Moving the Docker root directory to an encrypted filesystem

How to do that in few steps

Sometimes you need to arrange in a different way your file system. For example because you have a particular partitioning or maybe you are using an encrypted partition. Infact you may want your docker data to be inside an encrypted location. This may be strongly useful for running containers which manage secret data or keys. This is how to do.

Let’s imagine that your encrypted partition is mounted on /opt . First of all, fully stop your docker daemon

sudo systemctl stop docker

Create a new directory dedicated to docker inside the mountpoint of your encrypted filesystem

sudo mkdir -p /opt/new_dir

Now define the data root for docker, by changing the daemon.json file.

sudo vim /etc/docker/daemon.json

Modify or add the following json structure

{
  "data-root": "/opt/new_dir/docker"
}

Checking if all went fine

massmux@augustus:~$ docker info -f '{{ .DockerRootDir}}'
/opt/new_dir/docker

that’s it, all is fine and you can start again the docker daemon. Enjoy and please leave a comment below with your opinions.

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