Consider splitting this into multiple containers

It is generally recommended that containers only run one service per container, and to avoid one container being responsible for multiple aspects of functionality.

Currently two services and processes are being run in one container within this repository, namely the salt-master and salt-api services and processes. Both of which are started by saltinit.py.

This could instead be replaced by two seperate containers (and potentially images):

version: '3'
services:
  saltmaster:
    image: saltstack/salt:2019.2
    command: salt-master -l debug
    ports:
      - "4505:4505"
      - "4506:4506"
    volumes:
      - ipc_sockets:/var/run/salt/master/
    restart: unless-stopped
  saltapi:
    image: saltstack/salt:2019.2
    command: salt-api -l debug
    volumes:
      - ./api.conf:/etc/salt/master.d/api.conf
      - ipc_sockets:/var/run/salt/master/
    ports:
      - "8000:8000"
    restart: unless-stopped
volumes:
  ipc_sockets: