admin: spears: Remove unused entries when updating from config

src/lkadmin/spears.py

@@ -58,6 +58,8 @@ def _add_migration_task(repo_name: str, source_suites: T.List[str], target_suite
                 raise ValueError('The priority value "{}" is unknown!'.format(prio_name))
             stask.delays[prio_name] = days
 
+        return stask.name
+
 
 @spears.command()
 def configure_all():
@@ -133,13 +135,26 @@ def remove_hint(source_suite, target_suite, hint):
 
 @spears.command()
 @click.argument('config_fname', nargs=1)
-def add_from_config(config_fname):
+def update_from_config(config_fname):
     """Add/update migration tasks from a TOML config file."""
+    from laniakea.db import SpearsMigrationTask
+
     try:
         with open(config_fname, 'r', encoding='utf-8') as f:
             conf = tomlkit.load(f)
     except Exception as e:
         print_error_exit('Unable to load data from configuration file: {}'.format(str(e)))
 
-    for task_d in conf.get('MigrationTasks', []):
-        _add_migration_task(**task_d)
+    with session_scope() as session:
+        entries = session.query(SpearsMigrationTask).all()
+        known_tasks = {}
+        for e in entries:
+            known_tasks[e.name] = e
+
+        for task_d in conf.get('MigrationTasks', []):
+            task_name = _add_migration_task(**task_d)
+            known_tasks.pop(task_name)
+
+        # delete the remaining, orphaned entries
+        for task in known_tasks.values():
+            session.delete(task)