fix: disable MySQL backend in forum on upgrade

In Sumac, it was decided that we would not automatically migrating data
from mongodb to mysql. Instead, we encourage users to do so manually, in
the tutor-forum README.

changelog.d/20241119_091908_regis_disable_forum_mysql_on_upgrade.md

@@ -0,0 +1 @@
+- [Feature] With the new forum v2 application, users have a choice to use MongoDB or MySQL as a storage backend, course per course. New users will automatically start using MySQL, while existing users will be responsible for migrating their data themselves (before the Teak release). Upgrade instructions are available here: https://github.com/overhangio/tutor-forum/#installation. (by @regisb)

tutor/commands/upgrade/common.py

@@ -46,6 +46,22 @@ def upgrade_from_nutmeg(context: click.Context, config: Config) -> None:
     )
 
 
+def upgrade_from_redwood(context: click.Context, config: Config) -> None:
+    # Prevent switching to the MySQL storage backend in forum v2
+    if plugins.is_loaded("forum"):
+        fmt.echo_alert(
+            "Your platform is going to be configured to store forum data in MongoDB. "
+            "You are STRONGLY ENCOURAGED to migrate your forum data to MySQL as soon as possible. "
+            "To do so, refer to the tutor-forum plugin documentation: https://github.com/overhangio/tutor-forum/#installation"
+        )
+        context.obj.job_runner(config).run_task(
+            "lms",
+            """
+(./manage.py lms waffle_flag --list | grep forum_v2.enable_mysql_backend) || ./manage.py lms waffle_flag --create --deactivate forum_v2.enable_mysql_backend
+""",
+        )
+
+
 def get_mongo_upgrade_parameters(
     docker_version: str, compatibility_version: str
 ) -> tuple[int, dict[str, int | str]]:

tutor/commands/upgrade/compose.py

@@ -52,6 +52,7 @@ def upgrade_from(context: click.Context, from_release: str) -> None:
         running_release = "redwood"
 
     if running_release == "redwood":
+        common_upgrade.upgrade_from_redwood(context, config)
         running_release = "sumac"
 
 

tutor/commands/upgrade/k8s.py

@@ -50,6 +50,7 @@ def upgrade_from(context: click.Context, from_release: str) -> None:
         running_release = "redwood"
 
     if running_release == "redwood":
+        common_upgrade.upgrade_from_redwood(context, config)
         running_release = "sumac"