[Fix] Fix Pass through routes to work with server root path (#19383)

* test_build_full_path_with_root_default

* fix pt feat

litellm/proxy/pass_through_endpoints/pass_through_endpoints.py

@@ -51,6 +51,7 @@ from litellm.proxy._types import (
 from litellm.proxy.auth.user_api_key_auth import user_api_key_auth
 from litellm.proxy.common_request_processing import ProxyBaseLLMRequestProcessing
 from litellm.proxy.common_utils.http_parsing_utils import _read_request_body
+from litellm.proxy.utils import get_server_root_path
 from litellm.secret_managers.main import get_secret_str
 from litellm.types.llms.custom_http import httpxSpecialProvider
 from litellm.types.passthrough_endpoints.pass_through_endpoints import (
@@ -1973,10 +1974,26 @@ class InitPassThroughEndpointHelpers:
         _registered_pass_through_routes.clear()
 
     @staticmethod
-    def get_registered_pass_through_endpoints_keys() -> List[str]:
+    def get_all_registered_pass_through_routes() -> List[str]:
         """Get all registered pass-through endpoints from the registry"""
         return list(_registered_pass_through_routes.keys())
 
+    @staticmethod
+    def _build_full_path_with_root(path: str) -> str:
+        """
+        Build full path by prepending server root path if needed.
+
+        Args:
+            path: The relative path to build
+
+        Returns:
+            Full path with server root prepended (if root is not "/")
+        """
+        root_path = get_server_root_path()
+        if root_path == "/":
+            return path
+        return f"{root_path}{path}"
+
     @staticmethod
     def is_registered_pass_through_route(route: str) -> bool:
         """
@@ -2003,7 +2020,9 @@ class InitPassThroughEndpointHelpers:
             parts = key.split(":", 2)  # Split into [endpoint_id, type, path]
             if len(parts) == 3:
                 route_type = parts[1]
-                registered_path = parts[2]
+                registered_path = InitPassThroughEndpointHelpers._build_full_path_with_root(
+                    parts[2]
+                )
                 if route_type == "exact" and route == registered_path:
                     return True
                 elif route_type == "subpath":
@@ -2021,7 +2040,9 @@ class InitPassThroughEndpointHelpers:
             parts = key.split(":", 2)  # Split into [endpoint_id, type, path]
             if len(parts) == 3:
                 route_type = parts[1]
-                registered_path = parts[2]
+                registered_path = InitPassThroughEndpointHelpers._build_full_path_with_root(
+                    parts[2]
+                )
 
                 if route_type == "exact" and route == registered_path:
                     return _registered_pass_through_routes[key]
@@ -2085,7 +2106,7 @@ async def initialize_pass_through_endpoints(
     # mark the ones that are visited in the list
     # remove the ones that are not visited from the list
     registered_pass_through_endpoints = (
-        InitPassThroughEndpointHelpers.get_registered_pass_through_endpoints_keys()
+        InitPassThroughEndpointHelpers.get_all_registered_pass_through_routes()
     )
 
     visited_endpoints = set()

tests/test_litellm/proxy/pass_through_endpoints/test_pass_through_endpoints.py

@@ -1897,8 +1897,8 @@ async def test_add_litellm_data_to_request_adds_headers_to_metadata():
     The fix ensures headers are available in data["metadata"]["headers"] so
     guardrails can validate User-Agent, API keys, and other header-based checks.
     """
-    from litellm.proxy.litellm_pre_call_utils import add_litellm_data_to_request
     from litellm.proxy._types import UserAPIKeyAuth
+    from litellm.proxy.litellm_pre_call_utils import add_litellm_data_to_request
 
