how to run gunicorn on docker

I just went through this problem this week and stumbled on your question along the way. Fair to say you either resolved this or changed approaches by now, but for future's sake:

The command in my Dockerfile is:

CMD ["gunicorn"  , "-b", "0.0.0.0:8000", "app:app"]

Where the first "app" is the module and the second "app" is the name of the WSGI callable, in your case, it should be _flask from your code although you've some other stuff going on that makes me less certain.

Gunicorn takes the place of all the run statements in your code, if Flask's development web server and Gunicorn try to take the same port it can conflict and crash Gunicorn.

Note that when run by Gunicorn, __name__ is not "main". In my example it is equal to "app".

At my admittedly junior level of both Python, Docker, and Gunicorn the fastest way to debug is to comment out the "CMD" in the Dockerfile, get the container up and running:

docker run -it -d -p 8080:8080 my_image_name

Hop onto the running container:

 docker exec -it container_name /bin/bash

And start Gunicorn from the command line until you've got it working, then test with curl - I keep a basic route in my app.py file that just prints out "Hi" and has no dependencies for validating the server is up before worrying about the port binding to the host machine.

After struggling with this issue over the last 3 days, I found that all you need to do is to bind to the non-routable meta-address 0.0.0.0 rather than the loopback IP 127.0.0.1:

CMD ["gunicorn" , "--bind", "0.0.0.0:8000", "app:app"]

And don't forget to expose the port, one option to do that is to use EXPOSEin your Dockerfile:

EXPOSE 8000

Now:

docker build -t test .

Finally you can run:

docker run -d -p 8000:8000 test

This is my last part of my Dockerfile with Django App

EXPOSE 8002COPY entrypoint.sh /code/WORKDIR /codeENTRYPOINT ["sh", "entrypoint.sh"]

then in entrypoint.sh

#!/bin/bash# Prepare log files and start outputting logs to stdoutmkdir -p /code/logstouch /code/logs/gunicorn.logtouch /code/logs/gunicorn-access.logtail -n 0 -f /code/logs/gunicorn*.log &export DJANGO_SETTINGS_MODULE=django_docker_azure.settingsexec gunicorn django_docker_azure.wsgi:application \    --name django_docker_azure \    --bind 0.0.0.0:8002 \    --workers 5 \    --log-level=info \    --log-file=/code/logs/gunicorn.log \    --access-logfile=/code/logs/gunicorn-access.log \"$@"

Hope this could be useful