DPE-1789 Add logrotation via cron (#80)

## Issue
We are not rotating the mysqlrouter logs currently

## Solution
Rotate the logs using a cron (according to spec DA043) similar to the
log rotation in mysql vm charm.
- Run a cron every minute that runs `logrotate` with a specified config
file for mysqlrouter
- Add integration test for logrotation
- Fix broken unit tests

---------

Co-authored-by: Carl Csaposs <[email protected]>

Author: shayancanonical

.github/workflows/ci.yaml

@@ -64,8 +64,6 @@ jobs:
   build:
     name: Build charms
     uses: canonical/data-platform-workflows/.github/workflows/[email protected]
-    with:
-      charmcraft-snap-revision: 1349  # version 2.3.0
     permissions:
       actions: write  # Needed to manage GitHub Actions cache
 

.github/workflows/release.yaml

@@ -18,8 +18,6 @@ jobs:
   build:
     name: Build charm
     uses: canonical/data-platform-workflows/.github/workflows/[email protected]
-    with:
-      charmcraft-snap-revision: 1349  # version 2.3.0
 
   release:
     name: Release charm

charmcraft.yaml

@@ -28,5 +28,3 @@ parts:
           exit 1
       fi
     charm-entrypoint: src/machine_charm.py
-    charm-binary-python-packages:
-      - mysql-connector-python==8.0.32

poetry.lock

@@ -12,6 +12,7 @@ authors = []
 python = "^3.8.1"  # ^3.8.1 required by flake8
 ops = "^2.6.0"
 tenacity = "^8.2.3"
+jinja2 = "^3.1.2"
 
 [tool.poetry.group.charm-libs.dependencies]
 # data_platform_libs/v0/data_interfaces.py
@@ -51,6 +52,7 @@ pytest-operator-cache = {git = "https://github.com/canonical/data-platform-workf
 pytest-operator-groups = {git = "https://github.com/canonical/data-platform-workflows", tag = "v5.0.1", subdirectory = "python/pytest_plugins/pytest_operator_groups"}
 juju = "^2.9.44.0"
 mysql-connector-python = "~8.0.33"
+tenacity = "^8.2.2"
 
 
 [tool.coverage.run]

pyproject.toml

@@ -13,6 +13,7 @@
 
 import container
 import lifecycle
+import logrotate
 import relations.database_provides
 import relations.database_requires
 import workload
@@ -59,6 +60,11 @@ def _tls_certificate_saved(self) -> bool:
     def _container(self) -> container.Container:
         """Workload container (snap or ROCK)"""
 
+    @property
+    @abc.abstractmethod
+    def _logrotate(self) -> logrotate.LogRotate:
+        """logrotate"""
+
     @property
     @abc.abstractmethod
     def _read_write_endpoint(self) -> str:
@@ -74,10 +80,11 @@ def get_workload(self, *, event):
         if connection_info := self._database_requires.get_connection_info(event=event):
             return self._authenticated_workload_type(
                 container_=self._container,
+                logrotate_=self._logrotate,
                 connection_info=connection_info,
                 charm_=self,
             )
-        return self._workload_type(container_=self._container)
+        return self._workload_type(container_=self._container, logrotate_=self._logrotate)
 
     @staticmethod
     # TODO python3.10 min version: Use `list` instead of `typing.List`

src/abstract_charm.py

@@ -0,0 +1,26 @@
+# Copyright 2023 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+"""logrotate
+
+https://manpages.ubuntu.com/manpages/jammy/man8/logrotate.8.html
+"""
+
+import abc
+
+import container
+
+
+class LogRotate(abc.ABC):
+    """logrotate"""
+
+    def __init__(self, *, container_: container.Container):
+        self._container = container_
+
+    @abc.abstractmethod
+    def enable(self) -> None:
+        """Enable logrotate."""
+
+    @abc.abstractmethod
+    def disable(self) -> None:
+        """Disable logrotate."""

src/logrotate.py

@@ -12,6 +12,7 @@
 import ops
 
 import abstract_charm
+import machine_logrotate
 import relations.database_providers_wrapper
 import snap
 import socket_workload
@@ -44,6 +45,10 @@ def _subordinate_relation_endpoint_names(self) -> typing.Optional[typing.Iterabl
     def _container(self) -> snap.Snap:
         return snap.Snap()
 