     # Create mock request with headers including User-Agent
     mock_request = MagicMock(spec=Request)
@@ -1954,3 +1954,150 @@ async def test_add_litellm_data_to_request_adds_headers_to_metadata():
     # Also verify proxy_server_request has headers (original location)
     assert "proxy_server_request" in result
     assert "headers" in result["proxy_server_request"]
+
+
+def test_build_full_path_with_root_default():
+    """
+    Test _build_full_path_with_root with default root path (/)
+    """
+    from litellm.proxy.pass_through_endpoints.pass_through_endpoints import (
+        InitPassThroughEndpointHelpers,
+    )
+
+    with patch("litellm.proxy.pass_through_endpoints.pass_through_endpoints.get_server_root_path") as mock_get_root:
+        # Test with default root path
+        mock_get_root.return_value = "/"
+
+        result = InitPassThroughEndpointHelpers._build_full_path_with_root("/api/v1/endpoint")
+        assert result == "/api/v1/endpoint"
+
+
+def test_build_full_path_with_root_custom():
+    """
+    Test _build_full_path_with_root with custom root path
+    """
+    from litellm.proxy.pass_through_endpoints.pass_through_endpoints import (
+        InitPassThroughEndpointHelpers,
+    )
+
+    with patch("litellm.proxy.pass_through_endpoints.pass_through_endpoints.get_server_root_path") as mock_get_root:
+        # Test with custom root path /proxy
+        mock_get_root.return_value = "/proxy"
+
+        result = InitPassThroughEndpointHelpers._build_full_path_with_root("/api/v1/endpoint")
+        assert result == "/proxy/api/v1/endpoint"
+
+
+def test_build_full_path_with_root_nested():
+    """
+    Test _build_full_path_with_root with nested root path
+    """
+    from litellm.proxy.pass_through_endpoints.pass_through_endpoints import (
+        InitPassThroughEndpointHelpers,
+    )
+
+    with patch("litellm.proxy.pass_through_endpoints.pass_through_endpoints.get_server_root_path") as mock_get_root:
+        # Test with nested root path /api/v2
+        mock_get_root.return_value = "/api/v2"
+
+        result = InitPassThroughEndpointHelpers._build_full_path_with_root("/endpoint")
+        assert result == "/api/v2/endpoint"
+
+
+def test_is_registered_pass_through_route_with_custom_root():
+    """
+    Test is_registered_pass_through_route correctly handles server root path
+
+    When server has a custom root path like /proxy, the registered path
+    should be constructed by prepending the root to match incoming routes.
+    """
+    from litellm.proxy.pass_through_endpoints.pass_through_endpoints import (
+        InitPassThroughEndpointHelpers,
+        _registered_pass_through_routes,
+    )
+
+    # Clear the registry first
+    _registered_pass_through_routes.clear()
+
+    # Register a pass-through route with endpoint format: {endpoint_id}:exact:{path}
+    endpoint_id = "test-endpoint-123"
+    path = "/api/endpoint"
+    route_key = f"{endpoint_id}:exact:{path}"
+    _registered_pass_through_routes[route_key] = {
+        "target": "http://example.com",
+        "headers": {},
+    }
+
+    with patch("litellm.proxy.pass_through_endpoints.pass_through_endpoints.get_server_root_path") as mock_get_root:
+        # Test with custom root path /proxy
+        mock_get_root.return_value = "/proxy"
+
+        # Should match when request route includes the root path
+        assert InitPassThroughEndpointHelpers.is_registered_pass_through_route("/proxy/api/endpoint") is True
+
+        # Should not match when request route doesn't include root path
+        assert InitPassThroughEndpointHelpers.is_registered_pass_through_route("/api/endpoint") is False
+
+        # Test with default root path
+        mock_get_root.return_value = "/"
+
+        # Should match with default root
+        assert InitPassThroughEndpointHelpers.is_registered_pass_through_route("/api/endpoint") is True
+
+        # Should not match with root prepended when root is /
+        assert InitPassThroughEndpointHelpers.is_registered_pass_through_route("/proxy/api/endpoint") is False
+
+    # Clean up
+    _registered_pass_through_routes.clear()
+
+
+def test_get_registered_pass_through_route_with_custom_root():
+    """
+    Test get_registered_pass_through_route correctly handles server root path
+
+    When server has a custom root path, the method should return the correct
+    endpoint configuration by matching the full path including the root.
+    """
+    from litellm.proxy.pass_through_endpoints.pass_through_endpoints import (
+        InitPassThroughEndpointHelpers,
+        _registered_pass_through_routes,
+    )
+
+    # Clear the registry first
+    _registered_pass_through_routes.clear()
+
+    # Register a pass-through route
+    endpoint_id = "test-endpoint-456"
+    path = "/chat/completions"
+    target_config = {
+        "target": "http://api.example.com/v1/chat/completions",
+        "headers": {"Authorization": "Bearer token123"},
+        "forward_headers": True,
+    }
+    route_key = f"{endpoint_id}:exact:{path}"
+    _registered_pass_through_routes[route_key] = target_config
+
+    with patch("litellm.proxy.pass_through_endpoints.pass_through_endpoints.get_server_root_path") as mock_get_root:
+        # Test with custom root path /litellm
+        mock_get_root.return_value = "/litellm"
+
+        # Should return config when request route includes root path
+        result = InitPassThroughEndpointHelpers.get_registered_pass_through_route("/litellm/chat/completions")
+        assert result is not None
+        assert result["target"] == "http://api.example.com/v1/chat/completions"
+        assert result["headers"]["Authorization"] == "Bearer token123"
+
+        # Should return None when route doesn't match
+        result = InitPassThroughEndpointHelpers.get_registered_pass_through_route("/chat/completions")
+        assert result is None
+
+        # Test with default root path
+        mock_get_root.return_value = "/"
+
+        # Should return config with default root
+        result = InitPassThroughEndpointHelpers.get_registered_pass_through_route("/chat/completions")
+        assert result is not None
+        assert result["target"] == "http://api.example.com/v1/chat/completions"
+
+    # Clean up
+    _registered_pass_through_routes.clear()