Make use of new callback step for external provisioning

Interaction with LSO is now completely reworked. More efficient, more faster, more better, more prettier, and will make us all rich

Depends on lso!51 (merged)

gso/migrations/env.py

 import logging
-import os
 
-import orchestrator
 from alembic import context
 from orchestrator.db.database import BaseModel
 from orchestrator.settings import app_settings
-from sqlalchemy import engine_from_config, pool
+from sqlalchemy import engine_from_config, pool, text
 
 # this is the Alembic Config object, which provides
 # access to the values within the .ini file in use.
@@ -17,17 +15,8 @@ logger = logging.getLogger("alembic.env")
 
 config.set_main_option("sqlalchemy.url", app_settings.DATABASE_URI)
 
-# add your model's MetaData object here
-# for 'autogenerate' support
-# from myapp import mymodel
-# target_metadata = mymodel.Base.metadata
 target_metadata = BaseModel.metadata
 
-# other values from the config, defined by the needs of env.py,
-# can be acquired:
-# my_important_option = config.get_main_option("my_important_option")
-# ... etc.
-
 
 def run_migrations_offline() -> None:
     """Run migrations in 'offline' mode.
@@ -85,8 +74,10 @@ def run_migrations_online() -> None:
     )
     try:
         with context.begin_transaction():
+            connection.execute(text("SELECT pg_advisory_xact_lock(1000);"))
             context.run_migrations()
     finally:
+        connection.execute(text("SELECT pg_advisory_unlock(1000);"))
         connection.close()