Docker: Move Docker data directory to new location
The standard data directory used for docker is /var/lib/docker, and since this directory will store all your images, volumes, etc. it can become quite large.
Follow the steps below to move the Docker data directory to a new location. This makes especially sense if you want to avoid running out of disk space on your root partition.
Stop the Docker daemon.
sudo service docker stop
Create a config file /etc/docker/daemon.json
{
"data-root": "/mnt/sdb/docker"
}
Copy the current directory to the new directory.
sudo rsync -a /var/lib/docker /mnt/sdb/docker
Rename the old directory.
sudo mv /var/lib/docker /var/lib/docker.old
Restart the Docker deamon.
sudo service docker start
Test if all services work as expected.
docker ps -a
docker info -f '{{ .DockerRootDir}}'
If everything is good, remove the old Docker directory.
sudo rm -rf /var/lib/docker.old