Docker Configuration Files and Command Scripts.

Issues, Solutions and Workarounds (OSX)

From Host to Docker

Use EXPOSE and --publish (or -p, -P). Personally, I use default ports within the container and map them to fixed host ports. For example, I use 10022, 20022 for ssh server and 15432, 25432, for postgres server.
From Docker to Host and From Docker to Docker

For OSX, there are several limitations. One is connecting from a container to a service on the host. The workaround is to assign an unused IP address to lo0 and use this IP. Personally, I have sudo ifconfig lo0 alias 192.168.168.167/24. This also solves the inter-docker communication as well. Another limitation is that all docker containers run at the same IP address. The same service on different dockers cannot listen to the same port. The workaround is to use another one and map it.

FROM ubuntu:16.04

RUN apt-get update && apt-get install -y openssh-server

RUN mkdir /var/run/sshd

EXPOSE 22

CMD ["/usr/sbin/ssh", -D]

Generate public and private key pairs and update .ssh/authorized_keys and .ssh/known_hosts.
Update (or double check) that .ssh and its contents are in the correct directory and have correct permissions.

postgres cannot be started as root

CMD postgres fails while CMD ["postgres"] succeeds. Use the docker-entrypoint.sh for postgres-9.6 (by default) or extend it with your own.