It might sound a bit pedantic, but kustomize strictly avoids the "Infrastructure as Code" space and stays in the "Infrastructure as Data" space. The main difference is that since it just deals with "data", you can build any higher level tooling on this. One of the major proponents of this idea is Brian Grant from Google. He tweets about this from time to time. Here is a recent one: https://twitter.com/bgrant0607/status/1404461906186833927
Is this distinction really about whether the customisation language is declarative? It seems to me that Dhall has the advantages Brian Grant attributes to "Infrastructure as Data", although it is an executable specification.
