You definitely aren’t alone in wanting this. We’ve had several users of the Rocket.Chat snap ask for this as well. They are just simply used to being able to say Tuesday is update day. Or be able to schedule a down time to alert their users.
I definitely understand where the snap team is coming from though. This is one of major benefits of snaps. The fact that they will be updated. That we as snap publishers can push out a critical vulnerability patch to our users and not have them ignore it. Of course the users get that same peace of mind.
I think if we had mechanisms in place to bring up the new version of the snap and do a more seamless hand off this worry of interruption / downtime would lesson.
I think there are probably several issues here. First by default snaps kill and unmount the previous snap version before mounting and then starting the new version. Secondly… if a network service. You couldn’t even start the second service because you would have a bind conflict.
Anyways… so far i’ve been just telling users that want this level of control to go the manual route because right now snaps aren’t designed for that scenario.