Prevent generation of empty revision files by alembic autogenerate (#…

…39634)

* Prevent generation of empty revision files by alembic autogenerate

When the alembic autogenerate command is run, we should prevent it
from generating an mpty migration file with no upgrade operation.
We print on the command line that no changes were detected.

* fixup! Prevent generation of empty revision files by alembic autogenerate

airflow/migrations/env.py

@@ -94,6 +94,14 @@ def run_migrations_online():
     and associate a connection with the context.
 
     """
+
+    def process_revision_directives(context, revision, directives):
+        if getattr(config.cmd_opts, "autogenerate", False):
+            script = directives[0]
+            if script.upgrade_ops and script.upgrade_ops.is_empty():
+                directives[:] = []
+                print("No change detected in ORM schema, skipping revision.")
+
     with contextlib.ExitStack() as stack:
         connection = config.attributes.get("connection", None)
 
@@ -108,6 +116,7 @@ def run_migrations_online():
             compare_server_default=compare_server_default,
             include_object=include_object,
             render_as_batch=True,
+            process_revision_directives=process_revision_directives,
         )
 
         with context.begin_transaction():

docs/apache-airflow/img/airflow_erd.sha256

@@ -1 +1 @@
-6ae5e112d66c30d36fbc27a608355ffd66853e34d7538223f69a71e2eba54b59
+62c46e83c8c2a7051fa3d7388e06535bcd01fae4cb1d01b1096cc069a82a89f8