replacements: Unable to add/create a new array element

[jceb]

Describe the bug

I'd like to copy the host name from an Ingress and use it in a newly created tls section. However, kustomize seems to be unable to create arrays to build the tls section.

Files that can reproduce the issue

ingress.yaml:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: myingress
spec:
  rules:
    - host: myingress.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: my-svc
                port:
                  number: 80

kustomize.yaml:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ingress.yaml

replacements:
  - source:
      kind: Ingress
      name: myingress
      fieldPath: spec.rules.0.host
    targets:
      - select:
          kind: Ingress
          name: myingress
        fieldPaths:
          - spec.tls.0.hosts.0
          - spec.tls.0.secretName
        options:
          create: true

Expected output:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: myingress
spec:
  rules:
    - host: myingress.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: my-svc
                port:
                  number: 80
tls:
  - hosts:
    - myingress.example.com
    secretName: myingress.example.com

Actual output:

Error: accumulating components: accumulateDirectory: "recursed accumulation of path '$PWD': wrong Node Kind for spec.tls expected: SequenceNode was MappingNode: value: {{}}"

Workaround:

Pre-create the tls structure, including a value in hosts, otherwise it won't create the entry.

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

replacements:
  - source:
      kind: Ingress
      name: myingress
      fieldPath: spec.rules.0.host
    targets:
      - select:
          kind: Ingress
          name: myingress
        fieldPaths:
          - spec.tls.0.hosts.0
          - spec.tls.0.secretName
        options:
          create: true
  tls:
    - hosts: ["dummy-entry-to-make-kustomize-replacements-work"]

Expected output

Actual output

Kustomize version

Client Version: version.Info{Major:"1", Minor:"22", GitVersion:"v1.22.6
", GitCommit:"f59f5c2fda36e4036b49ec027e556a15456108f0", GitTreeState:"
archive", BuildDate:"1980-01-01T00:00:00Z", GoVersion:"go1.16.13", Comp
iler:"gc", Platform:"linux/amd64"}

Additional context

• Issue might be related to Allow setting every array element in replacements #4053

[KnVerey]

/triage accepted

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active 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 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 rotten

[jceb]

/remove-lifecycle rotten

[koba1t]

/assign koba1t

[KnVerey]

@koba1t @natasha41575 how do we want this feature to work? I've been thinking about this lately as part of looking into #4561, which is required for the use case in #4761 (the regression is from incorrectly ignoring the invalid paths to a panic--it should throw an error, which will break that person's workflow). In short, I'm wondering if we need to constrain this feature to be able to create only append an array element. To give an extreme example, if they have 2 elements and try to create something in element 100, it doesn't make sense for us to try to create 98 blank elements in the middle. But if they have 2 and they target the 3rd, we have complete knowledge of what the overall array should contain.

Incidentally, you may want to hold off on the implementation until I PR the fix to #4561, which will hopefully be soon. I currently expect that to contain a fairly big change to the transformer, because it surfaces the fact that we're currently splitting the implementation across two different filters, neither of which actually logically should behave the way we need it to for our ultimate feature set.