Add log statements when we 400, to make it clearer what's happening. (#729)

Author: squidarth

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "truss"
-version = "0.7.16"
+version = "0.7.17rc1"
 description = "A seamless bridge from model development to model delivery"
 license = "MIT"
 readme = "README.md"

truss/templates/server/common/truss_server.py

@@ -45,7 +45,9 @@ async def parse_body(request: Request) -> bytes:
     try:
         return await request.body()
     except ClientDisconnect as exc:
-        raise HTTPException(status_code=499, detail="Client disconnected") from exc
+        error_message = "Client disconnected"
+        logging.error(error_message)
+        raise HTTPException(status_code=499, detail=error_message) from exc
 
 
 FORMAT = "%(asctime)s.%(msecs)03d %(name)s %(levelname)s [%(funcName)s():%(lineno)s] %(message)s"
@@ -135,9 +137,9 @@ async def predict(
             try:
                 body = json.loads(body_raw)
             except json.JSONDecodeError as e:
-                raise HTTPException(
-                    status_code=400, detail=f"Invalid JSON payload: {str(e)}"
-                )
+                error_message = f"Invalid JSON payload: {str(e)}"
+                logging.error(error_message)
+                raise HTTPException(status_code=400, detail=error_message)
 
         # calls ModelWrapper.__call__, which runs validate, preprocess, predict, and postprocess
         response: Union[Dict, Generator] = await model(