[saynay]

I wrote a tiny one that worked as glue between our application's opinion on how node DNS names should be, and what ExternalDNS controller would accept automatically. When GKE would scale the cluster, or upgrade nodes, it was requiring manual steps to fix the DNS. So, instead of rewriting a ton of code all over in our app, and changing the other environments we were running on, I just wrote a ~100 line controller that would respond to node-add events by annotating the node in a way ExternalDNS would parse, and in turn automatically create DNS entries in the form we wanted.

[vel0city]

I both agree this should exactly be what these kinds of small custom operators should be and also see the nuisance of awkward database triggers bubbling up into the "I dunno why it works, just magic" kind of lost knowledge into how systems actually function.