kubebuilder实践笔记(3) - 修改CRD中的字段

这一篇是在上一篇《kubebuilder实践笔记(2) - 入门体验_湾区的候鸟的博客-优快云博客》成功的基础上，再做一点点变化，给CRD加上几个自定义字段，使用kubebuilder重新生成代码，并部署到K8S中，修改资源对象，并观察自定义Controller里面的日志输出。

学习目标：

CRD加上几个自定义字段，使用kubebuilder重新构建，重新部署。

操作步骤：

第1步：修改guestbook_types.go文件，把GuestbookSpec与GuestbookStatus结构体中，改为下面5个字段。

注意：修改时，要那些注释带上，否则生成代码时会少了一些方法。

第2步：重新生成代码，运行make manifests。

注意：每次修改这个文件都要重新生成。

[root@workstation guestbook]# make manifests
/root/kubebuilder/projects/guestbook/bin/controller-gen rbac:roleName=manager-role crd webhook paths="./..." output:crd:artifacts:config=config/crd/bases
[root@workstation guestbook]# 

第3步：把CRD安装到k8s集群中，执行：make install.

[root@workstation guestbook]# make install
/root/kubebuilder/projects/guestbook/bin/controller-gen rbac:roleName=manager-role crd webhook paths="./..." output:crd:artifacts:config=config/crd/bases
/root/kubebuilder/projects/guestbook/bin/kustomize build config/crd | kubectl apply -f -
customresourcedefinition.apiextensions.k8s.io/guestbooks.webapp.my.domain created

安装完成后，可以看到k8s中的CRD已创建，里面已经有了对上面5个自定义字段的Schema： 

[root@master ~]# kubectl describe crd/guestbooks.webapp.my.domain Name:         guestbooks.webapp.my.domain Namespace:     Labels:       <none> Annotations:  controller-gen.kubebuilder.io/version: v0.8.0 API Version:  apiextensions.k8s.io/v1 Kind:         CustomResourceDefinition Metadata:   Creation Timestamp:  2022-04-01T00:51:08Z   Generation:          1   Managed Fields:     API Version:  apiextensions.k8s.io/v1     Fields Type:  FieldsV1     fieldsV1:       f:status:         f:acceptedNames:           f:kind:           f:listKind:           f:plural:           f:singular:         f:conditions:           k:{"type":"Established"}:             .:             f:lastTransitionTime:             f:message:             f:reason:             f:status:             f:type:           k:{"type":"NamesAccepted"}:             .:             f:lastTransitionTime:             f:message:             f:reason:             f:status:             f:type:     Manager:      Go-http-client     Operation:    Update     Subresource:  status     Time:         2022-04-01T00:51:08Z     API Version:  apiextensions.k8s.io/v1     Fields Type:  FieldsV1     fieldsV1:       f:metadata:         f:annotations:           .:           f:controller-gen.kubebuilder.io/version:           f:kubectl.kubernetes.io/last-applied-configuration:       f:spec:         f:conversion:           .:           f:strategy:         f:group:         f:names:           f:kind:           f:listKind:           f:plural:           f:singular:         f:scope:         f:versions:     Manager:         kubectl-client-side-apply     Operation:       Update     Time:            2022-04-01T00:51:08Z   Resource Version:  743922   UID:               9e84e11e-cd5a-4c2c-a295-5e1a5b38fcbb Spec:   Conversion:     Strategy:  None   Group:       webapp.my.domain   Names:     Kind:       Guestbook     List Kind:  GuestbookList     Plural:     guestbooks     Singular:   guestbook   Scope:        Cluster   Versions:     Name:  v1     Schema:       openAPIV3Schema:         Description:  Guestbook is the Schema for the guestbooks API         Properties:           API Version:             Description:  APIVersion defines the versioned schema of this representation of an object. Servers should convert recognized schemas to the latest internal value, and may reject unrecognized values. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources             Type:         string           Kind:             Description:  Kind is a string value representing the REST resource this object represents. Servers may infer this from the endpoint the client submits requests to. Cannot be updated. In CamelCase. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds             Type:         string           Metadata:             Type:  object           Spec:             Description:  GuestbookSpec defines the desired state of Guestbook             Properties:               Alias:                 Enum:                   Phone                   Address                   Name                 Type:  string               Config Map Name:                 Description:  Name of the ConfigMap for GuestbookSpec's configuration                 Max Length:   15                 Min Length:   1                 Type:         string               Size:                 Description:  Quantity of instances                 Format:       int32                 Maximum:      10                 Minimum:      1                 Type:         integer             Required:               configMapName               size             Type:  object           Status:             Description:  GuestbookStatus defines the observed state of Guestbook             Properties:               Active:                 Description:  PodName of the active Guestbook node.                 Type:         string               Standby:                 Description:  PodNames of the standby Guestbook nodes.                 Items:                   Type:  string                 Type:    array             Required:               active               standby             Type:  object         Type:      object     Served:        true     Storage:       true     Subresources:       Status: Status:   Accepted Names:     Kind:       Guestbook     List Kind:  GuestbookList     Plural:     guestbooks     Singular:   guestbook   Conditions:     Last Transition Time:  2022-04-01T00:51:08Z     Message:               no conflicts found     Reason:                NoConflicts     Status:                True     Type:                  NamesAccepted     Last Transition Time:  2022-04-01T00:51:08Z     Message:               the initial names have been accepted     Reason:                InitialNamesAccepted     Status:                True     Type:                  Established   Stored Versions:     v1 Events:  <none> [root@master ~]#

第4步：运行controller，执行make run。

[root@workstation guestbook]# make run
/root/kubebuilder/projects/guestbook/bin/controller-gen rbac:roleName=manager-role crd webhook paths="./..." output:crd:artifacts:config=config/crd/bases
/root/kubebuilder/projects/guestbook/bin/controller-gen object:headerFile="hack/boilerplate.go.txt" paths="./..."
go fmt ./...
go vet ./...
go run ./main.go
1.6487742857355735e+09	INFO	controller-runtime.metrics	Metrics server is starting to listen	{"addr": ":8080"}
1.6487742857360241e+09	INFO	setup	starting manager
1.6487742857365518e+09	INFO	Starting server	{"path": "/metrics", "kind": "metrics", "addr": "[::]:8080"}
1.6487742857366114e+09	INFO	Starting server	{"kind": "health probe", "addr": "[::]:8081"}
1.6487742857367413e+09	INFO	controller.guestbook	Starting EventSource	{"reconciler group": "webapp.my.domain", "reconciler kind": "Guestbook", "source": "kind source: *v1.Guestbook"}
1.6487742857367685e+09	INFO	controller.guestbook	Starting Controller	{"reconciler group": "webapp.my.domain", "reconciler kind": "Guestbook"}
1.6487742858375282e+09	INFO	controller.guestbook	Starting workers	{"reconciler group": "webapp.my.domain", "reconciler kind": "Guestbook", "worker count": 1}

第5步：打开另一个终端，准备一份自定义资源的yaml文件。 

第6步：应用到K8S中。

[root@workstation samples]# kubectl apply -f 2-cr.yaml 
guestbook.webapp.my.domain/guestbook-sample created
[root@workstation samples]#

第7步：修改自定资源对象。

第8步：回到第1个终端，观察controller输出的日志。

预期结果：

日志里有两段输出，第1段为第6步创建资源对象时的输出，第2段为第7步修改资源对象时的输出。

注：这里使用的controller是上一节改过的controller，所以才会有这种日志输出。

问题：

1）第3步中的kubectl describe crd/guestbooks.webapp.my.domain，看到的第一个字段，为枚举字段，这种字段的用法是什么？