這篇文章主要介紹了kubernetes CRD開發(fā)的示例分析，具有一定借鑒價(jià)值，感興趣的朋友可以參考下，希望大家閱讀完這篇文章之后大有收獲，下面讓小編帶著大家一起了解一下。
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kubebuilder能幫我們節(jié)省大量工作，讓開發(fā)CRD和adminsion webhook變得異常簡單。
通過源碼安裝：
git clone https://github.com/kubernetes-sigs/kubebuilder cd kubebuilder make build cp bin/kubebuilder $GOPATH/bin
或者下載二進(jìn)制：
重慶分公司
重慶分公司
os=$(go env GOOS)
arch=$(go env GOARCH)
# download kubebuilder and extract it to tmp
curl -sL https://go.kubebuilder.io/dl/2.0.0-beta.0/${os}/${arch} | tar -xz -C /tmp/
# move to a long-term location and put it on your path
# (you'll need to set the KUBEBUILDER_ASSETS env var if you put it somewhere else)
sudo mv /tmp/kubebuilder_2.0.0-beta.0_${os}_${arch} /usr/local/kubebuilder
export PATH=$PATH:/usr/local/kubebuilder/bin還需要裝下kustomize 這可是個(gè)渲染yaml的神器，讓helm顫抖。
go install sigs.k8s.io/kustomize/v3/cmd/kustomize
注意你得先有個(gè)kubernetes集群，一步安裝走你
創(chuàng)建CRD
kubebuilder init --domain sealyun.com --license apache2 --owner "fanux" kubebuilder create api --group infra --version v1 --kind VirtulMachine
安裝CRD并啟動controller
make install # 安裝CRD make run # 啟動controller
然后我們就可以看到創(chuàng)建的CRD了
# kubectl get crd NAME AGE virtulmachines.infra.sealyun.com 52m
來創(chuàng)建一個(gè)虛擬機(jī)：
# kubectl apply -f config/samples/ # kubectl get virtulmachines.infra.sealyun.com NAME AGE virtulmachine-sample 49m
看一眼yaml文件：
# cat config/samples/infra_v1_virtulmachine.yaml apiVersion: infra.sealyun.com/v1 kind: VirtulMachine metadata: name: virtulmachine-sample spec: # Add fields here foo: bar
這里僅僅是把yaml存到etcd里了，我們controller監(jiān)聽到創(chuàng)建事件時(shí)啥事也沒干。
把controller部署到集群中
make docker-build docker-push IMG=fanux/infra-controller make deploy
我是連的遠(yuǎn)端的kubenetes, make docker-build時(shí)test過不去，沒有etcd的bin文件，所以先把test關(guān)了。
修改Makefile:
# docker-build: test docker-build:
Dockerfile里的gcr.io/distroless/static:latest 這個(gè)鏡像你也可能拉不下來，隨意改改就行，我改成了golang:1.12.7
也有可能構(gòu)建時(shí)有些代碼拉不下來，啟用一下go mod vendor 把依賴打包進(jìn)去
go mod vendor 如果你本地有些代碼拉不下來，可以用proxy:
export GOPROXY=https://goproxy.io
再改下Dockerfile, 注釋掉download：
修改后：
# Build the manager binary FROM golang:1.12.7 as builder WORKDIR /go/src/github.com/fanux/sealvm # Copy the Go Modules manifests COPY . . # Build RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o manager main.go # Use distroless as minimal base image to package the manager binary # Refer to https://github.com/GoogleContainerTools/distroless for more details # FROM gcr.io/distroless/static:latest FROM golang:1.12.7 WORKDIR / COPY --from=builder /go/src/github.com/fanux/sealvm/manager . ENTRYPOINT ["/manager"]
make deploy 時(shí)報(bào)錯(cuò)： Error: json: cannot unmarshal string into Go struct field Kustomization.patches of type types.Patch
把 config/default/kustomization.yaml 中的 patches: 改成 patchesStrategicMerge: 即可
kustomize build config/default 這個(gè)命令就渲染出了controller的yaml文件，可以體驗(yàn)下
看 你的controller已經(jīng)跑起來了：
kubectl get deploy -n sealvm-system NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE sealvm-controller-manager 1 1 1 0 3m kubectl get svc -n sealvm-system NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE sealvm-controller-manager-metrics-service ClusterIP 10.98.71.1998443/TCP 4m
看下config/samples下面的yaml文件：
apiVersion: infra.sealyun.com/v1 kind: VirtulMachine metadata: name: virtulmachine-sample spec: # Add fields here foo: bar
這里參數(shù)里有foo:bar， 那我們來加個(gè)虛擬CPU，內(nèi)存信息：
直接api/v1/virtulmachine_types.go即可
// VirtulMachineSpec defines the desired state of VirtulMachine
