It's better to have it the other way around. Attempt to boot off the network and fall back to local drive. That will allow you to reimage a node without having to fiddle with the BIOS. For regular boot there should be no image configured. Network boot will fail and the node will boot off disk. However if an install image is configured for that node, you can reimage it at will. The install image should reset to having no image for that node, once it's done.

You'll need to maintain an association between - dns, ip, mac address, ssh keys etc.

Hardware break-fix workflow is usually ignored by most production engineers. You'll be doing that a lot. You want to get your hw back into use as fast as possible.

Have you thought about how many spares (CPU, RAM, disks) you'll have to keep at your datacenters ?

Thanks, added to the article with https://gitlab.com/gitlab-com/www-gitlab-com/commit/ef3c7e1c... (will take some minutes to roll out).

And memtest86.