Add /vllm/* and /mistral/* passthrough endpoints (adds support for Mistral OCR via passthrough)

* feat(llm_passthrough_endpoints.py): support mistral passthrough

Closes https://github.com/BerriAI/litellm/issues/9051

* feat(llm_passthrough_endpoints.py): initial commit for adding vllm passthrough route

* feat(vllm/common_utils.py): add new vllm model info route

make it possible to use vllm passthrough route via factory function

* fix(llm_passthrough_endpoints.py): add all methods to vllm passthrough route

* fix: fix linting error

* fix: fix linting error

* fix: fix ruff check

* fix(proxy/_types.py): add new passthrough routes

* docs(config_settings.md): add mistral env vars to docs

litellm/llms/vllm/common_utils.py

@@ -0,0 +1,75 @@
+from typing import List, Optional, Union
+
+import httpx
+
+import litellm
+from litellm.llms.base_llm.base_utils import BaseLLMModelInfo
+from litellm.llms.base_llm.chat.transformation import BaseLLMException
+from litellm.secret_managers.main import get_secret_str
+from litellm.types.llms.openai import AllMessageValues
+from litellm.utils import _add_path_to_api_base
+
+
+class VLLMError(BaseLLMException):
+    pass
+
+
+class VLLMModelInfo(BaseLLMModelInfo):
+    def validate_environment(
+        self,
+        headers: dict,
+        model: str,
+        messages: List[AllMessageValues],
+        optional_params: dict,
+        litellm_params: dict,
+        api_key: Optional[str] = None,
+        api_base: Optional[str] = None,
+    ) -> dict:
+        """Google AI Studio sends api key in query params"""
+        return headers
+
+    @staticmethod
+    def get_api_base(api_base: Optional[str] = None) -> Optional[str]:
+        api_base = api_base or get_secret_str("VLLM_API_BASE")
+        if api_base is None:
+            raise ValueError(
+                "VLLM_API_BASE is not set. Please set the environment variable, to use VLLM's pass-through - `{LITELLM_API_BASE}/vllm/{endpoint}`."
+            )
+        return api_base
+
+    @staticmethod
+    def get_api_key(api_key: Optional[str] = None) -> Optional[str]:
+        return None
+
+    @staticmethod
+    def get_base_model(model: str) -> Optional[str]:
+        return model
+
+    def get_models(
+        self, api_key: Optional[str] = None, api_base: Optional[str] = None
+    ) -> List[str]:
+        api_base = VLLMModelInfo.get_api_base(api_base)
+        api_key = VLLMModelInfo.get_api_key(api_key)
+        endpoint = "/v1/models"
+        if api_base is None or api_key is None:
+            raise ValueError(
+                "GEMINI_API_BASE or GEMINI_API_KEY is not set. Please set the environment variable, to query Gemini's `/models` endpoint."
+            )
+
+        url = _add_path_to_api_base(api_base, endpoint)
+        response = litellm.module_level_client.get(
+            url=url,
+        )
+
+        response.raise_for_status()
+
+        models = response.json()["data"]
+
+        return [model["id"] for model in models]
+
+    def get_error_class(
+        self, error_message: str, status_code: int, headers: Union[dict, httpx.Headers]
+    ) -> BaseLLMException:
+        return VLLMError(
+            status_code=status_code, message=error_message, headers=headers
+        )