在前面的文章当中我们已经完成了 NodePool Operator 的基本功能开发与测试，但是有时候我们会有这种需求，例如创建或者删除资源的时候需要对资源进行一些检查的操作，如果校验不成功就不通过。或者是需要在完成实际的创建之前做一些其他操作，例如我创建一个 pod 之前对 pod 的资源做一些调整等。这些都可以通过准入控制的WebHook来实现。
准入控制存在两种 WebHook，变更准入控制 MutatingAdmissionWebhook，和验证准入控制 ValidatingAdmissionWebhook，执行的顺序是先执行 MutatingAdmissionWebhook 再执行 ValidatingAdmissionWebhook。
创建 webhook
我们通过命令创建相关的脚手架代码和 api
- kubebuilder create webhook --group nodes --version v1 --kind NodePool --defaulting --programmatic-validation
执行之后可以看到多了一些 webhook 相关的文件和配置
- ├── api
- │ └── v1
- │ ├── groupversion_info.go
- │ ├── nodepool_types.go
- + │ ├── nodepool_webhook.go # 在这里实现 webhook 的相关接口
- + │ ├── webhook_suite_test.go # webhook 测试
- │ └── zz_generated.deepcopy.go
- ├── bin
- ├── config
- + │ ├── certmanager # 用于部署
- │ ├── crd
- │ │ ├── bases
- │ │ │ └── nodes.lailin.xyz_nodepools.yaml
- │ │ ├── kustomization.yaml
- │ │ ├── kustomizeconfig.yaml
- │ │ └── patches
- │ │ ├── cainjection_in_nodepools.yaml
- + │ │ └── webhook_in_nodepools.yaml
- │ ├── default
- │ │ ├── kustomization.yaml
- │ │ ├── manager_auth_proxy_patch.yaml
- │ │ ├── manager_config_patch.yaml
- + │ │ ├── manager_webhook_patch.yaml
- + │ │ └── webhookcainjection_patch.yaml
- │ ├── manager
- │ ├── prometheus
- │ ├── rbac
- │ ├── samples
- │ │ └── nodes_v1_nodepool.yaml
- + │ └── webhook # webhook 部署配置
- ├── controllers
- ├── main.go
实现逻辑
实现 MutatingAdmissionWebhook 接口
这个只需要实现 Default 方法就行
- // Default implements webhook.Defaulter so a webhook will be registered for the type
- func (r *NodePool) Default() {
- nodepoollog.Info("default", "name", r.Name)
- // 如果 labels 为空，我们就给 labels 加一个默认值
- if len(r.Labels) == 0 {
- r.Labels["node-pool.lailin.xyz"] = r.Name
- }
- }
实现 ValidatingAdmissionWebhook 接口
实现 ValidatingAdmissionWebhook也是一样只需要实现对应的方法就行了，默认是注册了 Create 和 Update 事件的校验，我们这里主要是限制 Labels 和 Taints 的 key 只能是满足正则 ^node-pool.lailin.xyz/*[a-zA-z0-9]*$ 的固定格式
- // TODO(user): change verbs to "verbs=create;update;delete" if you want to enable deletion validation.
- //+kubebuilder:webhook:path=/validate-nodes-lailin-xyz-v1-nodepool,mutating=false,failurePolicy=fail,sideEffects=None,groups=nodes.lailin.xyz,resources=nodepools,verbs=create;update,versions=v1,name=vnodepool.kb.io,admissionReviewVersions={v1,v1beta1}
- var _ webhook.Validator = &NodePool{}
- // ValidateCreate implements webhook.Validator so a webhook will be registered for the type
- func (r *NodePool) ValidateCreate() error {
- nodePoolLog.Info("validate create", "name", r.Name)
- return r.validate()
- }
- // ValidateUpdate implements webhook.Validator so a webhook will be registered for the type
- func (r *NodePool) ValidateUpdate(old runtime.Object) error {
- nodePoolLog.Info("validate update", "name", r.Name)
- return r.validate()
- }
- // ValidateDelete implements webhook.Validator so a webhook will be registered for the type
- func (r *NodePool) ValidateDelete() error {
- nodePoolLog.Info("validate delete", "name", r.Name)
- // TODO(user): fill in your validation logic upon object deletion.
