How does the Docker Volumes mechanism work and how to properly perform data backup and migration?

The Docker Volumes mechanism is the standard and preferred way for persistent storage of data generated and used by containers. Unlike bind-mounts, volumes are fully managed by Docker and isolated from the host filesystem. This makes them independent of the container lifecycle and portable between different execution environments.

Volume backup requires a special approach because the files belong to a directory managed by Docker. The most common way to create a backup is to run a temporary container that mounts the required volume and an archive directory from the host. Using a simple tar command, all data can be packed into a single archive file.

The data restoration process happens in a mirrored way. You create a new empty volume, run a temporary container with the mounted volume, and unpack the previously created archive into it. This approach guarantees data integrity and allows automating the migration processes of databases and configuration files between different servers without stopping core working processes.