Which Port Is My Docker Container Running on?

The left-hand side of the port number mapping is the Docker host port to map to and the right-hand side is the Docker container port number. When you open the browser and navigate to the Docker host on port 8080, you will see Jenkins up and running.

Does Docker use port 8080?

Docker also finds ports you expose with --expose 8080 (assuming you want to expose port 8080). Docker maps all of these ports to a host port within a given epehmeral port range . You can find the configuration for these ports (usually 32768 to 61000) in /proc/sys/net/ipv4/ip_local_port_range .

How do I know if my Docker port is exposed?

Exposed ports are visible when you list your containers with docker ps . They'll show up in the PORTS column, even though they won't actually be accessible outside the container. This gives you a simple way of checking which ports the software inside a container is listening on.