fix(router): resolve routing group names to member deployment ids

Signed-off-by: pjdurden <prajjwalchittori1@gmail.com>

litellm/router.py

@@ -1167,6 +1167,18 @@ class Router:
             or self.get_routing_group(model) is not None
         )
 
+    def _resolve_to_deployment_model_names(self, model: str) -> tuple[str, ...]:
+        """
+        The deployment `model_name`s behind a requested name: a
+        `model_group_alias` resolves to its target and a callable routing group
+        to its members, so lookups keyed by model group name reach the same
+        deployments the router would route the request to. Names that are
+        neither resolve to themselves.
+        """
+        resolved: Final = self._get_model_from_alias(model=model) or model
+        group: Final = self.get_routing_group(resolved)
+        return tuple(group.models) if group is not None else (resolved,)
+
     def routing_group_has_alternatives(self, model_group: str | None) -> bool:
         """
         True when `model_group` names a callable routing group whose member
@@ -9764,6 +9776,11 @@ class Router:
 
         Returns list of model id's.
 
+        `model_name` may be any name the router serves: a deployment
+        `model_name`, a `model_group_alias`, or a callable routing group, which
+        resolve to the deployments they route to (see
+        `_resolve_to_deployment_model_names`).
+
         Optimized with O(1) or O(k) index lookup when model_name provided,
         instead of O(n) linear scan.
         """
@@ -9771,9 +9788,8 @@ class Router:
 
         if model_name is not None:
             # O(1) lookup in model_name index, then O(k) iteration where k = deployments for this model_name
-            if model_name in self.model_name_to_deployment_indices:
-                indices: Final = self.model_name_to_deployment_indices[model_name]
-                for idx in indices:
+            for deployment_model_name in self._resolve_to_deployment_model_names(model=model_name):
+                for idx in self.model_name_to_deployment_indices.get(deployment_model_name) or ():
                     model = self.model_list[idx]
                     if "model_info" in model and "id" in model["model_info"]:
                         if exclude_team_models and model["model_info"].get("team_id"):

tests/test_litellm/router_strategy/test_router_routing_groups.py

@@ -15,7 +15,7 @@ sys.path.insert(0, os.path.abspath("../.."))
 
 import litellm
 from litellm import Router
-from litellm.types.router import RoutingGroup, RoutingStrategy
+from litellm.types.router import RouterRateLimitError, RoutingGroup, RoutingStrategy
 
 
 def _model_list():
@@ -1068,3 +1068,47 @@ async def test_group_call_429_cools_down_member_across_retries():
     )
     cooldown_ids = await _call_and_get_cooldowns(router, "quality")
     assert "deploy-3" in cooldown_ids
+
+
+def test_get_model_ids_resolves_group_and_alias_to_member_deployments():
+    router = Router(
+        model_list=_model_list(),
+        model_group_alias={"quality-alias": "quality"},
+        routing_groups=_quality_group("simple-shuffle"),
+    )
+    assert sorted(router.get_model_ids(model_name="quality")) == ["deploy-1", "deploy-2", "deploy-3"]
+    assert sorted(router.get_model_ids(model_name="quality-alias")) == ["deploy-1", "deploy-2", "deploy-3"]
+    assert sorted(router.get_model_ids(model_name="filtered-model")) == ["deploy-1", "deploy-2"]
+    assert router.get_model_ids(model_name="not-a-model") == []
+
+
+@pytest.mark.asyncio
+async def test_group_call_reports_member_cooldown_time_when_every_member_is_cooling_down():
+    """
+    Regression: the group name has to resolve to its members' deployment ids, else the
+    429 raised for a fully cooled-down group reports the router's default cooldown
+    instead of the members' own, and the proxy sends that as `retry-after`.
+    """
+    deployment_cooldown_time = 120
+    router = Router(
+        model_list=[
+            {**deployment, "model_info": {**deployment["model_info"], "cooldown_time": deployment_cooldown_time}}
+            for deployment in _model_list()
+        ],
+        routing_groups=_quality_group("simple-shuffle"),
+        num_retries=0,
+    )
+    assert router.cooldown_cache.default_cooldown_time != deployment_cooldown_time
+
+    for deployment_id in ("deploy-1", "deploy-2", "deploy-3"):
+        router.cooldown_cache.add_deployment_to_cooldown(
+            model_id=deployment_id,
+            original_exception=litellm.RateLimitError(message="rate limited", llm_provider="openai", model="gpt-4o"),
+            exception_status=429,
+            cooldown_time=deployment_cooldown_time,
+        )
+
+    with pytest.raises(RouterRateLimitError) as exc_info:
+        await router.async_get_available_deployment(model="quality", request_kwargs={})
+
+    assert exc_info.value.cooldown_time == deployment_cooldown_time