// 在這里加信息
type VirtulMachineSpec struct {
// INSERT ADDITIONAL SPEC FIELDS - desired state of cluster
// Important: Run "make" to regenerate code after modifying this file
CPU string `json:"cpu"` // 這是我增加的
Memory string `json:"memory"`
}
// VirtulMachineStatus defines the observed state of VirtulMachine
// 在這里加狀態(tài)信息，比如虛擬機(jī)是啟動狀態(tài)，停止?fàn)顟B(tài)啥的
type VirtulMachineStatus struct {
// INSERT ADDITIONAL STATUS FIELD - define observed state of cluster
// Important: Run "make" to regenerate code after modifying this file
}然后make一下：
make && make install && make run
這時(shí)再去渲染一下controller的yaml就會發(fā)現(xiàn)CRD中已經(jīng)帶上CPU和內(nèi)存信息了：
kustomize build config/default
properties: cpu: description: 'INSERT ADDITIONAL SPEC FIELDS - desired state of cluster Important: Run "make" to regenerate code after modifying this file' type: string memory: type: string
修改一下yaml:
apiVersion: infra.sealyun.com/v1 kind: VirtulMachine metadata: name: virtulmachine-sample spec: cpu: "1" memory: "2G"
# kubectl apply -f config/samples
virtulmachine.infra.sealyun.com "virtulmachine-sample" configured
# kubectl get virtulmachines.infra.sealyun.com virtulmachine-sample -o yaml
apiVersion: infra.sealyun.com/v1
kind: VirtulMachine
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"infra.sealyun.com/v1","kind":"VirtulMachine","metadata":{"annotations":{},"name":"virtulmachine-sample","namespace":"default"},"spec":{"cpu":"1","memory":"2G"}}
creationTimestamp: 2019-07-26T08:47:34Z
generation: 2
name: virtulmachine-sample
namespace: default
resourceVersion: "14811698"
selfLink: /apis/infra.sealyun.com/v1/namespaces/default/virtulmachines/virtulmachine-sample
uid: 030e2b9a-af82-11e9-b63e-5254bc16e436
spec: # 新的CRD已生效
cpu: "1"
memory: 2GStatus 同理，就不再贅述了，比如我把status里加一個(gè)Create, 表示controller要去創(chuàng)建虛擬機(jī)了(主要一些控制層面的邏輯)，創(chuàng)建完了把狀態(tài)改成Running
controller把輪訓(xùn)與事件監(jiān)聽都封裝在這一個(gè)接口里了.你不需要關(guān)心怎么事件監(jiān)聽的.
func (r *VirtulMachineReconciler) Reconcile(req ctrl.Request) (ctrl.Result, error) {
ctx = context.Background()
_ = r.Log.WithValues("virtulmachine", req.NamespacedName)
vm := &v1.VirtulMachine{}
if err := r.Get(ctx, req.NamespacedName, vm); err != nil { # 獲取VM信息
log.Error(err, "unable to fetch vm")
} else {
fmt.Println(vm.Spec.CPU, vm.Spec.Memory) # 打印CPU內(nèi)存信息
}
return ctrl.Result{}, nil
}make && make install && make run這個(gè)時(shí)候去創(chuàng)建一個(gè)虛擬機(jī)kubectl apply -f config/samples,日志里就會輸出CPU內(nèi)存了. List接口同理，我就不贅述了
r.List(ctx, &vms, client.InNamespace(req.Namespace), client.MatchingField(vmkey, req.Name))
在status結(jié)構(gòu)體中加入狀態(tài)字段：
type VirtulMachineStatus struct {
Status string `json:"status"`
}controller里去更新狀態(tài)：
vm.Status.Status = "Running"
if err := r.Status().Update(ctx, vm); err != nil {
log.Error(err, "unable to update vm status")
}如果出現(xiàn):the server could not find the requested resource 這個(gè)錯(cuò)誤，那么在CRD結(jié)構(gòu)體上需要加個(gè)注釋 // +kubebuilder:subresource:status：
// +kubebuilder:subresource:status
// +kubebuilder:object:root=true
type VirtulMachine struct {
metav1.TypeMeta `json:",inline"`
metav1.ObjectMeta `json:"metadata,omitempty"`
Spec VirtulMachineSpec `json:"spec,omitempty"`
Status VirtulMachineStatus `json:"status,omitempty"`
}這樣就好了
編譯啟動后再去apply發(fā)現(xiàn)狀態(tài)已經(jīng)變成running：
# kubectl get virtulmachines.infra.sealyun.com virtulmachine-sample -o yaml ... status: status: Running
time.Sleep(time.Second * 10)
if err := r.Delete(ctx, vm); err != nil {
