This program is PID 1 inside container (not only for docker), for all POSIX-compatible system, but I only tested it with Linux.
you can see the explanation here
Yes, there are other tools like tini, but that tool is too complex in my opinion. I just want to follow UNIX Philosophy Do One Thing and Do It Well
Well, it's very simple, just run
docker_pid1 [the_program] [arg1] [arg2] [... argN]
- create automated testing script