Is there a way to log python print statements in gunicorn?

Question

With my Procfile like this:

web: gunicorn app:app \
    --bind "$HOST:$PORT" \
    --debug --error-logfile "-" \
    --enable-stdio-inheritance \
    --reload \
    --log-level "debug" 

is it in any way possible to get python print statements to be logged to stdout / bash? I am using the bottle framework here as well, if that affects anything.

Answer 1

It turns out the print statements were actually getting through, but with delay.

The gunicorn docs for --enable-stdio-inheritance note to set the PYTHONUNBUFFERED, which I thought I had, but it seems with wrong syntax.

I solved it using a .env file with my foreman setup to set the variable like this:

PYTHONUNBUFFERED=TRUE

Answer 2

In python 3, adding flush=True in each print statement works for my flask/gunicorn app.

E.g.

gunicorn --bind 0.0.0.0:8080 server --log-level debug

No particular flags are required.

See if this helps.

Answer 3

Please try below command:

gunicorn --workers 3 --bind 127.0.0.1:5000 --error-logfile /var/log/gunicorn/error.log --access-logfile /var/log/gunicorn/access.log --capture-output --log-level debug

It did work for me.

Please specify log-level to debug(default info)http://docs.gunicorn.org/en/stable/settings.html#loglevel,

Also, specify capture-output flag (default false)http://docs.gunicorn.org/en/stable/settings.html#capture-output.

You should be able to watch logs in error log file.