Flask app logger not working when running within gunicorn

Question

I\'m trying to save application log messages from a very simple flask app in a log file. While this works flawlessly when I\'m running the app with the embedded Flask server, it

Answer 1

@Auguiwan's answer does explain the origin question, but not talked about how to solve it.@indrajeet 's answer is quite comprehensive and provides a kind of solution. However, they don't solve my related problem.

My answer mainly tries to help people who get here by searched similar keywords "flask gunicorn log" like me. I find this link is very helpful among related search result https://medium.com/@yoanis_gil/logging-with-docker-part-1-1-965cb5e17165

The part Gunicorn configuration

exec gunicorn ${WSGI_MODULE}:${WSGI_APP} \
  --name $NAME \
  --workers $NUM_WORKERS \
  --user=$USER --group=$GROUP \
  --bind=unix:$SOCKFILE \
  --log-level=info \
  --log-file=/dev/stdout

really helps me out. The core configuration is --log-level and --log-file part.
If you are using supervisored with gunicorn.conf like me, just change related gunicorn.conf file.