Deprecate and remove the Shutdown Room Admin API in favour of the Delete Room API

[anoadragon453]

The delete room admin API covers all of the functionality of the shutdown room admin API and more.

Instead of having two endpoints that do roughly the same thing, we should deprecate the less useful one.

A deprecation warning will need to go out in the changelog, to allow people to update their third-party code before we eventually remove the API altogether.

[FanchTheSystem]

Maybe shutdown api should be modified to allow room admin to close a room and redirect to a new room.
Without the need to be a server admin, only the room admin right should be enough (because you can be the admin of a room which is not on your server).

For example if I have two (or more) room about the same subject, and I want to close some, I would want the user in my "old" room to be notified that it is closed and where the new room is. (like when you upgrade a room)
In this case, the old room will not have to be purged, as you will want to keep the history.

I think it is a very common use case, as when people discover matrix, most of time they create a lot of room, and when they make some friend they find that those friend have already created room with the same kind of topic. So one day they want to re-organize their common room and close duplicate one.

[anoadragon453]

@FanchTheSystem that should probably be the decision of the room admin, rather than a server admin? At the moment we use manual room upgrades to redirect users of a room into another - though the process is indeed quite manual and cannot be done with the GUI in any client at the moment. Plus a "room upgrade" isn't exactly the wording users would expect in this situation.

[FanchTheSystem]

@anoadragon453 Yes it is my point, instead of removing "Shutdown Room" from server admin api, it should be transferred to normal api for room admin usage ;) (ie use a room admin token for the curl call)

[anoadragon453]

@FanchTheSystem I think that should be discussed on a separate issue. This issue is intended to express that the functionality of the shutdown room admin API has been superseded by the delete room admin API, and we should remove the former as it is currently redundant.

An addition for room admins to do something similar is a good idea, but one that would work in a fundamentally different way internally (you'd need to spec a state event that all servers in the room would agree on). That should be done outside of this issue, which is confined to Synapse's admin API.

[FanchTheSystem]

@anoadragon453 You're right, I created a feature request fot it ;)
Thank you !

[dklimpel]

Related: #8810

[anoadragon453]

This has been done in #8829.