Cleaning docker overlay2 disk usage

After using docker for a while, one thing that I notice is, the disk space usage on /var/lib/docker/overlay2 is quite high. For jsut 3 running containers, and a couple of images, my overlay2 disk usage is around 30GB, which is quite high. To reclaim back the space, what we can do is to clear off unused containers, images, volumes and other docker components, but that is going to be a daunting task for some.

Fortunately, docker comes with some tools that can ease up our work maintaining the software. The command to run it as per below:

$ docker system prune --all --volumes

This command will clear all unused components in docker, including unused volumes and images, Rest assured that running containers, and images used by running containers will be spared. From the man page, we can see that this command's usage is for cleaning up unused data in docker.