Create a charm action to run wp core update db after a wordpress upgr…

…ade (#235)

* Added the `update-database` action. I need feedback and advice on what kind of tests I need to write.

* Added  `dry-run` parameter

* Wrote unit tests for `update-database` action

* Removed blank lines after docstring

* Fixed error message if action fails.

* Making sure stderr exists and a str in action fail

* Fixed number of commands in mock

* Updated uni tests

* Removed unnecessary else

* Better debug and auto update-database when charm upgrades

* Fix forgotten docstring

* Removed empty line after docstring.

* Better handle parameters get

* Fixed docstring

* Make linter happy.

* Wrote how-to document for charm update

* Add final new line

* Removed update function from on-upgrade event, private function rearrangement, function re-order.

* Document updates

* Initialized test fail parameter and updated docstring

* Fixed private function returning wrong type.

* Fixed mock return results for database update

* Happy linter happy life

* Better documentation

actions.yaml

@@ -11,3 +11,11 @@ rotate-wordpress-secrets:
     auth_key, auth_salt, logged_in_key, logged_in_salt, nonce_key, nonce_salt, secure_auth_key,
     secure_auth_salt.
     Users will be forced to log in again. This might be useful under security breach circumstances.
+update-database:
+  description: >
+    After upgrading WordPress to a new version it is typically necessary to run 'wp core update-db'
+    to migrate the database schema. This action does exactly that.
+  params:
+    dry-run:
+      type: boolean
+      description: Runs the 'wp core update-db --dry-run' command.

docs/how-to/upgrade-wordpress-charm.md

@@ -0,0 +1,20 @@
+# How to upgrade WordPress Charm
+
+Before updating the Charm you need to backup the database using MySQL charm's `create-backup` action.
+
+```
+juju run mysql/leader create-backup
+```
+Additional info can be found about backup in [the MySQL documentation](https://charmhub.io/mysql/docs/h-create-and-list-backups)
+
+Then you can upgrade the WordPress Charm.
+
+```
+juju refresh wordpress-k8s
+```
+
+After upgrading the WordPress Charm you need to update the database schema.
+
+```
+juju run wordpress-k8s/0 update-database
+```

src/charm.py

@@ -182,6 +182,7 @@ def __init__(self, *args, **kwargs):
         self.framework.observe(
             self.on.rotate_wordpress_secrets_action, self._on_rotate_wordpress_secrets_action
         )
+        self.framework.observe(self.on.update_database_action, self._on_update_database_action)
 
         self.framework.observe(self.on.leader_elected, self._setup_replica_data)
         self.framework.observe(self.on.uploads_storage_attached, self._reconciliation)
@@ -267,6 +268,49 @@ def _on_rotate_wordpress_secrets_action(self, event: ActionEvent):
         self._reconciliation(event)
         event.set_results({"result": "ok"})
 
+    def _on_update_database_action(self, event: ActionEvent):
+        """Handle the update-database action.
+
+        This action is to upgrade the database schema after the WordPress version is upgraded.
+
+        Args:
+            event: Used for returning result or failure of action.
+        """
+        logger.info("Starting Database update process.")
+        result = self._update_database(bool(event.params.get("dry-run")))
+        if result.success:
+            logger.info("Finished Database update process.")
+            event.set_results({"result": result.message})
+            return
+        logger.error("Failed to update database schema: %s", result.message)
+        event.fail(result.message)
+
+    def _update_database(self, dry_run: bool = False) -> types_.ExecResult:
+        """Update database.
+
+        Args:
+            dry_run (bool, optional): Runs update as a dry-run, useful to check
+            if update is necessary without doing the update. Defaults to False.
+
+        Returns:
+            Execution result.
+        """
+        cmd = ["wp", "core", "update-db"]
+        if dry_run:
+            cmd.append("--dry-run")
+
+        result = self._run_wp_cli(cmd, timeout=600)
+        if result.return_code != 0:
+            return types_.ExecResult(
+                success=False,
+                result=None,
+                message=str(result.stderr) if result.stderr else "Database update failed",
+            )
+        logger.info("Finished Database update process.")
+        return types_.ExecResult(
+            success=True, result=None, message=str(result.stdout) if result.stdout else "ok"
+        )
+
     @staticmethod
     def _wordpress_secret_key_fields():
         """Field names of secrets required for instantiation of WordPress.

tests/unit/test_charm.py

@@ -476,6 +476,47 @@ def test_rotate_wordpress_secrets(
     action_event_mock.fail.assert_not_called()
 
 
+def test_update_database(
+    patch,
+    harness: ops.testing.Harness,
+    action_event_mock: unittest.mock.MagicMock,
+):
+    """
+    arrange: after charm is initialized and database ready.
+    act: run update-database action.
+    assert: update-database action should success and return "ok".
+    """
+    harness.set_can_connect(harness.model.unit.containers["wordpress"], True)
+    harness.begin_with_initial_hooks()
+    patch.container._fail_wp_update_database = False
+    charm: WordpressCharm = typing.cast(WordpressCharm, harness.charm)
+    charm._on_update_database_action(action_event_mock)
+
+    action_event_mock.set_results.assert_called_once_with({"result": "ok"})
+    action_event_mock.fail.assert_not_called()
+
+
+def test_update_database_fail(
+    patch,
+    harness: ops.testing.Harness,
+    action_event_mock: unittest.mock.MagicMock,
+):
+    """
+    arrange: after charm is initialized and database is mocked to fail.
+    act: run update-database action.
+    assert: update-database action should fail.
+    """
+    harness.set_can_connect(harness.model.unit.containers["wordpress"], True)
+    harness.begin_with_initial_hooks()
+    patch.container._fail_wp_update_database = True
+    charm: WordpressCharm = typing.cast(WordpressCharm, harness.charm)
+    action_event_mock.configure_mock()
+    charm._on_update_database_action(action_event_mock)
+
+    action_event_mock.set_results.assert_not_called()
+    action_event_mock.fail.assert_called_once_with("Database update failed")
+
+
 @pytest.mark.usefixtures("attach_storage")
 def test_theme_reconciliation(
     patch: WordpressPatch,

tests/unit/wordpress_mock.py

@@ -359,6 +359,7 @@ def __init__(
         self._wordpress_database_mock = wordpress_database_mock
         self.installed_plugins = set(WordpressCharm._WORDPRESS_DEFAULT_PLUGINS)
         self.installed_themes = set(WordpressCharm._WORDPRESS_DEFAULT_THEMES)
+        self._fail_wp_update_database = False
 
     def exec(
         self, cmd, user=None, group=None, working_dir=None, combine_stderr=None, timeout=None
@@ -645,6 +646,13 @@ def _mock_chown_uploads(self, _cmd):
         """Simulate ``chown`` command execution in the container."""
         return ExecProcessMock(return_code=0, stdout="", stderr="")
 
+    @_exec_handler.register(lambda cmd: cmd[:3] == ["wp", "core", "update-db"])
+    def _mock_wp_update_database(self, _cmd):
+        """Simulate ``wp core update-db`` command execution in the container."""
+        if self._fail_wp_update_database:
+            return ExecProcessMock(return_code=1, stdout="", stderr="Database update failed")
+        return ExecProcessMock(return_code=0, stdout="ok", stderr="")
+
     def __getattr__(self, item):
         """Passthrough anything else to :class:`ops.charm.model.Container`.