create-setter ignores array type in Kptfile

[shawnzhu]

$ kpt version
0.27.0

Problem

Given:

# input.yaml
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: ml-pipeline-tensorboard-ui
spec:
  gateways:
  - "kubeflow-gateway"
  hosts:
  - '*'

And Kptfile:

kind: Kptfile
openAPI:
  definitions: {}

Run:

$ kpt cfg create-setter tmp/ \
  istio-gateway "kubeflow-gateway" \
  --type array --field "spec.gateways"
$ kpt cfg list-setters tmp/
Error: The input value doesn't validate against provided OpenAPI schema: validation failure list:
istio-gateway in body must be of type array: "string"

While the expected output is:

$ kpt cfg list-setters tmp/
      NAME                       VALUE                  SET BY            DESCRIPTION             COUNT                                  
  istiogateway    [istio-system/istio-ingressgateway]                                             2

Diagnose

When checking Kptfile, I've noticed that it uses value instead of listValues under setter:

# Kptfile
kind: Kptfile
openAPI:
  definitions: {io.k8s.cli.setters.istio-gateway: {type: array, x-k8s-cli: {setter: {
          name: istio-gateway, value: kubeflow-gateway}}}}

While the expected Kptfile should be:

openAPI:
  definitions:
    io.k8s.cli.setters.istiogateway:
      type: array
      x-k8s-cli:
        setter:
          name: istiogateway
          listValues:
          - "istio-system/istio-ingressgateway"

According to https://googlecontainertools.github.io/kpt/guides/producer/setters/#setting-lists

Note: Move the setter reference from the element (- "a") to the list (list: )

another problem is the field reference in updated input.yaml is not in the expected line (should be at the line of gateways:):

Actual result:

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: ml-pipeline-tensorboard-ui
spec:
  gateways:
  - "kubeflow-gateway" # {"$ref":"#/definitions/io.k8s.cli.setters.istio-gateway"}
  hosts:
  - '*'

[shawnzhu]

Discovered when trying to using kpt setter in kubeflow/manifests#1211

[phanimarupaka]

@shawnzhu As mentioned here you should move the reference to the list key and it works fine.

kpt cfg create-setter /tmp istio-gateway "kubeflow-gateway" --type array --field "spec.gateways"

Move the reference and the input.yaml. This is a manual step currently for creating setter for list-item

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: ml-pipeline-tensorboard-ui
spec:
  gateways: # {"$kpt-set":"istio-gateway"}
  - "kubeflow-gateway"
  hosts:
  - '*'

And list-setters works fine

kpt cfg list-setters /tmp
     NAME             VALUE         SET BY   DESCRIPTION   COUNT  
 istio-gateway   kubeflow-gateway                          0   

[shawnzhu]

Note: Currently create-setter will not directly create a setter reference for a list field. The simplest way to create a list setter is to create a setter for one of the elements, and then move the reference to the list field.

@phanimarupaka notes taken, that's the workaround I'm using now. Thanks. But is this by design? b/c there will be lots of work that moves field references from the source YAML.

And list-setters works fine

Looks like the value becomes string instead of array. it's going to be a problem if there're multiple values.