Allow users to define an automatic configuration rollback timeout

[bensmrs]

Is there an existing issue for this?

• There is no existing issue for this feature

What are you currently unable to do

Incus environments are very diverse, and so are the configuration changes that can break them. You can erroneously change an address or bind a PCI device that leads your server to not being reachable, or, if your Incus server is your laptop, mess with its display and other niceties.

What do you think would need to be added

I think a --rollback=<n> flag (defaulting to 30 if the flag is passed with no value) should be added to the client to rollback configuration changes if an explicit prompt is not typed within n seconds.

The way I’d see it implemented is that setting this flag would make the configuration change an Incus operation with an automatic cancellation after n seconds, which gets terminated when the client tells the server that the user confirmed the change (a new endpoint could be used for that).

[stgraber]

So adding a Rollback field to InstancePut or as a ?rollback=X to the URL, then have that spawn an additional background operation upon completion of the existing request/operation and find a way to send that background operation back to the user for them to cancel before the deadline.

Should be possible, just potentially a bit messy for the endpoints that are already a background operation. I don't recall if PUT /1.0/instances/NAME is sync or async.