Docker can take a toll on your disk space.

Fortunately you don’t have to keep the files in /var/lib/docker and on certain cloud providers like Digital Ocean it’s cheaper to attach a new block volume than to upgrade a droplet to get more disk space.

After you’ve decided on a location, simply do:

# systemctl stop docker
# mkdir /new/path/docker
# rsync -aqxP /var/lib/docker/ /new/path/docker

Change /lib/systemd/system/docker.service:

ExecStart=/usr/bin/dockerd -g /new/path/docker -H fd://

Then:

# systemctl daemon-reload
# systemctl start docker

When you’ve verified things are working, remove the old docker directory.

# rm -r /var/lib/docker