Minimal concept to research django/daphne#557 (comment)

Create the docker image

docker build -t daphne -f ./Dockerfile .

Run the docker image (to verify the exception: ValueError: Unknown endpoint type: 'fd')

docker run daphne

Uncomment the "COPY server.py" line in DockerFile

Create the docker image

docker build -t daphne -f ./Dockerfile .

Run the docker image (to verify the exception is gone)

docker run daphne