- return nil
- }
- // validate 验证
- func (r *NodePool) validate() error {
- err := errors.Errorf("taint or label key must validatedy by %s", keyReg.String())
- for k := range r.Spec.Labels {
- if !keyReg.MatchString(k) {
- return errors.WithMessagef(err, "label key: %s", k)
- }
- }
- for _, taint := range r.Spec.Taints {
- if !keyReg.MatchString(taint.Key) {
- return errors.WithMessagef(err, "taint key: %s", taint.Key)
- }
- }
- return nil
- }
部署
实现了之后直接在 make run 是跑不起来的，因为 webhook 注册的地址不对，我们这里先看一下如何进行部署运行，然后再来看如何对 WebHook 进行本地调试。
WebHook 的运行需要校验证书，kubebuilder 官方建议我们使用 cert-manager 简化对证书的管理，所以我们先部署一下 cert-manager 的服务
- kubectl apply -f https://github.com/jetstack/cert-manager/releases/download/v1.3.1/cert-manager.yaml
然后我们 build 镜像并且将镜像 load 到集群中
- make docker-build
- kind load docker-image --name kind --nodes kind-worker controller:latest
然后查看一下 config/default/kustomization.yaml文件，确认 webhook 相关的配置没有被注释掉
- # Adds namespace to all resources.
- namespace: node-pool-operator-system
- # Value of this field is prepended to the
- # names of all resources, e.g. a deployment named
- # "wordpress" becomes "alices-wordpress".
- # Note that it should also match with the prefix (text before '-') of the namespace
- # field above.
- namePrefix: node-pool-operator-
- # Labels to add to all resources and selectors.
- #commonLabels:
- # someName: someValue
- bases:
- - ../crd
- - ../rbac
- - ../manager
- # [WEBHOOK] To enable webhook, uncomment all the sections with [WEBHOOK] prefix including the one in
- # crd/kustomization.yaml
- - ../webhook
- # [CERTMANAGER] To enable cert-manager, uncomment all sections with 'CERTMANAGER'. 'WEBHOOK' components are required.
- - ../certmanager
- # [PROMETHEUS] To enable prometheus monitor, uncomment all sections with 'PROMETHEUS'.
- #- ../prometheus
- patchesStrategicMerge:
- # Protect the /metrics endpoint by putting it behind auth.
- # If you want your controller-manager to expose the /metrics
- # endpoint w/o any authn/z, please comment the following line.
- - manager_auth_proxy_patch.yaml
- # Mount the controller config file for loading manager configurations
- # through a ComponentConfig type
- #- manager_config_patch.yaml
- # [WEBHOOK] To enable webhook, uncomment all the sections with [WEBHOOK] prefix including the one in
- # crd/kustomization.yaml
- - manager_webhook_patch.yaml
- # [CERTMANAGER] To enable cert-manager, uncomment all sections with 'CERTMANAGER'.
- # Uncomment 'CERTMANAGER' sections in crd/kustomization.yaml to enable the CA injection in the admission webhooks.
- # 'CERTMANAGER' needs to be enabled to use ca injection
- - webhookcainjection_patch.yaml
- # the following config is for teaching kustomize how to do var substitution
- vars:
- # [CERTMANAGER] To enable cert-manager, uncomment all sections with 'CERTMANAGER' prefix.
