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

python debugging logging bottle gunicorn

50,468

Solution 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

Solution 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.

Solution 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.

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

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

Solution 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

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50,468

Author by

kontur

Interested in solving problems.

Updated on July 08, 2022

Comments

kontur almost 2 years
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.
FelikZ over 7 years

Even though it is official way to do it - it does not work for unknown reason (python 2.7)
kontur almost 4 years

It doesn't seem convenient to change the app code to work around this.
Rami Alloush over 2 years

No way to auto create it? FileNotFoundError: [Errno 2] No such file or directory: '/var/log/gunicorn/error.log'
Naveen Reddy Marthala over 2 years

is there a way to redirect all stdout and stderr to a separate file than what's specified in --error-log?