fix(router): sync model name changes across replicas

litellm/router.py

@@ -6768,7 +6768,12 @@ def upsert_deployment(self, deployment: Deployment) -> Optional[Deployment]:
             )
             if _deployment_on_router is not None:
                 # deployment with this model_id exists on the router
-                if deployment.litellm_params == _deployment_on_router.litellm_params:
+                if (
+                    deployment.litellm_params
+                    == _deployment_on_router.litellm_params
+                    and deployment.model_name
+                    == _deployment_on_router.model_name
+                ):
                     # No need to update
                     return None
 

tests/litellm/test_router_upsert_deployment.py

@@ -0,0 +1,138 @@
+"""
+Tests for router.upsert_deployment() model name change detection.
+
+Regression tests for https://github.com/BerriAI/litellm/issues/22190
+"""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.abspath("../.."))
+
+import litellm
+from litellm.types.router import Deployment, LiteLLM_Params
+
+
+def test_upsert_deployment_detects_model_name_change():
+    """
+    Test that upsert_deployment updates a deployment when model_name changes
+    but litellm_params stay the same.
+
+    Regression test for https://github.com/BerriAI/litellm/issues/22190
+    """
+    router = litellm.Router(
+        model_list=[
+            {
+                "model_name": "original-name",
+                "litellm_params": {
+                    "model": "openai/fake-model",
+                    "api_key": "fake-key",
+                    "api_base": "https://example.com",
+                },
+            },
+        ],
+    )
+
+    # Get the deployment to find its model_id
+    deployment = router.get_deployment_by_model_group_name(
+        model_group_name="original-name"
+    )
+    model_id = deployment.model_info.id
+
+    # Upsert with same litellm_params but different model_name
+    result = router.upsert_deployment(
+        deployment=Deployment(
+            model_name="updated-name",
+            litellm_params=deployment.litellm_params,
+            model_info={"id": model_id},
+        )
+    )
+
+    # Should return the deployment (not None) since the name changed
+    assert result is not None
+
+    # Router should still have exactly 1 deployment
+    assert len(router.model_list) == 1
+
+    # The deployment should have the updated name
+    updated = router.get_deployment(model_id=model_id)
+    assert updated is not None
+    assert updated.model_name == "updated-name"
+
+
+def test_upsert_deployment_skips_when_nothing_changed():
+    """
+    Test that upsert_deployment returns None when neither model_name
+    nor litellm_params have changed.
+    """
+    router = litellm.Router(
+        model_list=[
+            {
+                "model_name": "my-model",
+                "litellm_params": {
+                    "model": "openai/fake-model",
+                    "api_key": "fake-key",
+                    "api_base": "https://example.com",
+                },
+            },
+        ],
+    )
+
+    deployment = router.get_deployment_by_model_group_name(
+        model_group_name="my-model"
+    )
+    model_id = deployment.model_info.id
+
+    # Upsert with identical name and params
+    result = router.upsert_deployment(
+        deployment=Deployment(
+            model_name="my-model",
+            litellm_params=deployment.litellm_params,
+            model_info={"id": model_id},
+        )
+    )
+
+    # Should return None since nothing changed
+    assert result is None
+    assert len(router.model_list) == 1
+
+
+def test_upsert_deployment_detects_litellm_params_change():
+    """
+    Test that upsert_deployment updates a deployment when litellm_params
+    change but model_name stays the same.
+    """
+    router = litellm.Router(
+        model_list=[
+            {
+                "model_name": "my-model",
+                "litellm_params": {
+                    "model": "openai/fake-model",
+                    "api_key": "old-key",
+                    "api_base": "https://example.com",
+                },
+            },
+        ],
+    )
+
+    deployment = router.get_deployment_by_model_group_name(
+        model_group_name="my-model"
+    )
+    model_id = deployment.model_info.id
+
+    # Upsert with same name but different api_key
+    result = router.upsert_deployment(
+        deployment=Deployment(
+            model_name="my-model",
+            litellm_params=LiteLLM_Params(
+                model="openai/fake-model",
+                api_key="new-key",
+                api_base="https://example.com",
+            ),
+            model_info={"id": model_id},
+        )
+    )
+
+    # Should return the deployment since params changed
+    assert result is not None
+    assert len(router.model_list) == 1