What are Docker Volumes?

Docker volumes are a mechanism for persisting data independently of the container lifecycle. Since, the data in a container will be deleted once the container is stopped, using Docker volumes ensures the data is stored permenently.

• Volumes are managed by Docker and stored on the host (mostly under /var/lib/docker/volumes).
• Most importantly, it allows the data to be stored, retained and shared between container, suriving container restarts and removals.
• It preferrable to use for stateful applications like databases or file servers where data persistence matters.

Creating and Using Volumes

• Volumes can be created implicitly by Docker when referenced or explicitly using:

  docker volume create <volume_name>
  

• Start a container and mount a volume:

  docker run -it -v <volume_name>:/path/in/container <image:tag>
  

Volume Content Persistence and Sharing

• Files written/modified inside the container at the mount point path persist on the volume.
• When a new container mounts the same volume, it can process the previously stored data.
• Volumes can be mounted read-write (default) or read-only with :ro option:

docker run -it -v <volume_name>:/container/path/:ro <image:tag>

Inspecting and Managing Volumes

• List volumes:

  docker volume ls
  

• Inspect a volume for details like mount point:

  docker volume inspect <volume_name>
  

• Remove a Volume(only when inactive/not being by any containers)

  docker volume rm <volume_name>
  

Thoughts

If you read this posts about Bind Mounts, using Volumes over Bind Mount is a benefit because:

• Volumes provide better data management via Docker CLI (create, inspect remove)
• They are portable and flexible, supporting various storage backend beyond local host paths.
• More suitable for production and complex setups than bind mounts.
• Most importantly, it provides data storage isolation as modifying the data inside volume won’t damage the internal system storage.