docs(pass_through.md): add doc on creating custom chat endpoints on proxy

Allows developers to call proxy with anthropic sdk/boto3/etc.

litellm/proxy/pass_through_endpoints/pass_through_endpoints.py

@@ -1,4 +1,6 @@
 import ast
+import asyncio
+import json
 import traceback
 from base64 import b64encode
 
@@ -16,7 +18,8 @@ from fastapi.responses import StreamingResponse
 
 import litellm
 from litellm._logging import verbose_proxy_logger
-from litellm.proxy._types import ProxyException
+from litellm.integrations.custom_logger import CustomLogger
+from litellm.proxy._types import ProxyException, UserAPIKeyAuth
 from litellm.proxy.auth.user_api_key_auth import user_api_key_auth
 
 async_client = httpx.AsyncClient()
@@ -24,7 +27,7 @@ async_client = httpx.AsyncClient()
 
 async def set_env_variables_in_header(custom_headers: dict):
     """
-    checks if nay headers on config.yaml are defined as os.environ/COHERE_API_KEY etc
+    checks if any headers on config.yaml are defined as os.environ/COHERE_API_KEY etc
 
     only runs for headers defined on config.yaml
 
@@ -72,6 +75,171 @@ async def set_env_variables_in_header(custom_headers: dict):
     return headers
 
 
+async def chat_completion_pass_through_endpoint(
+    fastapi_response: Response,
+    request: Request,
+    adapter_id: str,
+    user_api_key_dict: UserAPIKeyAuth,
+):
+    from litellm.proxy.proxy_server import (
+        add_litellm_data_to_request,
+        general_settings,
+        get_custom_headers,
+        llm_router,
+        proxy_config,
+        proxy_logging_obj,
+        user_api_base,
+        user_max_tokens,
+        user_model,
+        user_request_timeout,
+        user_temperature,
+        version,
+    )
+
+    data = {}
+    try:
+        body = await request.body()
+        body_str = body.decode()
+        try:
+            data = ast.literal_eval(body_str)
+        except Exception:
+            data = json.loads(body_str)
+
+        data["adapter_id"] = adapter_id
+
+        verbose_proxy_logger.debug(
+            "Request received by LiteLLM:\n{}".format(json.dumps(data, indent=4)),
+        )
+        data["model"] = (
+            general_settings.get("completion_model", None)  # server default
+            or user_model  # model name passed via cli args
+            or data["model"]  # default passed in http request
+        )
+        if user_model:
+            data["model"] = user_model
+
+        data = await add_litellm_data_to_request(
+            data=data,  # type: ignore
+            request=request,
+            general_settings=general_settings,
+            user_api_key_dict=user_api_key_dict,
+            version=version,
+            proxy_config=proxy_config,
+        )
+
+        # override with user settings, these are params passed via cli
+        if user_temperature:
+            data["temperature"] = user_temperature
+        if user_request_timeout:
+            data["request_timeout"] = user_request_timeout
+        if user_max_tokens:
+            data["max_tokens"] = user_max_tokens
+        if user_api_base:
+            data["api_base"] = user_api_base
+
+        ### MODEL ALIAS MAPPING ###
+        # check if model name in model alias map
+        # get the actual model name
+        if data["model"] in litellm.model_alias_map:
+            data["model"] = litellm.model_alias_map[data["model"]]
+
+        ### CALL HOOKS ### - modify incoming data before calling the model
+        data = await proxy_logging_obj.pre_call_hook(  # type: ignore
+            user_api_key_dict=user_api_key_dict, data=data, call_type="text_completion"
+        )
+
+        ### ROUTE THE REQUESTs ###
+        router_model_names = llm_router.model_names if llm_router is not None else []
+        # skip router if user passed their key
+        if "api_key" in data:
+            llm_response = asyncio.create_task(litellm.aadapter_completion(**data))
+        elif (
+            llm_router is not None and data["model"] in router_model_names
+        ):  # model in router model list
+            llm_response = asyncio.create_task(llm_router.aadapter_completion(**data))
+        elif (
+            llm_router is not None
+            and llm_router.model_group_alias is not None
+            and data["model"] in llm_router.model_group_alias
+        ):  # model set in model_group_alias
+            llm_response = asyncio.create_task(llm_router.aadapter_completion(**data))
+        elif (
+            llm_router is not None and data["model"] in llm_router.deployment_names
+        ):  # model in router deployments, calling a specific deployment on the router
+            llm_response = asyncio.create_task(
+                llm_router.aadapter_completion(**data, specific_deployment=True)
+            )
+        elif (
+            llm_router is not None and data["model"] in llm_router.get_model_ids()
+        ):  # model in router model list
+            llm_response = asyncio.create_task(llm_router.aadapter_completion(**data))
+        elif (
+            llm_router is not None
+            and data["model"] not in router_model_names
+            and llm_router.default_deployment is not None
+        ):  # model in router deployments, calling a specific deployment on the router
+            llm_response = asyncio.create_task(llm_router.aadapter_completion(**data))
+        elif user_model is not None:  # `litellm --model <your-model-name>`
+            llm_response = asyncio.create_task(litellm.aadapter_completion(**data))
+        else:
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail={
+                    "error": "completion: Invalid model name passed in model="
+                    + data.get("model", "")
+                },
+            )
+
+        # Await the llm_response task
+        response = await llm_response
+
+        hidden_params = getattr(response, "_hidden_params", {}) or {}
+        model_id = hidden_params.get("model_id", None) or ""
+        cache_key = hidden_params.get("cache_key", None) or ""
+        api_base = hidden_params.get("api_base", None) or ""
+        response_cost = hidden_params.get("response_cost", None) or ""
+
+        ### ALERTING ###
+        asyncio.create_task(
+            proxy_logging_obj.update_request_status(
+                litellm_call_id=data.get("litellm_call_id", ""), status="success"
+            )
+        )
+
+        verbose_proxy_logger.debug("final response: %s", response)
+
+        fastapi_response.headers.update(
+            get_custom_headers(
+                user_api_key_dict=user_api_key_dict,
+                model_id=model_id,
+                cache_key=cache_key,
+                api_base=api_base,
+                version=version,
+                response_cost=response_cost,
+            )
+        )
+
+        verbose_proxy_logger.info("\nResponse from Litellm:\n{}".format(response))
+        return response
+    except Exception as e:
+        await proxy_logging_obj.post_call_failure_hook(
+            user_api_key_dict=user_api_key_dict, original_exception=e, request_data=data
+        )
+        verbose_proxy_logger.error(
+            "litellm.proxy.proxy_server.completion(): Exception occured - {}\n{}".format(
+                str(e), traceback.format_exc()
+            )
+        )
+        verbose_proxy_logger.debug(traceback.format_exc())
+        error_msg = f"{str(e)}"
+        raise ProxyException(
+            message=getattr(e, "message", error_msg),
+            type=getattr(e, "type", "None"),
+            param=getattr(e, "param", "None"),
+            code=getattr(e, "status_code", 500),
+        )
+
+
 async def pass_through_request(request: Request, target: str, custom_headers: dict):
     try:
 
