kubectl explain template fails when array includes boolean value

[ardaguclu]

What happened:

apply the example CRD and running kubectl explain fails with;

CRD

```yaml apiVersion: apiextensions.k8s.io/v1 kind: CustomResourceDefinition metadata: name: mock-resources.test.tectonic.com spec: group: test.tectonic.com scope: Namespaced names: plural: mock-resources singular: mock-resource kind: MockResource listKind: MockResources versions: - name: v1 storage: true served: true schema: openAPIV3Schema: type: object properties: status: type: object properties: statuses: type: object properties: status1: type: string status2: type: string podStatuses: type: object additionalProperties: type: array items: type: string otherStatuses: type: object additionalProperties: type: array items: type: string customConditions: type: array items: type: object properties: lastTransitionTime: type: string lastUpdateTime: type: string message: type: string reason: type: string status: type: string type: type: string otherCustomConditions: type: array items: type: object properties: lastTransitionTime: type: string lastUpdateTime: type: string message: type: string reason: type: string status: type: string type: type: string additionalProperties: true spec: type: object required: - password - select properties: password: type: string minLength: 1 maxLength: 25 pattern: "^[a-zA-Z0-9._\\-%]*$" number: type: integer minimum: 2 maximum: 4 select: type: string fieldGroup: type: object description: "[SCHEMA] field group - Quis cupidatat in sint occaecat quis dolore irure ea minim sint aliquip nisi aliquip." title: "[SCHEMA] Field Group" properties: itemOne: type: string itemTwo: type: integer arrayFieldGroup: type: array title: "[SCHEMA] Array Field Group" description: "[SCHEMA] array field group - Quis excepteur nostrud qui sunt reprehenderit reprehenderit deserunt eu aute laboris id aliqua." items: type: object properties: itemOne: type: string itemTwo: type: integer hiddenFieldGroup: type: object properties: hiddenItem: type: object podCount: type: integer endpointList: type: array items: type: object additionalProperties: true resourceRequirements: type: object additionalProperties: true k8sResourcePrefix: type: string booleanSwitch: type: boolean checkbox: type: boolean imagePullPolicy: type: string updateStrategy: type: object additionalProperties: true text: type: string nodeAffinity: type: object additionalProperties: true podAffinity: type: object additionalProperties: true podAntiAffinity: type: object additionalProperties: true advanced: type: string fieldDependencyControl: type: boolean fieldDependency: type: string nestedFieldDependency: type: object properties: enabled: type: boolean settings: type: object properties: enabled: type: boolean arrayFieldDependency: type: array items: type: object properties: enabled: type: boolean dependent: type: string hidden: type: string objectWithArray: type: object properties: name: type: string tags: type: array items: type: string birthday: type: object properties: month: type: number day: type: number year: type: number arrayWithObject: type: array items: type: object properties: organization: type: object properties: name: type: string address: type: object properties: street: type: string city: type: string state: type: string current: type: boolean resourceRequirements: type: object properties: {} deeplyNested: type: object properties: foo: type: object properties: bar: type: object properties: baz: type: object properties: bat: type: object additionalProperties: true ```

GROUP:      test.tectonic.com
KIND:       MockResource
VERSION:    v1

error: template: plaintext:39:13: executing "plaintext" at <include "schema" (dict "gvk" $gvk "Document" $.Document "FieldPath" $.FieldPath "Recursive" $.Recursive)>: error calling include: template: plaintext:63:21: executing "schema" at <include "output" (set $ "schema" .)>: error calling include: template: plaintext:101:17: executing "output" at <include "fieldList" (dict "schema" $resolved "level" 1 "Document" $.Document "Recursive" $.Recursive)>: error calling include: template: plaintext:257:15: executing "typeGuess" at <.items>: can't evaluate field items in type bool

What you expected to happen:

kubectl explain properly renders the CRD to template

How to reproduce it (as minimally and precisely as possible): Apply CRD and run kubectl explain

Anything else we need to know?:

Environment:

• Kubernetes client and server versions (use kubectl version): 1.28, 1.29, 1.30
• Cloud provider or hardware configuration:
• OS (e.g: cat /etc/os-release):

[ardaguclu]

I verified that CRD is successfully applied to API server.

/triage accepted /priority backlog

@alexzielenski @ah8ad3 do you have any insights about how to troubleshoot this?. I spent some time on it but couldn't sort out. Thanks.

[ah8ad3]

Thanks for raising this issue Arda. Tested it with some CRD's few months ago and it worked fine, i will take a look at this. I will add my finding and troubleshoot after i can reproduce it.

[alexzielenski]

I haven’t dug too deeply into it my guess would be that the problem is your schema uses ‘additionalProperties: true’ while the template assumes it is always a schema in a few places:

https://github.com/kubernetes/kubectl/blob/d0e936c703558421df2ef367a7c8c1c5972e5c3c/pkg/explain/v2/templates/plaintext.tmpl#L185

the template should be changed to handle/ignore bool case

[ah8ad3]

@ardaguclu After some debugging i find out if you remove line 77 of schema. It would work fine.

[ah8ad3]

Thanks @alexzielenski, code wants to iterate over true value of additionalProperties. I can fix that if you want.

[alexzielenski]

That’d be helpful, thanks @ah8ad3 !

/assign @ah8ad3

[ardaguclu]

Thanks a lot for taking care of this.