Add a dedicated manual maintenance mode flag

Currently, manually enabling database maintenance mode is awkward, as by
default it will just get switch off again by the regular automatic
check. So you have to remember to stop that first, which is awkward,
then restart it, for more awkwardness

Instead, this change adds an explicit flag check for
`manual-db-maintenance` - if that is set, we skip the automated check
altogether.

This will be added to the jobrunner justfile in backend-server as
a documented command in a separate PR.

jobrunner/service.py

@@ -93,6 +93,14 @@ def maintenance_mode():
     """Check if the db is currently in maintenance mode, and set flags as appropriate."""
     # This did not seem big enough to warrant splitting into a separate module.
     log.info("checking if db undergoing maintenance...")
+
+    # manually setting this flag bypasses the automaticaly check
+    manual_db_mode = get_flag_value("manual-db-maintenance")
+    if manual_db_mode:
+        log.info(f"manually set db mode: db-maintenance")
+        return "db-maintenance"
+
+    # detect db mode from TPP.
     current = get_flag_value("mode")
     ps = docker(
         [

tests/test_service.py

@@ -93,6 +93,11 @@ def test_maintenance_mode_error(mock_subprocess_run, db, db_config):
         service.maintenance_mode()
 
 
+def test_maintenance_mode_manual(db, db_config):
+    queries.set_flag("manual-db-maintenance", "on")
+    assert service.maintenance_mode() == "db-maintenance"
+
+
 @pytest.fixture
 def db_config(monkeypatch):
     monkeypatch.setitem(config.DATABASE_URLS, "default", "mssql://localhost")