Clusterclass variables

[mantis-toboggan-md]

This PR adds components to generate form elements from clusterclass variable definitions. I used this modified docker quickstart clusterclass to test all input and validation options:

apiVersion: cluster.x-k8s.io/v1beta1
kind: ClusterClass
metadata:
  name: 'quickstart-more-variables'
  namespace: default
spec:
  controlPlane:
    machineInfrastructure:
      ref:
        apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
        kind: DockerMachineTemplate
        name: quick-start-control-plane
        namespace: default
    metadata: {}
    ref:
      apiVersion: controlplane.cluster.x-k8s.io/v1beta1
      kind: KubeadmControlPlaneTemplate
      name: quick-start-control-plane
      namespace: default
  infrastructure:
    ref:
      apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
      kind: DockerClusterTemplate
      name: quick-start-cluster
      namespace: default
  patches:
    - definitions:
        - jsonPatches:
            - op: add
              path: >-
                /spec/template/spec/kubeadmConfigSpec/clusterConfiguration/imageRepository
              valueFrom:
                variable: imageRepository
          selector:
            apiVersion: controlplane.cluster.x-k8s.io/v1beta1
            kind: KubeadmControlPlaneTemplate
            matchResources:
              controlPlane: true
      description: Sets the imageRepository used for the KubeadmControlPlane.
      enabledIf: '{{ ne .imageRepository "" }}'
      name: imageRepository
    - definitions:
        - jsonPatches:
            - op: add
              path: /spec/template/spec/kubeadmConfigSpec/clusterConfiguration/etcd
              valueFrom:
                template: |
                  local:
                    imageTag: {{ .etcdImageTag }}
          selector:
            apiVersion: controlplane.cluster.x-k8s.io/v1beta1
            kind: KubeadmControlPlaneTemplate
            matchResources:
              controlPlane: true
      description: Sets tag to use for the etcd image in the KubeadmControlPlane.
      name: etcdImageTag
    - definitions:
        - jsonPatches:
            - op: add
              path: /spec/template/spec/kubeadmConfigSpec/clusterConfiguration/dns
              valueFrom:
                template: |
                  imageTag: {{ .coreDNSImageTag }}
          selector:
            apiVersion: controlplane.cluster.x-k8s.io/v1beta1
            kind: KubeadmControlPlaneTemplate
            matchResources:
              controlPlane: true
      description: Sets tag to use for the etcd image in the KubeadmControlPlane.
      name: coreDNSImageTag
    - definitions:
        - jsonPatches:
            - op: add
              path: /spec/template/spec/customImage
              valueFrom:
                template: >
                  kindest/node:{{ .builtin.machineDeployment.version | replace
                  "+" "_" }}
          selector:
            apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
            kind: DockerMachineTemplate
            matchResources:
              machineDeploymentClass:
                names:
                  - default-worker
        - jsonPatches:
            - op: add
              path: /spec/template/spec/customImage
              valueFrom:
                template: >
                  kindest/node:{{ .builtin.controlPlane.version | replace "+"
                  "_" }}
          selector:
            apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
            kind: DockerMachineTemplate
            matchResources:
              controlPlane: true
      description: >-
        Sets the container image that is used for running dockerMachines for the
        controlPlane and default-worker machineDeployments.
      name: customImage
    - definitions:
        - jsonPatches:
            - op: add
              path: >-
                /spec/template/spec/kubeadmConfigSpec/clusterConfiguration/apiServer/extraArgs
              value:
                admission-control-config-file: /etc/kubernetes/kube-apiserver-admission-pss.yaml
            - op: add
              path: >-
                /spec/template/spec/kubeadmConfigSpec/clusterConfiguration/apiServer/extraVolumes
              value:
                - hostPath: /etc/kubernetes/kube-apiserver-admission-pss.yaml
                  mountPath: /etc/kubernetes/kube-apiserver-admission-pss.yaml
                  name: admission-pss
                  pathType: File
                  readOnly: true
            - op: add
              path: /spec/template/spec/kubeadmConfigSpec/files
              valueFrom:
                template: |
                  - content: |
                      apiVersion: apiserver.config.k8s.io/v1
                      kind: AdmissionConfiguration
                      plugins:
                      - name: PodSecurity
                        configuration:
                          apiVersion: pod-security.admission.config.k8s.io/v1{{ if semverCompare "< v1.25" .builtin.controlPlane.version }}beta1{{ end }}
                          kind: PodSecurityConfiguration
                          defaults:
                            enforce: "{{ .podSecurityStandard.enforce }}"
                            enforce-version: "latest"
                            audit: "{{ .podSecurityStandard.audit }}"
                            audit-version: "latest"
                            warn: "{{ .podSecurityStandard.warn }}"
                            warn-version: "latest"
                          exemptions:
                            usernames: []
                            runtimeClasses: []
                            namespaces: [kube-system]
                    path: /etc/kubernetes/kube-apiserver-admission-pss.yaml
          selector:
            apiVersion: controlplane.cluster.x-k8s.io/v1beta1
            kind: KubeadmControlPlaneTemplate
            matchResources:
              controlPlane: true
      description: Adds an admission configuration for PodSecurity to the kube-apiserver.
      enabledIf: '{{ .podSecurityStandard.enabled }}'
      name: podSecurityStandard
  variables:
    - name: imageRepository
      required: true
      schema:
        openAPIV3Schema:
          default: ''
          description: >-
