Pass natural/integer preference args to openapi-to-dhall

[arobertn]

This PR addresses #177 by passing the --preferNaturalInt argument to openapi-to-dhall (under PR dhall-lang/dhall-haskell#2316) and including a list of exceptions that should actually be rendered as Dhall Integer.

The list is set based on the version in nix/nixpkgs.nix.make-dhall-kubernetes(), determined by going through the fields in the kubernetes openapi spec files manually. It turns out that there have been no major additions / removals of such fields that should be Integers within current range of versions 1.12 - 1.22, so the list is the same for all. (If a new Kubernetes version is added and a new entry is not added here, an empty argument will be passed to dhall-openapi which will trigger a build failure.)

The preferred solution in #177 that the Kubernetes project includes integer ranges in their Swagger specs is in-process (kubernetes/kubernetes#105533), but this will solve the issue in the meantime, and is isolated and easily reverted when that comes.

[arobertn]

I've now completed the implementation to utilize the functionality now upstream in dhall-haskell/dhall-openapi and checked that the list of exceptions is in fact the same for all current supported kubernetes versions.

[Gabriella439]

@arobertn: Thank you for doing this!

[arobertn]

Always good to learn something by doing. Any ideas when the next release will happen?

[uthark]

Generated Kubernetes manifests looks wrong.

terminationGracePeriodSeconds is uint64 in upstream, but generated manifests looks like this:

"terminationGracePeriodSeconds":30.0

Same issue with other fields

{"downwardAPI":{"defaultMode":420.0 ...

Default mode should be integer, not a float value.

[Gabriella439]

@uthark: Are you using dhall-to-json to generate the manifests? This seems more likely to be an issue with the Dhall to JSON conversion logic than dhall-kubernetes, because currently the generated types specify Natural, which is correct: https://github.com/dhall-lang/dhall-kubernetes/search?q=terminationGracePeriodSeconds