Merge Key Language-Independent Type support for YAML anchor/alias

[RE-codes]

Describe the bug

Following up on #3675. I have found anchor/alias support improved. However, when using Merge Key Language-Independent Type notation (i.e. <<: *some_anchor) I am presented with this error:

Error: map[string]interface {}{"apiVersion":"apps/v1", "kind":"Deployment", "metadata":map[string]interface {}{"annotations":map[string]interface {}{"annotation1":"annotation1", "annotation2":"annotation2", "annotation3":"annotation3"}, "labels":map[string]interface {}{"app":"myApp", "label1":"label1", "label2":"label2", "label3":"label3"}, "name":"myApp", "namespace":"app-namespace"}, "spec":map[string]interface {}{"replicas":3, "selector":map[string]interface {}{"matchLabels":map[string]interface {}{"app":"myApp"}}, "template":map[string]interface {}{"copy-of-metadata":map[string]interface {}{"annotations":map[string]interface {}{"annotation1":"annotation1", "annotation2":"annotation2", "annotation3":"annotation3"}, "labels":map[string]interface {}{"app":"myApp", "label1":"label1", "label2":"label2", "label3":"label3"}, "name":"myApp", "namespace":"app-namespace"}, "metadata":map[string]interface {}{"annotations":map[interface {}]interface {}{"annotation1":"annotation1", "annotation2":"annotation2", "annotation3":"annotation3", "annotation4":"annotation4"}, "labels":map[string]interface {}{"app":"myApp", "label1":"label1", "label2":"label2", "label3":"label3"}, "name":"myApp", "namespace":"app-namespace"}, "spec":map[string]interface {}{"containers":[]interface {}{map[string]interface {}{"image":"some-registry/some-namespace/myApp:latest", "name":"myApp"}}, "imagePullSecrets":[]interface {}{map[string]interface {}{"name":"some_secret"}}}}}}: json: unsupported type: map[interface {}]interface {}

Files that can reproduce the issue

kustomization.yaml

resources:
- test-deployment.yaml

test-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata: &meta
  name: &name myApp
  namespace: &ns app-namespace
  annotations: &annotations
    annotation1: annotation1
    annotation2: annotation2
    annotation3: annotation3
  labels: &labels
    app: *name
    label1: label1
    label2: label2
    label3: label3
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myApp
  template:
    copy-of-metadata: *meta
    metadata: 
      name: *name
      namespace: *ns
      labels: *labels
      annotations:
        <<: *annotations
        annotation4: annotation4
    spec:
      imagePullSecrets:
        - name: some_secret
      containers:
        - name: myApp
          image: some-registry/some-namespace/myApp:latest

Expected output

apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    annotation1: annotation1
    annotation2: annotation2
    annotation3: annotation3
  labels:
    app: myApp
    label1: label1
    label2: label2
    label3: label3
  name: myApp
  namespace: app-namespace
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myApp
  template:
    copy-of-metadata:
      annotations:
        annotation1: annotation1
        annotation2: annotation2
        annotation3: annotation3
      labels:
        app: myApp
        label1: label1
        label2: label2
        label3: label3
      name: myApp
      namespace: app-namespace
    metadata:
      annotations:
        annotation1: annotation1
        annotation2: annotation2
        annotation3: annotation3
        annotation4: annotation4
      labels:
        app: myApp
        label1: label1
        label2: label2
        label3: label3
      name: myApp
      namespace: app-namespace
    spec:
      containers:
      - image: some-registry/some-namespace/myApp:latest
        name: myApp
      imagePullSecrets:
      - name: some_secret

Actual output

See error message above.

Kustomize version

{Version:kustomize/v4.4.0 GitCommit:63ec6bdb3d737a7c66901828c5743656c49b60e1 BuildDate:2021-09-27T16:13:36Z GoOs:darwin GoArch:amd64}

Platform

macOS Big Sur

Additional context

The same error is noted in #4212.

[k8s-ci-robot]

@RE-codes: This issue is currently awaiting triage.

SIG CLI takes a lead on issue triage for this repo, but any Kubernetes member can accept issues by applying the triage/accepted label.

The triage/accepted label can be added by org members by writing /triage accepted in a comment.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[natasha41575]

@monopole seems related, possibly a duplicate of #4212. Could you take a look?

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue or PR as fresh with /remove-lifecycle stale
• Mark this issue or PR as rotten with /lifecycle rotten
• Close this issue or PR with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle stale

[natasha41575]

/remove-lifecycle stale

[KnVerey]

Closed by #4383