Variable Fieldpath can't reference key name with dashes

[kferrone]

Describe the bug

I have a kustomize variable which was working until a recent update. Now the variables are misbehaving for strange reasons.

Files that can reproduce the issue

Here is the var in my kustomization.yaml

vars:
  - name: ZONE
    objref:
      apiVersion: v1
      kind: PersistentVolume
      name: bitcoind
    fieldref:
      fieldpath: metadata.labels[failure-domain.beta.kubernetes.io/zone]

Then here is the corresponding PV with the label
pv.yaml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: bitcoind
  labels:
    failure-domain.beta.kubernetes.io/region: eu-west-2
    failure-domain.beta.kubernetes.io/zone: eu-west-2a

Expected output

I expect the variable to be able to reference any key even with special characters in the name

Actual output

Error: field specified in var '{ZONE ~G_v1_PersistentVolume {metadata.labels[failure-domain.beta.kubernetes.io/zone]}}' not found in corresponding resource

Kustomize version

{Version:kustomize/v3.9.1 GitCommit:7439f1809e5ccd4677ed52be7f98f2ad75122a93 BuildDate:2020-12-30T00:43:15+00:00 GoOs:darwin GoArch:amd64}

Platform

Tested on Mac and Windows, both had the issue

Additional context

I pretty much determined it's the dash because below works:

vars:
  - name: ZONE
    objref:
      apiVersion: v1
      kind: PersistentVolume
      name: bitcoind
    fieldref:
      fieldpath: metadata.labels[failure_domain.beta.kubernetes.io/zone]

... so long as there are no dashes -, a key can be referenced even with dots and slashes in the name

[Shell32-Natsu]

kustomize/api/internal/wrappy/wnode.go

Line 67 in 735befe

fields := strings.Split(path, ".")

In kustomize version >= v3.9, we just simply split the field path by .. We may improve this in future.

BTW, we are planning to remove var from kustomize. #2052

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[k8s-ci-robot]

@fejta-bot: Closing this issue.

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[diogosilva30]

What is the solution for this?

My ingress:

apiVersion: networking.k8s.io/v1
kind: Ingress
ingressClassName: traefik
metadata:
  name: longhorn-ingress
  annotations:
    external-dns.alpha.kubernetes.io/target: $(DNS)

My replacement:

replacements:
  - source:
      kind: Ingress
      fieldPath: metadata.annotations.dns
      name: longhorn-ingress
    targets:
      - select:
          kind: Ingress
          name: longhorn-ingress
        fieldPaths:
          - metadata.annotations[external-dns.alpha.kubernetes.io/target]

I have tried wrapping it with quotes. No success.

[aeciopires]

I had the same problem and solved it with this tip: #1256 (comment)

I used ~1 to represent a /

(workaround)