Got most the information here: [https://docs.docker.com/engine/installation/linux/archlinux/#starting-docker] Initially we need to install docker directly from pacman (official repo, not AUR):
pacman -S docker
After it is installed you just need to run this to start it:
sudo systemctl start docker
Or if you want to have it always on:
sudo systemctl enable docker
All the docker commands need to run on sudo
So if you want to check the IP address of a running container, get the container Id and run this:
sudo docker <container_id> inspect
And search for something like this: "IPAddress": "172.17.0.2"
172.17.0.2 is going to be ip of the first machine running, each container will generate a new IP, it should be sequencial, so the next would be 172.17.0.3