- - name: CERTIFICATE_NAMESPACE # namespace of the certificate CR
- objref:
- kind: Certificate
- group: cert-manager.io
- version: v1
- name: serving-cert # this name should match the one in certificate.yaml
- fieldref:
- fieldpath: metadata.namespace
- - name: CERTIFICATE_NAME
- objref:
- kind: Certificate
- group: cert-manager.io
- version: v1
- name: serving-cert # this name should match the one in certificate.yaml
- - name: SERVICE_NAMESPACE # namespace of the service
- objref:
- kind: Service
- version: v1
- name: webhook-service
- fieldref:
- fieldpath: metadata.namespace
- - name: SERVICE_NAME
- objref:
- kind: Service
- version: v1
- name: webhook-service
检查一下 manager/manager.yaml 是否存在 imagePullPolicy: IfNotPresent不存在要加上
然后执行部署命令即可
- make deploy
- # 检查 pod 是否正常启动
- ▶ kubectl -n node-pool-operator-system get pods
- NAME READY STATUS RESTARTS AGE
- node-pool-operator-controller-manager-66bd747899-lf7xb 0/2 ContainerCreating 0 7s
使用 yaml 文件测试一下
- apiVersion: nodes.lailin.xyz/v1
- kind: NodePool
- metadata:
- name: worker
- spec:
- labels:
- "xxx": "10"
- handler: runc
提交之后可以发现报错，因为 label key 不满足我们的要求
- ▶ kubectl apply -f config/samples/
- Error from server (label key: xxx: taint or label key must validatedy by ^node-pool.lailin.xyz/*[a-zA-z0-9]*$): error when applying patch:
- {"metadata":{"annotations":{"kubectl.kubernetes.io/last-applied-configuration":"{\"apiVersion\":\"nodes.lailin.xyz/v1\",\"kind\":\"NodePool\",\"metadata\":{\"annotations\":{},\"name\":\"worker\"},\"spec\":{\"handler\":\"runc\",\"labels\":{\"xxx\":\"10\"}}}\n"}},"spec":{"labels":{"node-pool.lailin.xyz/worker":null,"xxx":"10"},"taints":null}}
- to:
- Resource: "nodes.lailin.xyz/v1, Resource=nodepools", GroupVersionKind: "nodes.lailin.xyz/v1, Kind=NodePool"
- Name: "worker", Namespace: ""
- for: "config/samples/nodes_v1_nodepool.yaml": admission webhook "vnodepool.kb.io" denied the request: label key: xxx: taint or label key must validatedy by ^node-pool.lailin.xyz/*[a-zA-z0-9]*$
再用一个正常的 yaml 测试
- apiVersion: nodes.lailin.xyz/v1
- kind: NodePool
- metadata:
- name: worker
- spec:
- labels:
- "node-pool.lailin.xyz/xxx": "10"
- handler: runc
可以正常提交
- ▶ kubectl apply -f config/samples/
- nodepool.nodes.lailin.xyz/worker configured
本地调试
虽然 kubebuilder 已经为我们做了很多事情将服务部署运行基本傻瓜化了，但是每次做一点点修改就需要重新编译部署还是非常的麻烦，所以我们来看看如何在本地进行联调。
- PS: 这里会用到之前 4. kustomize 简明教程 讲到的 kustomize 的特性构建开发环境，如果忘记了可以先看看之前的文章哦
我们先看看 config/webhook/manifests.yaml这里面包含了两个准入控制的信息，不过他们的配置类似，我们看一个就行了，这里以 MutatingWebhookConfiguration 为例
- apiVersion: admissionregistration.k8s.io/v1
- kind: MutatingWebhookConfiguration
- metadata:
- creationTimestamp: null
- name: mutating-webhook-configuration
- webhooks:
- - admissionReviewVersions:
- - v1
- - v1beta1
- clientConfig:
- service:
- name: webhook-service
- namespace: system
- path: /mutate-nodes-lailin-xyz-v1-nodepool
- failurePolicy: Fail
- name: mnodepool.kb.io
- rules:
- - apiGroups:
- - nodes.lailin.xyz
- apiVersions:
- - v1
- operations:
- - CREATE
- - UPDATE
- resources:
- - nodepools
- sideEffects: None
主要是 clientConfig 的配置，如果想要本地联调，我们需要将 clientConfig.service 删掉，替换成
- clientConfig:
- url: https://host.docker.internal:9443/mutate-nodes-lailin-xyz-v1-nodepool
