Empty structs for ConfigSync API

[mikebz]

If one was to import pkg/api/configsync/v1beta1/gitconfig.go and use that to generate config (which is what I am doing). Printing out the object or marshaling it to JSON creates an object that looks like this:

  apiVersion: configsync.gke.io/v1beta1
  kind: RootSync
  metadata:
    name: root-sync
    namespace: config-management-system
  spec:
    git:
      auth: none
      dir: /root-sync
      period: 0s
      privateCertSecret: {}
      repo: https://github.com/mikebz/kpt-samples.git/root-sync
      revision: v6
      secretRef: {}
    override: {}
    sourceType: git

The reason is because these structs are not declared as pointers:

	SecretRef SecretReference `json:"secretRef,omitempty"`
...
	CACertSecretRef SecretReference `json:"caCertSecretRef,omitempty"`

Is there a reason for it?

[karlkfi]

IIRC, this is related to a Golang JSON bug (golang/go#10648) that ignores omitempty on structs. Since the K8s yaml formatter round trips through json, it picks up this bug and always prints {} for empty structs.

Changing the structs to pointers might work around the issue, but it also might break reverse compatibility.

[mikebz]

at this point in time it looks like this is the way "go JSON works" https://stackoverflow.com/questions/18088294/how-to-not-marshal-an-empty-struct-into-json-with-go

I suppose I can try changing the datatypes and seeing what happens.