@ -37,17 +39,19 @@ def __init__(self, *args) -> None:
 
     def get_workload(self, *, event):
         """MySQL Router workload"""
+        container = snap.Snap()
         if connection_info := self.database_requires.get_connection_info(event=event):
-            return workload.AuthenticatedWorkload(
-                _connection_info=connection_info,
-                _charm=self,
+            return socket_workload.AuthenticatedSocketWorkload(
+                container_=container,
+                connection_info=connection_info,
+                charm_=self,
             )
-        return workload.Workload()
+        return socket_workload.SocketWorkload(container_=container)
 
     @property
     def _endpoint(self) -> str:
         """K8s endpoint for MySQL Router"""
-        # TODO: socket file
+        # TODO: remove
         # Example: mysql-router-k8s.my-model.svc.cluster.local
         return "foo"
         # return f"{self.app.name}.{self.model_service_domain}"
@@ -156,21 +160,21 @@ def _on_install(self, _) -> None:
         # TODO set workload version
         _SNAP_NAME = "charmed-mysql"
         _SNAP_REVISION = "51"
-        mysql_snap = snap.SnapCache()[_SNAP_NAME]
+        mysql_snap = snap_lib.SnapCache()[_SNAP_NAME]
         if mysql_snap.present:
             logger.error(f"{_SNAP_NAME} snap already installed on machine. Installation aborted")
             raise Exception(f"Multiple {_SNAP_NAME} snap installs not supported on one machine")
         logger.debug(f"Installing {_SNAP_NAME=}, {_SNAP_REVISION=}")
         # TODO: set status
         # TODO catch/retry on error?
-        mysql_snap.ensure(snap.SnapState.Present, revision=_SNAP_REVISION)
+        mysql_snap.ensure(snap_lib.SnapState.Present, revision=_SNAP_REVISION)
         logger.debug(f"Installed {_SNAP_NAME=}, {_SNAP_REVISION=}")
         self.unit.set_workload_version(self.get_workload(event=None).version)
 
     def _on_remove(self, _) -> None:
         _SNAP_NAME = "charmed-mysql"
-        mysql_snap = snap.SnapCache()[_SNAP_NAME]
-        mysql_snap.ensure(snap.SnapState.Absent)
+        mysql_snap = snap_lib.SnapCache()[_SNAP_NAME]
+        mysql_snap.ensure(snap_lib.SnapState.Absent)
 
     def _on_start(self, _) -> None:
         # Set status on first start if no relations active

src/mysql_shell.py

@@ -9,59 +9,60 @@
 import dataclasses
 import json
 import logging
-import pathlib
 import secrets
 import string
-import subprocess
+import typing
+
+import container
 
 _PASSWORD_LENGTH = 24
 logger = logging.getLogger(__name__)
 
 
+# TODO python3.10 min version: Add `(kw_only=True)`
+@dataclasses.dataclass
+class RouterUserInformation:
+    """MySQL Router user information"""
+
+    username: str
+    router_id: str
+
+
 # TODO python3.10 min version: Add `(kw_only=True)`
 @dataclasses.dataclass
 class Shell:
     """MySQL Shell connected to MySQL cluster"""
 
+    _container: container.Container
     username: str
     _password: str
     _host: str
     _port: str
 
-    _TEMPORARY_SCRIPT_FILE = pathlib.Path("/tmp/snap-private-tmp/snap.charmed-mysql/tmp/script.py")
-
-    def _run_commands(self, commands: list[str]) -> None:
+    def _run_commands(self, commands: list[str]) -> str:
         """Connect to MySQL cluster and run commands."""
         # Redact password from log
         logged_commands = commands.copy()
-        # Password is still logged on user creation
+        # TODO: Password is still logged on user creation
         logged_commands.insert(
             0, f"shell.connect('{self.username}:***@{self._host}:{self._port}')"
         )
 
         commands.insert(
             0, f"shell.connect('{self.username}:{self._password}@{self._host}:{self._port}')"
         )
-        with open(self._TEMPORARY_SCRIPT_FILE, "w") as file:
-            file.write("\n".join(commands))
+        temporary_script_file = self._container.path("/tmp/script.py")
+        temporary_script_file.write_text("\n".join(commands))
         try:
-            subprocess.run(
-                [
-                    "charmed-mysql.mysqlsh",
-                    "--no-wizard",
-                    "--python",
-                    "--file",
-                    "/tmp/script.py",
-                ],
-                capture_output=True,
-                check=True,
-                encoding="utf-8",
+            output = self._container.run_mysql_shell(
+                ["--no-wizard", "--python", "--file", temporary_script_file]
             )
-        except subprocess.CalledProcessError as e:
+        except container.CalledProcessError as e:
             logger.exception(f"Failed to run {logged_commands=}\nstderr:\n{e.stderr}\n")
             raise
         finally:
-            self._TEMPORARY_SCRIPT_FILE.unlink()
+            temporary_script_file.unlink()
+        return output
 
     def _run_sql(self, sql_statements: list[str]) -> None:
         """Connect to MySQL cluster and execute SQL."""
@@ -114,6 +115,48 @@ def add_attributes_to_mysql_router_user(
         self._run_sql([f"ALTER USER `{username}` ATTRIBUTE '{attributes}'"])
         logger.debug(f"Added {attributes=} to {username=}")
 
