We want to deploy our docker-images to heroku, but heroku provides ports on runtime and doesn’t listen to EXPOSE in docker. So there has been a real struggle to let the COMMAND take in $PORT over existing rasa docker images.
The big problem is when heroku reads in the dockerfile it adds \ infront of variables.
We managed to get it working in the end by not using the rasa docker image
and making a script including $PORT to make it possible to decide on PORT on runtime.
If you have better solution please tell me 