Debugging a Flask app running in Gunicorn

Question

I've been working on a new dev platform using nginx/gunicorn and Flask for my application.

Ops-wise, everything works fine - the issue I'm having is with debugging the Flask layer. When there's an error in my code, I just get a straight 500 error returned to the browser and nothing shows up on the console or in my logs.

I've tried many different configs/options.. I guess I must be missing something obvious.

My gunicorn.conf:

import os

bind = '127.0.0.1:8002'
workers = 3
backlog = 2048
worker_class = "sync"
debug = True
proc_name = 'gunicorn.proc'
pidfile = '/tmp/gunicorn.pid'
logfile = '/var/log/gunicorn/debug.log'
loglevel = 'debug'

An example of some Flask code that borks- testserver.py:

from flask import Flask
from flask import render_template_string
from werkzeug.contrib.fixers import ProxyFix

app = Flask(__name__)

@app.route('/')
def index():
    n = 1/0
    return "DIV/0 worked!"

And finally, the command to run the flask app in gunicorn:

gunicorn -c gunicorn.conf.py testserver:app

Thanks y'all