Gunicorn: For Flask applications, can you specify a custom request handler?

[gregeinfrank]

I'm looking to do something like this: http://blog.sendhub.com/post/48832423565/hacking-flask-a-success-story which is using a subclass of werkzeug's BaseRequestHandler. You can specify a request_handler in flask's web server directly like so:

app.run(host='0.0.0.0', port=port, request_handler=MyFancyRequestHandler)

But is there a way to specify a request_handler if I'm running my Flask app through gunicorn?

Thanks!

[tilgovi]

Nope. There is no way to do that. Gunicorn is the request handler :-D. You can write your own worker class. What are you trying to accomplish?

[gregeinfrank]

I should have been more specific about what I'm trying to do in my question.

I have a user_id stored on Flask's g object, and for all authenticated requests I'd like to add g.user_id to the request log (which is specified by gunicorn's config)

[berkerpeksag]

You can subclass the gunicorn.glogging.Logger class and override the access method. Then set your new custom logging class to logger_class: http://docs.gunicorn.org/en/19.1.1/settings.html#logger-class

[gregeinfrank]

@berkerpeksag Thanks, can you give an example of how to pass in a custom logger class? I'm trying but it seems like the path isn't accessible

[berkerpeksag]

If you have the following structure:

- app.py  # your flask app
- custom_logger.py  # your glogging subclass YourLoggerClass

you can pass it to Gunicorn like

$ gunicorn app:app --logger-class custom_logger.YourLoggerClass

You can also take a look my implementation at https://github.com/berkerpeksag/django/blob/21978-gunicorn/django/core/servers/gserver.py

[gregeinfrank]

Hmmm still can't get it to work

Error: class uri 'custom_logger.CustomLogger' invalid or not found:

[Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/gunicorn/util.py", line 139, in load_class
mod = import_module('.'.join(components))
File "/usr/lib/python2.7/importlib/init.py", line 37, in import_module
import(name)
ImportError: No module named custom_logger
]

[berkerpeksag]

Oh, it may be a path issue. Try with PYTHONPATH:

$ PYTHONPATH=. gunicorn app:app -b 127.0.0.1:7777 --access-logfile - --error-logfile - --logger-class custom_logger.MyLogger
[2014-11-15 08:03:57 +0000] [23929] [INFO] Starting gunicorn 19.1.1
[2014-11-15 08:03:57 +0000] [23929] [INFO] Listening at: http://127.0.0.1:7777 (23929)
[2014-11-15 08:03:57 +0000] [23929] [INFO] Using worker: sync
[2014-11-15 08:03:57 +0000] [23934] [INFO] Booting worker with pid: 23934
127.0.0.1 - - [15/Nov/2014:08:04:08 +0200] "GET / HTTP/1.1" 200 111 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.104 Safari/537.36"
127.0.0.1 - - [15/Nov/2014:08:04:08 +0200] "GET /static/style.css HTTP/1.1" 304 - "http://127.0.0.1:7777/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.104 Safari/537.36"

[gregeinfrank]

grrr this is so frustrating. Now I get this error:

PYTHONPATH=. gunicorn app:app --logger-class custom_logger.CustomLogger -c /code/gunicorn.py

Traceback (most recent call last):
  File "/usr/local/bin/gunicorn", line 7, in <module>
    from gunicorn.app.wsgiapp import run
ImportError: No module named app.wsgiapp

[tilgovi]

@gregeinfrank that looks unrelated to this issue. It looks like you've got gunicorn installed globally. Are you also using a virtual environment, or no? I'm just wondering if it could be a gunicorn version mismatch.

[berkerpeksag]

Since you've installed Gunicorn globally, you probably need to append the current directory to PYTHONPATH. Please try something like PYTHONPATH=.:$PYTHONPATH.

[gregeinfrank]

That didn't work either because I don't actually have PYTHONPATH set it looks like. I'm running inside of a docker container. Here's all the relevant info:

root@d1e2de0046d0:/code# which gunicorn
/usr/local/bin/gunicorn
root@d1e2de0046d0:/code# which python
/usr/bin/python
root@d1e2de0046d0:/code# echo $PYTHONPATH

root@d1e2de0046d0:/code#

[benoitc]

@gregeinfrank not sur eit's possible but can't you install your logger as a python application using pip? Doing it would put it automatically in your PYTHONPATH.

If not you can set an environment variable in your Dockerfile imo.

[berkerpeksag]

I think we can close this now, it's not directly related to Gunicorn.

[anhdv-teko]

Since you've installed Gunicorn globally, you probably need to append the current directory to PYTHONPATH. Please try something like PYTHONPATH=.:$PYTHONPATH.

This worked for me!