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

Question

With my Procfile like this:

web: gunicorn app:app 
    --bind "$HOST:$PORT" 
    --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.

Asked By: kontur

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Source

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

Answered By: kontur

Answer 2

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.

Specify --log-level to debug(default info).
Specify --capture-output flag (default false).

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

Answered By: Satys

Answer 3

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.

Answered By: suvtfopw

Answer 4

I use Python3 along with Flask.

I use print('log info') directly instead of print('log info', flush=True).

I only set capture_output to True and set a errorlog file and it works.

Note that:

capture_output

--capture-output
False
Redirect stdout/stderr to specified file in errorlog

I think it’s that you need to specifiy a errorlog file to get the standard output.

Here’s my config file gunicorn.config.py setting

accesslog = 'gunicorn.log'
errorlog = 'gunicorn.error.log'
capture_output = True

Then run with gunicorn app_py:myapp -c gunicorn.config.py

The equivaluent command line would be

gunicorn app_py:myapp --error-logfile gunicorn.error.log --access-logfile gunicorn.log --capture-output

Answered By: Rick

Answer 5

Personally, I use a trick to print logs. I use file = sys.stderr as a parameter of the print statement. Following is the way out:

import sys
print("WHATEVER YOU WANT", file = sys.stderr)

Done!

Answered By: hafiz031

Answer 6

This is working for me (I’m using a service called si-ct)

gunicorn --workers 3 --bind unix:si-ct.sock -m 007 wsgi:app --log-level debug --error-logfile - --access-logfile - --capture-output --reload

With that, the print output shows in my service logs, which I read using

sudo journalctl -u si-ct -f

Answered By: Rami Alloush

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

Question:

Answers:

capture_output