+    @property
+    def _logrotate(self) -> machine_logrotate.LogRotate:
+        return machine_logrotate.LogRotate(container_=self._container)
+
     @property
     def _read_write_endpoint(self) -> str:
         return f'file://{self._container.path("/run/mysqlrouter/mysql.sock")}'

src/machine_charm.py

@@ -0,0 +1,56 @@
+# Copyright 2023 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+"""logrotate cron configuration"""
+
+import logging
+
+import jinja2
+
+import container
+import logrotate
+
+logger = logging.getLogger(__name__)
+
+CHARMED_MYSQL_COMMON_DIRECTORY = "/var/snap/charmed-mysql/common"
+SYSTEM_USER = "snap_daemon"
+ROOT_USER = "root"
+
+
+class LogRotate(logrotate.LogRotate):
+    """logrotate cron configuration"""
+
+    def __init__(self, *, container_: container.Container):
+        super().__init__(container_=container_)
+        self._logrotate_config = self._container.path("/etc/logrotate.d/flush_mysqlrouter_logs")
+        self._cron_file = self._container.path("/etc/cron.d/flush_mysqlrouter_logs")
+
+    def enable(self) -> None:
+        logger.debug("Creating logrotate config file")
+
+        template = jinja2.Template(self._container.path("templates/logrotate.j2").read_text())
+
+        log_file_path = self._container.path("/var/log/mysqlrouter/mysqlrouter.log")
+        rendered = template.render(
+            log_file_path=str(log_file_path),
+            system_user=SYSTEM_USER,
+        )
+        self._logrotate_config.write_text(rendered)
+
+        logger.debug("Created logrotate config file")
+        logger.debug("Adding cron job for logrotate")
+
+        # cron needs the file to be owned by root
+        self._cron_file.write_text(
+            "* * * * * snap_daemon logrotate -f -s /tmp/logrotate.status /etc/logrotate.d/flush_mysqlrouter_logs\n\n",
+            user=ROOT_USER,
+            group=ROOT_USER,
+        )
+
+        logger.debug("Added cron job for logrotate")
+
+    def disable(self) -> None:
+        logger.debug("Removing cron job for log rotation of mysqlrouter")
+        self._logrotate_config.unlink()
+        self._cron_file.unlink()
+        logger.debug("Removed cron job for log rotation of mysqlrouter")

src/machine_logrotate.py

@@ -20,6 +20,7 @@
 _SNAP_NAME = "charmed-mysql"
 _REVISION = "69"  # v8.0.34
 _snap = snap_lib.SnapCache()[_SNAP_NAME]
+_UNIX_USERNAME = "snap_daemon"
 
 
 def install(*, unit: ops.Unit):
@@ -56,8 +57,6 @@ def uninstall():
 
 
 class _Path(pathlib.PosixPath, container.Path):
-    _UNIX_USERNAME = "snap_daemon"
-
     def __new__(cls, *args, **kwargs):
         path = super().__new__(cls, *args, **kwargs)
         if args and isinstance(args[0], cls) and (parent_ := args[0]._container_parent):
@@ -67,7 +66,9 @@ def __new__(cls, *args, **kwargs):
                 "/var/lib/mysqlrouter"
             ):
                 parent = f"/var/snap/{_SNAP_NAME}/current"
-            elif str(path).startswith("/run"):
+            elif str(path).startswith("/run/mysqlrouter") or str(path).startswith(
+                "/var/log/mysqlrouter"
+            ):
                 parent = f"/var/snap/{_SNAP_NAME}/common"
             elif str(path).startswith("/tmp"):
                 parent = f"/tmp/snap-private-tmp/snap.{_SNAP_NAME}"
@@ -94,14 +95,22 @@ def relative_to_container(self) -> pathlib.PurePosixPath:
     def read_text(self, encoding="utf-8", *args, **kwargs) -> str:
         return super().read_text(encoding, *args, **kwargs)
 
-    def write_text(self, data: str, encoding="utf-8", *args, **kwargs):
+    def write_text(
+        self,
+        data: str,
+        encoding="utf-8",
+        *args,
+        user=_UNIX_USERNAME,
+        group=_UNIX_USERNAME,
+        **kwargs,
+    ):
         return_value = super().write_text(data, encoding, *args, **kwargs)
-        shutil.chown(self, user=self._UNIX_USERNAME, group=self._UNIX_USERNAME)
+        shutil.chown(self, user=user, group=group)
         return return_value
 
     def mkdir(self, *args, **kwargs) -> None:
         super().mkdir(*args, **kwargs)
-        shutil.chown(self, user=self._UNIX_USERNAME, group=self._UNIX_USERNAME)
+        shutil.chown(self, user=_UNIX_USERNAME, group=_UNIX_USERNAME)
 
     def rmtree(self):
         shutil.rmtree(self)