Jun 26 MT-2 phase

migrations_tenant/env.py

@@ -0,0 +1,62 @@
+"""
+migrations_tenant/env.py
+------------------------
+Standalone Alembic environment for running the EXISTING tenant migration chain
+(migrations/versions) against an ARBITRARY tenant database.
+
+Unlike migrations/env.py — which is Flask-Migrate-coupled and always targets
+the app's default database via current_app — this reads sqlalchemy.url straight
+from the Alembic config supplied per-tenant by control/tenant_migrate.py, and
+reuses the same version scripts through version_locations. No Flask import, so
+it can run for any tenant DB outside an app context.
+
+The normal `flask db ...` workflow is unaffected; it still uses migrations/env.py.
+"""
+
+from logging.config import fileConfig
+
+from sqlalchemy import create_engine, pool
+from alembic import context
+
+config = context.config
+
+# Only configure logging if an ini file was supplied (the runner builds the
+# Config programmatically, so this is typically skipped).
+if config.config_file_name is not None:
+    try:
+        fileConfig(config.config_file_name)
+    except Exception:
+        pass
+
+# Raw-SQL migrations with INFORMATION_SCHEMA guards — autogenerate is not used,
+# so no target metadata is required here.
+target_metadata = None
+
+
+def run_migrations_offline():
+    context.configure(
+        url=config.get_main_option('sqlalchemy.url'),
+        target_metadata=target_metadata,
+        literal_binds=True,
+        compare_type=False,
+    )
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    url = config.get_main_option('sqlalchemy.url')
+    connectable = create_engine(url, poolclass=pool.NullPool, future=True)
+    try:
+        with connectable.connect() as connection:
+            context.configure(connection=connection, target_metadata=target_metadata)
+            with context.begin_transaction():
+                context.run_migrations()
+    finally:
+        connectable.dispose()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()