log.Error(err, "unable to delete vm ", "vm", vm)
}10s之后我們將GET不到
如果不使用Finalizers，kubectl delete 時(shí)直接就刪了etcd數(shù)據(jù)，controller再想去拿CRD時(shí)已經(jīng)拿不到了：
ERRO[0029] VirtulMachine.infra.sealyun.com "virtulmachine-sample" not foundunable to fetch vm source="virtulmachine_controller.go:48"
所以在創(chuàng)建時(shí)我們需要給CRD加上Finalizer:
vm.ObjectMeta.Finalizers = append(vm.ObjectMeta.Finalizers, "virtulmachine.infra.sealyun.com")
然后刪除時(shí)就只會給CRD打上一個(gè)刪除時(shí)間戳，供我們做后續(xù)處理, 處理完了我們刪除掉Finalizers：
如果 DeleteionTimestamp不存在 如果沒有Finalizers 加上Finalizers,并更新CRD 要不然，說明是要被刪除的 如果存在Finalizers，刪除Finalizers,并更新CRD
看個(gè)完整的代碼示例：
if cronJob.ObjectMeta.DeletionTimestamp.IsZero() {
if !containsString(cronJob.ObjectMeta.Finalizers, myFinalizerName) {
cronJob.ObjectMeta.Finalizers = append(cronJob.ObjectMeta.Finalizers, myFinalizerName)
if err := r.Update(context.Background(), cronJob); err != nil {
return ctrl.Result{}, err
}
}
} else {
if containsString(cronJob.ObjectMeta.Finalizers, myFinalizerName) {
if err := r.deleteExternalResources(cronJob); err != nil {
return ctrl.Result{}, err
}
cronJob.ObjectMeta.Finalizers = removeString(cronJob.ObjectMeta.Finalizers, myFinalizerName)
if err := r.Update(context.Background(), cronJob); err != nil {
return ctrl.Result{}, err
}
}
}假設(shè)我們A依賴B而B又后創(chuàng)建，那么在處理A CRD時(shí)直接返回失敗即可，這樣很快會重試
kuberentes有三種webhook,admission webhook, authorization webhook and CRD conversion webhook.
這里比如我們要給CRD設(shè)置一些默認(rèn)值，又或者是用戶創(chuàng)建時(shí)少填了一些參數(shù)，那么我們得禁止創(chuàng)建等等這些事。
使用webhook也非常的簡單，只需給定義的結(jié)構(gòu)體實(shí)現(xiàn) Defaulter 和 Validator接口即可.
Reconcile結(jié)構(gòu)體聚合了Client接口，所以client的所有方法都是可以直接調(diào)用，大部分是對CRD object的相關(guān)操作
type Client interface {
Reader
Writer
StatusClient
}// Reader knows how to read and list Kubernetes objects.
type Reader interface {
// Get retrieves an obj for the given object key from the Kubernetes Cluster.
// obj must be a struct pointer so that obj can be updated with the response
// returned by the Server.
Get(ctx context.Context, key ObjectKey, obj runtime.Object) error
// List retrieves list of objects for a given namespace and list options. On a
// successful call, Items field in the list will be populated with the
// result returned from the server.
List(ctx context.Context, list runtime.Object, opts ...ListOptionFunc) error
}
// Writer knows how to create, delete, and update Kubernetes objects.
type Writer interface {
// Create saves the object obj in the Kubernetes cluster.
Create(ctx context.Context, obj runtime.Object, opts ...CreateOptionFunc) error
// Delete deletes the given obj from Kubernetes cluster.
Delete(ctx context.Context, obj runtime.Object, opts ...DeleteOptionFunc) error
// Update updates the given obj in the Kubernetes cluster. obj must be a
// struct pointer so that obj can be updated with the content returned by the Server.
Update(ctx context.Context, obj runtime.Object, opts ...UpdateOptionFunc) error
// Patch patches the given obj in the Kubernetes cluster. obj must be a
// struct pointer so that obj can be updated with the content returned by the Server.
Patch(ctx context.Context, obj runtime.Object, patch Patch, opts ...PatchOptionFunc) error
}
// StatusClient knows how to create a client which can update status subresource
// for kubernetes objects.
type StatusClient interface {
Status() StatusWriter
}感謝你能夠認(rèn)真閱讀完這篇文章，希望小編分享的“kubernetes CRD開發(fā)的示例分析”這篇文章對大家有幫助，同時(shí)也希望大家多多支持創(chuàng)新互聯(lián)，關(guān)注創(chuàng)新互聯(lián)行業(yè)資訊頻道，更多相關(guān)知識等著你來學(xué)習(xí)!