Change docker's default data directory

change-docker-data-directory.sh

# Make sure that we have rsync installed
yum install -y rsync

# Make a copy of original unit file
cp /lib/systemd/system/docker.service /lib/systemd/system/docker.service.orig

# Add data directory string
sed -i 's/\(containerd.sock\)/\1 -g \/opt\/lib\/docker/' /lib/systemd/system/docker.service

# Test files
diff /lib/systemd/system/docker.service /lib/systemd/system/docker.service.orig

# Stop docker service
systemctl stop docker

# Do systemcd daemon-reload as we changed docker.service file   
systemctl daemon-reload

# rsync existing docker data to our new location   
rsync -aqxP /var/lib/docker/ /opt/lib/docker/

# Start docker service   
systemctl start docker