[serve] add cors warnings (#40112)

* add cors warnings

* Update src/transformers/commands/serving.py

Co-authored-by: Quentin Gallouédec <[email protected]>

* Update src/transformers/commands/serving.py

Co-authored-by: Arthur <[email protected]>

* Apply suggestions from code review

* make fixup

---------

Co-authored-by: Quentin Gallouédec <[email protected]>
Co-authored-by: Arthur <[email protected]>

Author: 3 people

src/transformers/commands/serving.py

@@ -634,6 +634,13 @@ def run(self):
                 allow_methods=["*"],
                 allow_headers=["*"],
             )
+            logger.warning_once(
+                "CORS allow origin is set to `*`. This is not recommended for production environments."
+            )
+        else:
+            logger.warning_once(
+                "Some apps may require CORS. Consider launching the server with `--enable-cors` if you see errors."
+            )
 
         @app.post("/v1/chat/completions")
         def chat_completion(request: dict):