Properly override the entrypoint - Saved me a ton of time - https://medium.com/@oprearocks/how-to-properly-override-the-entrypoint-using-docker-run-2e081e5feb9d

sleep container example

$ docker run -d --entrypoint "sleep" openjdk:8 900
e23ed611c217d1038a993b4c9794c27e0363530335c50e2ce26be596301aceb0
$ docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
e23ed611c217        openjdk:8           "sleep 900"         2 seconds ago       Up 1 second                             vigilant_carson
$ docker exec -ti vigilant_carson /bin/bash
root@e23ed611c217:/# ps -ef
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 01:35 ?        00:00:00 sleep 900
root         7     0  1 01:36 pts/0    00:00:00 /bin/bash
root        13     7  0 01:36 pts/0    00:00:00 ps -ef
root@e23ed611c217:/#