Comment 4 for bug 1891530

Based on internal discussions and investigation, so far there have been 4 ideas brought up:

1) Prevent snaps from automatically being updating themselves

a) Use Enterprise Snap Proxy
b) Snap devmode

2) Delaying the snap update up to 90 days

3) Have better notifications

a) Release notes indicating image updates on each new point release
b) Integrate to the LMA stack for alerts on snap/image list/point releases

4) Automatically detect the problem and do not do the upgrade

Approach #1 allows for the operator to allow the updates to occur in a scheduled maintenance window
Approach #2 and/or #3 allows the operator to create a cronjob or script that monitors upstream release notes or the image list [1] for changes and pull the new images to the custom registry
Approach #4 seems to be the ideal one. By using snap hooks [2], a validation of whether the required images are accessible can be coded in the snap to prevent the daemonsets yamls from being updated to seek new images, therefore preventing the ImagePullBackOff state. Also as part of it, a message could be triggered to inform the user that the new required images have not been found.

[1] https://github.com/charmed-kubernetes/bundle/blob/master/container-images.txt
[2] https://forum.snapcraft.io/t/supported-snap-hooks/3795