Image Cleanup
1.Display the storage space being used by Docker.
docker system df
2.Display disk usage by individual objects.
docker system df -v
3.Delete dangling images (images with no tags or containers).
docker image prune
4.Pull an image not being used by any containers, and use docker image prune -a to clean up all images with no containers.
docker image pull nginx:1.14.0
docker image prune -a