Docker Cookbook - Second Edition

Persisting data using volumes

As we are aware, the container's read–write layer is temporary, and is destroyed when the container is removed. However, there are use cases wherein you will have to preserve the application data beyond the life cycle of the container. For instance, a Docker registry container holds all the images that are pushed to it. If this container is deleted, then we will lose all the images that it was holding. Perhaps, we can resort to the container's commit flow to preserve the data, but it will bloat the image and complicate the container deployment process. The recommended alternative is to persist the application data outside of the container's filesystem, using volumes or a bind mount. We will discuss bind mounts ...