            imageRepository sets the container registry to pull images from. If
            empty, nothing will be set and the from of kubeadm will be used.
          example: registry.k8s.io
          type: string
    - name: etcdImageTag
      required: true
      schema:
        openAPIV3Schema:
          default: ''
          description: etcdImageTag sets the tag for the etcd image.
          example: 3.5.3-0
          type: string
    - name: coreDNSImageTag
      required: true
      schema:
        openAPIV3Schema:
          default: ''
          description: coreDNSImageTag sets the tag for the coreDNS image.
          example: v1.8.5
          type: string
    - name: podSecurityStandard
      required: false
      schema:
        openAPIV3Schema:
          properties:
            audit:
              default: restricted
              description: >-
                audit sets the level for the audit PodSecurityConfiguration
                mode. One of privileged, baseline, restricted.
              type: string
            enabled:
              default: true
              description: >-
                enabled enables the patches to enable Pod Security Standard via
                AdmissionConfiguration.
              type: boolean
            enforce:
              default: baseline
              description: >-
                enforce sets the level for the enforce PodSecurityConfiguration
                mode. One of privileged, baseline, restricted.
              type: string
            warn:
              default: restricted
              description: >-
                warn sets the level for the warn PodSecurityConfiguration mode.
                One of privileged, baseline, restricted.
              type: string
          type: object
    - name: string-required
      required: true
      schema:
        openAPIV3Schema:
          default: us-east-1
          description: This string has only required validation
          type: string
    - name: string-min-length
      required: true
      schema:
        openAPIV3Schema:
          default: default
          description: >-
            this string has a rule that its length must be greater than or equal
            to 3
          example: sshkeyexample
          minLength: 3
          type: string
    - name: string-max-length
      required: true
      schema:
        openAPIV3Schema:
          default: t3.large
          description: >-
            this string has a rule that its length must be less than or equal to
            10
          maxLength: 10
          type: string
    - name: string-min-max-length
      required: true
      schema:
        openAPIV3Schema:
          default: t3.large
          description: this string has a rules that its length must be between 3 and 10
          maxLength: 10
          minLength: 3
          type: string
    - name: string-pattern
      required: true
      schema:
        openAPIV3Schema:
          default: abc-123
          description: this string must match the pattern /^[a-z]+-[0-9]+$/
          example: zz-00
          pattern: ^[a-z]+-[0-9]+$
          type: string
    - name: string-no-validate
      required: false
      schema:
        openAPIV3Schema:
          default: t3.large
          description: this string has no validation
          type: string
    - name: number-exclusive-min-max
      required: false
      schema:
        openAPIV3Schema:
          default: 3
          description: this string has exclusive min max of 2 and 5
          exclusiveMaximum: true
          exclusiveMinimum: true
          maximum: 5
          minimum: 2
          type: number
    - name: number-inclusive-min-max
      required: false
      schema:
        openAPIV3Schema:
          default: 3
          description: this string has inclusive min max of 2 and 5
          maximum: 5
          minimum: 2
          type: number
    - name: testBoolean
      required: true
      schema:
        openAPIV3Schema:
          description: This is a test value
          type: boolean
    - name: testArrayStrings-min
      required: false
      schema:
        openAPIV3Schema:
          description: This array must have at least 3 items
          items:
            type: string
          minItems: 3
          type: array
    - name: testArrayStrings-max
      required: false
      schema:
        openAPIV3Schema:
          description: This array must have at most 5 items
          items:
            type: string
          maxItems: 5
          type: array
    - name: enums
      required: false
      schema:
        openAPIV3Schema:
          description: This is a string type with enum defined
          enum:
            - option_1
            - option_2
            - option_3
          type: string
    - name: enums-multi
      required: false
      schema:
        openAPIV3Schema:
          description: >-
            This is an array type with enum defined. It may have at most two
            elements
          items:
            type: string
          maxItems: 2
          type: array
    - name: enums-object
      required: false
      schema:
        openAPIV3Schema:
          description: This is an object type with enum defined
          enum:
            - option_1: '1'
            - option_2: '2'
            - option_3: '3'
          type: object
  workers:
    machineDeployments:
      - class: default-worker
        template:
          bootstrap:
            ref:
              apiVersion: bootstrap.cluster.x-k8s.io/v1beta1
              kind: KubeadmConfigTemplate
              name: quick-start-default-worker-bootstraptemplate
              namespace: default
          infrastructure:
            ref:
              apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
              kind: DockerMachineTemplate
              name: quick-start-default-worker-machinetemplate
              namespace: default
          metadata: {}

[mantis-toboggan-md]

I updated this PR to add (limited) support for machine deployment variable overrides. It's limited because I don't think we can reasonably parse variable names if a patch is using valueFrom.template https://cluster-api.sigs.k8s.io/tasks/experimental-features/cluster-class/write-clusterclass#using-variable-values-in-json-patches