Docker Container Upgrades on Synology

Synology provide great hardware for home storage, and moving up a tier from their budget offering adds a great deal of functionality, including full Docker support.

Inevitably Docker images will require updating; these are some quick notes on how to do that.

Docker Data Storage

Generally speaking, storing state within a docker container is discouraged. As the container could go away at any point, persistant data should be stored outside of it to separate the application from its state.

Docker provides various storage drivers to handle different workloads, each with different performance characteristics.

On Synology systems, Docker uses the Overlay volume to map container directories onto the host device’s file system.

Upgrade Process

This makes the upgrade process very straight forward, simply fire up the Synology Docker application, then:

  1. Goto ‘Registry’, search for the Image you wish to upgrade, and download (this will overwrite the existing version)
  2. Goto ‘Container’, and stop  the container you want to upgrade
  3. Clear the Container
  4. Start Container back up

That’s it, the container should now be on the latest version of the image, with all its previous state persisted.