Stop docker service and socket
sudo systemctl stop docker.service && \
sudo systemctl stop docker.socket
Edit the current configuration
sudo nano /lib/systemd/system/docker.service
Locate: ExecStart
and add the follwing line: -g /some/other/location
Ensure that the directory exits
sudo mkdir -p /some/other/location
Sync pre-existing content
sudo rsync -aqxP /var/lib/docker/ /some/other/location
Start docker service and socket
sudo systemctl daemon-reload && \
sudo systemctl start docker