Docker image for daphne (interface server for Django channels)

See https://github.com/django/daphne/ and https://channels.readthedocs.io/en/stable/.

Building the image

docker-compose build

or just pull it with:

docker-compose pull

Using the image

To use the image, you will most likely want to create your own Dockerfile that looks something like this:

FROM tbeadle/daphne:1.0.3
COPY proj/channel_settings.py /home/daphne/proj/
# This is only needed if daphne is going to be running behind a proxy like nginx.
CMD ["--proxy-headers"]

In this case, proj/channel_settings.py is a file that contains the CHANNEL_LAYERS setting from your project's settings.py. What I like to do, so that my daphne image is as minimal as possible, is create a channel_settings.py in the same directory as settings.py that contains something like this:

CHANNEL_LAYERS = {
    'default': {
        'BACKEND': 'asgi_redis.RedisChannelLayer',
        'ROUTING':
            'proj.routing.channel_routing'
            if 'SECRET_KEY' in os.environ
            else [],
        'CONFIG': {
            'hosts': [(os.environ.get('REDIS_HOST', 'redis'), 6379)],
        },
    },
}

# These will get overridden in settings.py but are necessary for daphne to be
# able to start.  django.setup() requires that they be set.
DEBUG = False
LOGGING = {}
SECRET_KEY = 'this can be anything except an empty string'

Then, at the top of my project's settings.py, I put:

from .channel_settings import *

This way the CHANNEL_LAYERS setting is in one place that can be used by my django project and by my daphne instance.

The important thing is that this file gets copied to /home/daphne/proj/channel_settings.py by way of the Dockerfile.

The CMD contains command-line options to give to daphne besides the default ones, which include:

-b 0.0.0.0 --access-log - [your options go here] proj.asgi:channel_layer

See https://github.com/tbeadle/docker-gunicorn/tree/master/samples/django_channels for an example that uses this image.