@@ -106,7 +274,7 @@ async def pass_through_request(request: Request, target: str, custom_headers: di
         )
     except Exception as e:
         verbose_proxy_logger.error(
-            "litellm.proxy.proxy_server.pass through endpoint(): Exception occured - {}".format(
+            "litellm.proxy.proxy_server.pass_through_endpoint(): Exception occured - {}".format(
                 str(e)
             )
         )
@@ -128,9 +296,37 @@ async def pass_through_request(request: Request, target: str, custom_headers: di
             )
 
 
-def create_pass_through_route(endpoint, target, custom_headers=None):
-    async def endpoint_func(request: Request):
-        return await pass_through_request(request, target, custom_headers)
+def create_pass_through_route(endpoint, target: str, custom_headers=None):
+    # check if target is an adapter.py or a url
+    import uuid
+
+    from litellm.proxy.utils import get_instance_fn
+
+    try:
+        if isinstance(target, CustomLogger):
+            adapter = target
+        else:
+            adapter = get_instance_fn(value=target)
+        adapter_id = str(uuid.uuid4())
+        litellm.adapters = [{"id": adapter_id, "adapter": adapter}]
+
+        async def endpoint_func(
+            request: Request,
+            fastapi_response: Response,
+            user_api_key_dict: UserAPIKeyAuth = Depends(user_api_key_auth),
+        ):
+            return await chat_completion_pass_through_endpoint(
+                fastapi_response=fastapi_response,
+                request=request,
+                adapter_id=adapter_id,
+                user_api_key_dict=user_api_key_dict,
+            )
+
+    except Exception:
+        verbose_proxy_logger.warning("Defaulting to target being a url.")
+
+        async def endpoint_func(request: Request):  # type: ignore
+            return await pass_through_request(request, target, custom_headers)
 
     return endpoint_func