Using skycfg with proto.Any

[michaelkipper]

Related to #14, the generated.proto files in the Kubernetes API contain the metadata. (E.g.: https://github.com/kubernetes/api/blob/master/apps/v1/generated.proto#L221-L233)

Some hackery can extract the GroupVersionKind from the message type, which sucks but is maintainable.

But other Kubernetes resources (e.g. the Istio VirtualService @ https://github.com/istio/api/blob/master/networking/v1alpha3/virtual_service.proto#L119) don't have the ObjectMeta embedded. They rely on other constructs like client-gen to generate the Go struct but never generate the full protobuf message (E.g.: https://github.com/michaelkipper/istio-client-go/blob/master/pkg/apis/networking/v1alpha3/virtual_service.go#L33-L38)

One thought I had was to generate my own Protobuf wrapper:

message KubernetesWrapper {
  string APIVersion = 1 [json_name="apiVersion"];
  string Kind = 2 [json_name="kind"];
  k8s.io.apimachinery.pkg.apis.meta.v1.ObjectMeta ObjectMeta = 3 [json_name="metadata"];
  google.protobuf.Any Spec = 4 [json_name="spec"];
}

That way we could localize the hackery in our .skylib files, rather than in the parser.

The question is, how do we get skycfg to process the google.protobuf.Any message?
Happy to contribute this upstream, if someone can help out with the design.

[jmillikin-stripe]

Closing: support for google.protobuf.Any was implemented in PR #83