Docker 101 – Bind mounts or Volumes

This article is written for docker beginners to understand bind mounts and volumes and how to choose between them.

Bind mounts

  • A file or directory on the host machine is mounted into a container, it is created on demand if it does not yet exist
  • If you bind-mount to a non-empty directory in the container, that directory’s existing contents will be obscured by your directory on the host file system
  • Changes in the local directory will propagate to the bind-mounted directory in the container
  • Changes in the bind-mounted directory in the container also will propagate back to the local directory

Volumes

  • A new directory is created within Docker’s storage directory on the host machine, and Docker manages that directory’s contents
  • If you expose a container directory as a volume, its contents are copied into the volume on the host
  • Volumes are often a better choice than persisting data in a container’s writable layer, because a volume does not increase the size of the containers using it
  • Volumes are easier to back-up or migrate than bind mounts and can be more safely shared among multiple containers

How to Choose

They can be used in different situations. While both options offer a way to data persistence, I would suggest using volumes over bind mounts in normal situations as they are more stable to work with and support more functionalities. But if you are developing a system where you want to easily edit files on the local file system, bind mounts are more convenient in doing that.

Published by Mageek

Just another geek in the world

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