Container networking: names and ports

Docker answers with container names in a network you create. Here: how to create one and connect containers to it.

docker network create <name> creates a network of your own. Docker's DNS works in it: the /etc/resolv.conf of each of its containers has nameserver 127.0.0.11, and this server knows the names of every container in the network. A name is visible only inside the network: a container from another network will not find it.

A container joins a network when it is created — with the --network option of docker run — or on the fly, with docker network connect: no restart is needed for that. A container can be in several networks.

sudo docker network create backnet          # a network of your own
sudo docker run -d --name worker --network backnet busybox sleep 600
sudo docker network connect backnet cache   # connect a running one
sudo docker network inspect backnet         # who is in it, addresses