Move Docker data-root

Sun Nov 22 2020

Do you ever feel files in /var/lib/docker are taking so much space of your system partition's storage? That's because the directory is storing docker's images and containers' file-systems, and we all know that those things are really big.

Fortunately, you can actually move docker's data-root to another path by configuring /etc/docker/daemon.jsondaemon configuration file.

WARING: if you are migrating an existing docker data root

Some existing containers may encounter error after migration, you must:

Make sure that everything you want to save has been backed up or persisted out of the container(on host) by mirroring data volumes.
Make sure all containers can be recreated.

It is a good practice to always persist data out of docker container, all containers and images should be seemed as app binaries.

Before You Start

You should stop the docker daemon:

systemctl stop docker

Copy Existing

It is recommended to copy everything instead of moving them, so that you can still find a way back when error occurred.

cp -r /var/lib/docker /path/to/docker/data/root

data-root Configuration

By adding or modifying data-root in /etc/docker/daemon.json, the configuration is done.

{
    "data-root": "/path/to/docker/data/root"
}

Restart