Move data of Docker to the new directory.

Change.Docker.Root.Directory.md

Change Docker Root Directory

1. Show docker root directory (default: /var/lib/docker).

docker_root="$(docker info -f '{{ .DockerRootDir }}')"
echo "${docker_root}"

2. Start the docker containers and display the free size of the hard disk where the current docker root directory is located.

docker run -itd --name $USER.$RANDOM --rm -v $PWD:$PWD ubuntu:18.04 bash
docker run -itd --name $USER.$RANDOM --rm -v $PWD:$PWD ubuntu:18.04 bash
sudo df -h

3. Stop all the docker services and docker containers.

sudo systemctl stop docker.service
sudo systemctl stop docker.socket
sudo systemctl stop containerd

4. Create new docker root directory.

new_docker_root="/path/to/new_docker_root"
sudo mkdir -p "${new_docker_root}"

5. Sync data from the old docker root directory to the new docker root directory, and it might take a while. Note that the slash / is required, in other words, the argument "${docker_root}"/ and the argument "${docker_root}" are not same for the command rsync.

sudo rsync -avuqP --delete "${docker_root}"/ "${new_docker_root}"

6. Edit the file /etc/docker/daemon.json. If the file does not exist, create it and add the following information.

{
  "data-root": "/path/to/new_docker_root",
  "storage-driver": "overlay2"
}

7. Restart all the docker services.

sudo systemctl daemon-reload
sudo systemctl start docker

8. Check the new docker root directory and images information.

docker info -f '{{ .DockerRootDir }}'
docker images