[4.1.3] Local uncaught exceptions are not propagated inside JSON-RPC handlers

[MasterGroosha]

Hello. I have a logs.py file with the following code:

import sys
import logging


def setup_log():
    logging.basicConfig(level=logging.INFO)
    _logger = logging.getLogger("myapp")
    fh = logging.FileHandler("log.txt")
    fh.setFormatter(logging.Formatter("%(asctime)s - %(levelname)s - %(message)s"))
    _logger.addHandler(fh)
    sys.excepthook = foo


def foo(exctype, value, tb):
    logger = logging.getLogger("myapp")
    logger.error("Unhandled exception", exc_info=(exctype, value, tb))

And this code does work fine. When in my main file I write something like this:

if __name__ == "__main__":
   raise ValueError("text")

I see this exception in "log.txt" file

However, when I do the same in JSON-RPC handlers:

@method
async def MyRpcMethod(token: str):
   raise ValueError("text")

I get nothing on my server-side. What could be the problem? Is it possible somehow to use such "uncaught exceptions handler" with json-rpc?

[bcb]

I believe sys.excepthook is only called on unhandled exceptions, and jsonrpcserver does handle exceptions, so this could be your problem.

[MasterGroosha]

@bcb thank you for the quick answer! I'm not too familiar with your library, is there any way to keep some exceptions locally rather than return them to the caller?

[bcb]

There are two loggers:

jsonrpcserver.dispatcher.request
jsonrpcserver.dispatcher.response

All you need to do is add handlers to them.

Here's a full example (using StreamHandler):

import logging

from flask import Flask, request, Response
from jsonrpcserver import method, dispatch


app = Flask(__name__)

# Request handler
request_logger = logging.getLogger("jsonrpcserver.dispatcher.request")
request_handler = logging.StreamHandler()
request_logger.addHandler(request_handler)
request_logger.setLevel(logging.INFO)

# Response handler
response_logger = logging.getLogger("jsonrpcserver.dispatcher.response")
response_handler = logging.StreamHandler()
response_logger.addHandler(response_handler)
response_logger.setLevel(logging.INFO)


@method
def ping():
    return "pong"


@app.route("/", methods=["POST"])
def index():
    response = dispatch(request.get_data().decode())
    return Response(str(response), response.http_status, mimetype="application/json")


if __name__ == "__main__":
    app.run()

[MasterGroosha]

@bcb thanks a lot! This is really helpful!