Launching gunicorn instances a docker image, using docker run

Question

In my dockerfile, for a Flask app, I have a set of commands that work as planned. The last line of my dockerfile is currently:

ENTRYPOINT [ "/bin/bash", "-c" ]

I need to launch some gunicorn instances for this image. So, I run the following commands in the terminal, outside the image.

$ docker run -itd --name running_name -p 5000:5000 image_name bash

If I run without bash, I'll just enter exit the container automatically after a few seconds...

$docker container exec -it running_name  /bin/bash -c bash

Now that I'm in, I launch the gunicorn instances, and do docker exit. Because of exec, the instances are still running.

Is there a way to launch the gunicorn instances from docker run, without having to enter into the container?

I've tried ENTRYPOINT [ "gunicorn", "--bind", "0.0.0.0:5000" ] but I still exit automatically

I've also tried substituting the last line for CMD gunicorn --bind 0.0.0.0:5000 and then do docker run -d --name run_name -p 5000:5000 image_name

I still exit automatically.

Edit: To reflect the possible answer below, here's my updated tries and extra information.

The following files are all at the same level of the directory structure.

In the api_docker.py file, I have:

app = Flask(__name__)
api = Api(app)
api.add_resource(<some_code>)

In the gunicorn.conf.py file, I have:

worker_class = "gevent"
workers = 2
timeout = 90
bind = "0.0.0.0:5000"
wsgi_app = "wsgi:app"
errorlog = "logging/error.log"
capture_output = True
loglevel = "debug"
daemon = True
enable_stdio_inheritance = True
preload = True

I've also tried removing the bind and wsgi_app rows, from this file.

In the dockerfile:

<some_code>
CMD ["gunicorn", "--conf", "gunicorn.conf.py", "--bind", "0.0.0.0:5000", "api_docker:app"]

I build successfully, and then I do:

docker run -d --name name_run -p 5000:5000 name_image

Answer 1

You need to give gunicorn a module to actually run, e.g. app:main for an app.py file with a main function, and you should do this all as the CMD, not ENTRYPOINT, or from docker run unless you plan on providing further gunicorn-related arguments when you actually run the image. (run arguments or the CMD are appended to the ENTRYPOINT)

Or, you could use an existing image that already has these details for you - e.g. https://github.com/tiangolo/meinheld-gunicorn-flask-docker

Answer 2

To solve this issue, I did the following:

1. Removed the options daemon , enable_stdio_inheritance, and preload from the conf file.
2. I also increased the timeout and graceful timeout parameters to 120.
3. Gunicorn will look for a conf file, and will use the parameter values defined therein, unless they are overwritten in th CLI. Therefore, I just ran CMD ["gunicorn"].

I think the most important change was that of point 1, namely the daemon to false(which is the default), not sure why though... I would guess that as a daemon process, the docker container would not monitor it correctly and just exit.