Comment 1 for bug 1978958

Thank you for the descriptive bug report!

I looked at the code you found [1], and while it is indeed a validation check for volume-backed rescue, it's unfortunately only checked that the required API microversion was requested for volume-backed rescue [2].

That said, I think a validation check of the image metadata could easily be added in that method to fail fast if we know the rescue is not going to work.

[1] https://github.com/openstack/nova/blob/f766db261634c8f95f874ba132159f148de9e8bf/nova/compute/api.py#L4514-L4517
[2] https://github.com/openstack/nova/blob/f766db261634c8f95f874ba132159f148de9e8bf/nova/api/openstack/compute/rescue.py#L60