注意: host.docker.internal是 docker desktop 的默认域名，通过这个可以调用到宿主机上的服务，url path mutate-nodes-lailin-xyz-v1-nodepool需要和 service 中的 path 保持一致
然后再加上 caBundle
- clientConfig:
- caBundle: CA证书 base64 后的字符串
证书
想要本地联调需要先生成证书，我们使用 openssl 来生成，先创建一个 config/cert 文件夹，我们把证书都放到这里
首先创建一个 csr.conf文件
- [ req ]
- default_bits = 2048
- prompt = no
- default_md = sha256
- req_extensions = req_ext
- distinguished_name = dn
- [ dn ]
- C = CN
- ST = Guangzhou
- L = Shenzhen
- CN = host.docker.internal
- [ req_ext ]
- subjectAltName = @alt_names
- [ alt_names ]
- DNS.1 = host.docker.internal # 这里由于我们直接访问的是域名所以用 DNS
- [ v3_ext ]
- authorityKeyIdentifier=keyid,issuer:always
- basicConstraints=CA:FALSE
- keyUsage=keyEncipherment,dataEncipherment
- extendedKeyUsage=serverAuth,clientAuth
- subjectAltName=@alt_names
然后生成 CA 证书并且签发本地证书
- # 生成 CA 证书
- openssl genrsa -out ca.key 2048
- openssl req -x509 -new -nodes -key ca.key -subj "/CN=host.docker.internal" -days 10000 -out ca.crt
- # 签发本地证书
- openssl genrsa -out tls.key 2048
- openssl req -new -SHA256 -newkey rsa:2048 -nodes -keyout tls.key -out tls.csr -subj "/C=CN/ST=Shanghai/L=Shanghai/O=/OU=/CN=host.docker.internal"
- openssl req -new -key tls.key -out tls.csr -config csr.conf
- openssl x509 -req -in tls.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out tls.crt -days 10000 -extensions v3_ext -extfile csr.conf
配置变更
我们为了和原本的开发体验保持一致，所以利用 kustomize 的特性新建一个 config/dev 文件夹，包含两个文件修改我们想要的配置
- ▶ tree config/dev
- config/dev
- ├── kustomization.yaml
- └── webhook_patch.yaml
先看一下 kustomization.yaml，从 default 文件夹中继承配置，然后使用 patches 修改一些配置，主要是分别给两种准入控制 WebHook 添加 url 字段，然后使用 webhook_patch.yaml对两个文件做些统一的配置
- resources:
- - ../default
- patches:
- - patch: |
- - op: "add"
- path: "/webhooks/0/clientConfig/url"
- value: "https://host.docker.internal:9443/mutate-nodes-lailin-xyz-v1-nodepool"
- target:
- kind: MutatingWebhookConfiguration
- - patch: |
- - op: "add"
- path: "/webhooks/0/clientConfig/url"
- value: "https://host.docker.internal:9443/validate-nodes-lailin-xyz-v1-nodepool"
- target:
- kind: ValidatingWebhookConfiguration
- - path: webhook_patch.yaml
- target:
- group: admissionregistration.k8s.io
webhook_patch.yaml 这个主要是移除 cert-manager.io 的 annotation，本地调试不需要使用它进行证书注入，然后移除掉 service 并且添加 CA 证书
- - op: "remove"
- path: "/metadata/annotations/cert-manager.io~1inject-ca-from"
- - op: "remove"
- path: "/webhooks/0/clientConfig/service"
- - op: "add"
- path: "/webhooks/0/clientConfig/caBundle"
- value: CA 证书 base64 后的值
CA 证书的值可以通过以下命令获取
- cat config/cert/ca.crt | base64 | tr -d '\n'
然后修改一下 main.go将证书文件夹指定到我们刚刚生成好的文件目录
- mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
- Scheme: scheme,
- MetricsBindAddress: metricsAddr,
- Port: 9443,
- HealthProbeBindAddress: probeAddr,
- LeaderElection: enableLeaderElection,
- LeaderElectionID: "97acaccf.lailin.xyz",
- + CertDir: "config/cert/", // 手动指定证书位置用于测试
- })
为了方便调试，在 makefile 中添加
- dev: manifests kustomize
- cd config/manager && $(KUSTOMIZE) edit set image controller=${IMG}
- $(KUSTOMIZE) build config/dev | kubectl apply -f -
最后执行一下 make dev 然后再执行 make run 就行了
总结
今天完成了准入控制 WebHook 的实现，虽然这个例子可能不太好，如果只需要校验正则，直接配置一下//+kubebuilder:validation:Pattern=string就行了，但是学习了这个之后其实可以做很多事情，例如给 pod 增加 sidecar 根据应用类型的不同注入不同的一些 agent 等等.
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