+    def get_mysql_router_user_for_unit(
+        self, unit_name: str
+    ) -> typing.Optional[RouterUserInformation]:
+        """Get MySQL Router user created by a previous instance of the unit.
+
+        Get username & router ID attribute.
+
+        Before container restart, the charm does not have an opportunity to delete the MySQL
+        Router user or cluster metadata created during MySQL Router bootstrap. After container
+        restart, the user and cluster metadata should be deleted before bootstrapping MySQL Router
+        again.
+        """
+        logger.debug(f"Getting MySQL Router user for {unit_name=}")
+        rows = json.loads(
+            self._run_commands(
+                [
+                    f"result = session.run_sql(\"SELECT USER, ATTRIBUTE->>'$.router_id' FROM INFORMATION_SCHEMA.USER_ATTRIBUTES WHERE ATTRIBUTE->'$.created_by_user'='{self.username}' AND ATTRIBUTE->'$.created_by_juju_unit'='{unit_name}'\")",
+                    "print(result.fetch_all())",
+                ]
+            )
+        )
+        if not rows:
+            logger.debug(f"No MySQL Router user found for {unit_name=}")
+            return
+        assert len(rows) == 1
+        username, router_id = rows[0]
+        user_info = RouterUserInformation(username=username, router_id=router_id)
+        logger.debug(f"MySQL Router user found for {unit_name=}: {user_info}")
+        return user_info
+
+    def remove_router_from_cluster_metadata(self, router_id: str) -> None:
+        """Remove MySQL Router from InnoDB Cluster metadata.
+
+        On container restart, MySQL Router bootstrap will fail without `--force` if cluster
+        metadata already exists for the router ID.
+        """
+        logger.debug(f"Removing {router_id=} from cluster metadata")
+        self._run_commands(
+            ["cluster = dba.get_cluster()", f'cluster.remove_router_metadata("{router_id}")']
+        )
+        logger.debug(f"Removed {router_id=} from cluster metadata")
+
     def delete_user(self, username: str) -> None:
         """Delete user."""
         logger.debug(f"Deleting {username=}")

src/relations/database_provides.py

@@ -75,7 +75,7 @@ def __init__(
     def _set_databag(self, *, username: str, password: str, router_endpoint: str) -> None:
         """Share connection information with application charm."""
         # TODO: remove `file://`?
-        # TODO: https://dev.mysql.com/doc/refman/8.0/en/connecting-using-uri-or-key-value-pairs.html#connecting-using-uri
+        # TODO: get socket path from variable
         read_write_endpoint = (
             "file:///var/snap/charmed-mysql/common/var/run/mysqlrouter/mysql.sock"
         )

src/snap.py

@@ -6,7 +6,8 @@
 
 import container
 
-_UNIX_USERNAME = "foo"
+_UNIX_USERNAME = None  # TODO
+_SNAP_NAME = "charmed-mysql"
 
 
 class _SnapPath(pathlib.PosixPath):
@@ -15,9 +16,11 @@ def __new__(cls, *args, **kwargs):
         if str(path).startswith("/etc/mysqlrouter") or str(path).startswith(
             "/var/lib/mysqlrouter"
         ):
-            parent = "/var/snap/charmed-mysql/current"
+            parent = f"/var/snap/{_SNAP_NAME}/current"
         elif str(path).startswith("/run"):
-            parent = "/var/snap/charmed-mysql/common"
+            parent = f"/var/snap/{_SNAP_NAME}/common"
+        elif str(path).startswith("/tmp"):
+            parent = f"/tmp/snap-private-tmp/snap.{_SNAP_NAME}"
         else:
             return path
         assert str(path).startswith("/")
@@ -44,22 +47,21 @@ def rmtree(self):
 
 class Snap(container.Container):
     UNIX_USERNAME = _UNIX_USERNAME
-    _SNAP_NAME = "charmed-mysql"
     _SNAP_REVISION = "51"
     _SERVICE_NAME = "mysqlrouter-service"
 
     def __init__(self) -> None:
         super().__init__(
-            mysql_router_command=f"{self._SNAP_NAME}.mysqlrouter",
-            mysql_shell_command=f"{self._SNAP_NAME}.mysqlsh",
+            mysql_router_command=f"{_SNAP_NAME}.mysqlrouter",
+            mysql_shell_command=f"{_SNAP_NAME}.mysqlsh",
         )
 
     def ready(self) -> bool:
         return True
 
     @property
     def _snap(self) -> snap_lib.Snap:
-        return snap_lib.SnapCache()[self._SNAP_NAME]
+        return snap_lib.SnapCache()[_SNAP_NAME]
 
     @property
     def mysql_router_service_enabled(self) -> bool:

src/socket_workload.py

@@ -5,6 +5,7 @@
 import workload
 
 
+# TODO: rename to Workload?
 class SocketWorkload(workload.Workload):
     pass