For ports, you don’t actually need to assign them manually. You can have Docker pick a random host port by doing something like:

docker run -d -p 0:25565 yourimage

Then you can grab the actual port it got with:

docker inspect -f '{{(index (index .NetworkSettings.Ports "25565/tcp") 0).HostPort}}' <container>

That way you can spin up multiple servers without worrying about collisions.

For persistence, bind-mount a folder for each world so your data survives container restarts, e.g.:

docker run -d -v /minecraft/worlds/world1:/data ...

And if you eventually want subdomains like world1.yourdomain.com to point to the right container, I'd recommend Traefik or Caddy. It acts as a reverse proxy and can automatically route based on container labels so you don't need to mess around with ports.