[markbnj]

> for example, you're very likely to need a few variables defined once and reused across k8s definitions (a host or domain name, project ID, etc). You can't really do that in a DRY way with Kustomize.

I agree this is one of the areas where you feel the pinch of kustomize's rather puritan design philosophy. We've been able to work around those things in ways that aren't exactly elegant, but don't cause physical discomfort. For shared variables we keep a patch on disk and generate specialized copies of it during deployment. It's a hack, but it retains some of the benefits of a declarative approach. We also still use substitution in a couple of places. It's hard to use kustomize to update an image tag that changes with each build for example.