The problem with Gunicorn's logging (mentioned in this thread) that I've seen many people have is that it sends normal events to stderr.
This repo shows how you can configure Gunicorn to have sensible logging: normal events should go to stdout and errors to stderr.
Just run ./run.sh to run a Gunicorn server, then you can
curl http://localhost:9000 for a normal response and
curl http://localhost:9000/404 for a 404 response.
First off, this creates a bash function color in run.sh so that we can
clearly see which lines are stdout and which are stderr. This is how the output
looks like after requesting a normal and a 404 response:
The Python logging is configured in gunicorn.py and then referenced when running Gunicorn.