博客原文

文章目录

• • k8s 集群配置
  • 介绍
  • Admission Webhook
  • WebHook 入门实践: github 认证接入
  • • web 服务器
    • Dockerfile 镜像制作
    • • amd64
      • x86_64
      • 构造镜像
      • 检验镜像
      • Makefile
      • webhook 接入 apiserver
      • • webhook.yaml
        • apiserver 挂载 webconfig
        • 在 github 中创建认证 token
        • 将 token 添加到 kubeconfig
        • 验证
        • • 授权验证
          • deploy spec
          • 参考

            k8s 集群配置

            IP	Host	配置
            11.0.1.150	master1 (keepalived+haproxy)	2C 4G 30G
            11.0.1.151	master2 (keepalived+haproxy)	2C 4G 30G
            11.0.1.152	node1	2C 4G 30G

            vip 地址: https://11.0.1.100:16443

            介绍

            Webhook就是一种HTTP回调，用于在某种情况下执行某些动作，Webhook不是K8S独有的，很多场景下都可以进行Webhook，比如在提交完代码后调用一个Webhook自动构建docker镜像

            K8S中提供了自定义资源类型和自定义控制器来扩展功能，还提供了动态准入控制，其实就是通过Webhook来实现准入控制，分为两种：验证性质的准入 Webhook （Validating Admission Webhook） 和 修改性质的准入 Webhook （Mutating Admission Webhook）

            Admission Webhook有哪些使用场景？如下

            • 在资源持久化到ETCD之前进行修改（Mutating Webhook），比如增加init Container或者sidecar Container
            • 在资源持久化到ETCD之前进行校验（Validating Webhook），不满足条件的资源直接拒绝并给出相应信息

              现在非常火热的的 Service Mesh 应用istio就是通过 mutating webhooks 来自动将Envoy这个 sidecar 容器注入到 Pod 中去的：

              https://istio.io/docs/setup/kubernetes/sidecar-injection/。

              更多详情介绍可参考：

              https://kubernetes.io/zh/docs/reference/access-authn-authz/extensible-admission-controllers/

              Admission Webhook

              上面提到K8S的动态准入控制是通过Webhook来实现的，那么它到底是在哪个环节执行的？请看下图

              

              综上, k8s webhook 可分为两类:

              1. Mutating Webhook: 这类 webhook 可以更改请求对象
              2. Validating Webhook: 这类 webhook 不能去更改请求对象, 就算更改也会被忽略, 用于写入 etcd 前的验证逻辑

              WebHook 入门实践: github 认证接入

              源码地址: https://github.com/Ai-feier/k8s-webhook/tree/main/auth-github

              写一个用于认证校验的 mutating webhook

              请求流程:

              1. 拦截 apiserver 请求
              2. 将请求(TokenReview)中的 token 发送给 github 用于验证
              3. 将 github 返回的用户信息填入 TokenReview

              web 服务器

              package main
              import (
              	"context"
              	"encoding/json"
              	"github.com/google/go-github/github"
              	"golang.org/x/oauth2"
              	authentication "k8s.io/api/authentication/v1beta1"
              	"log"
              	"net/http"
              )
              func main() {
              	http.HandleFunc("/authenticate", func(writer http.ResponseWriter, request *http.Request) {
              		// 获取请求中的 TokonReview
              		decoder := json.NewDecoder(request.Body)
              		var tokenReview authentication.TokenReview
              		if err := decoder.Decode(&tokenReview); err != nil {
              			log.Println("decode error: ", err)
              			// 响应返回错误
              			writer.WriteHeader(http.StatusBadRequest)
              			_ = json.NewEncoder(writer).Encode(map[string]interface{}{
              				"apiVersion": "authentication.k8s.io/v1beta1",
              				"kind":       "TokenReview",
              				"status": authentication.TokenReviewStatus{
              					Authenticated: false,
              				},
              			})
              			return
              		}
              		log.Println("receive request")
              		// 检查用户
              		// 创建 oauth2 对象, 发送给 github
              		oauthToken := oauth2.StaticTokenSource(&oauth2.Token{
              			AccessToken: tokenReview.Spec.Token, // tokenReview 的 token
              		})
              		oauthClient := oauth2.NewClient(context.Background(), oauthToken)
              		client := github.NewClient(oauthClient)
              		user, _, err := client.Users.Get(context.Background(), "")
              		if err != nil {
              			log.Println("github auth error: ", err)
              			writer.WriteHeader(http.StatusUnauthorized)
              			_ = json.NewEncoder(writer).Encode(map[string]any{
              				"apiVersion": "authentication.k8s.io/v1beta1",
              				"kind":       "TokenReview",
              				"status": authentication.TokenReviewStatus{
              					Authenticated: false, // 返回认证失败
              				},
              			})
              			return
              		}
              		// 认证成功
              		log.Println("github login success, as: ", *user.Login)
              		status := authentication.TokenReviewStatus{
              			Authenticated: true,
              			User: authentication.UserInfo{
              				Username: *user.Login,
              				UID: *user.Login,
              			},
              		}
              		json.NewEncoder(writer).Encode(map[string]any{
              			"apiVersion": "authentication.k8s.io/v1beta1",
              			"kind":       "TokenReview",
              			"status": status,
              		})
              	})
              	log.Println(http.ListenAndServe(":3000", nil))
              }
              

              Dockerfile 镜像制作

              本项目是使用 go 作为 web 服务器, go 提供一种非常好用的编译特性 – 交叉编译

              在 dockerfile 中我们选择的 busybox 作为基础镜像, 但默认 busybox 架构为 x86_64(uname -m查看), 所以可以使用 amd64/busybox 或交叉编译 go 代码

              当出现这类问题 exec /usr/bin/sh: exec format error 多半是架构问题

              推荐: Golang交叉编译详解 – CSDN

              amd64

              FROM golang:1.20 as builder
              WORKDIR /app
              COPY . .
              # go 交叉编译: amd64
              RUN go env -w  GOPROXY=https://goproxy.cn,direct && go mod tidy && \
                  CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o main main.go 
              RUN chmod +x /app/main
              FROM amd64/busybox
              COPY --from=builder /app/main .
              EXPOSE 3000/tcp
              CMD ["/main"]
              

              x86_64

              FROM golang:1.20 as builder
              WORKDIR /app
              COPY . .
              # go 交叉编译: x86
              RUN go env -w  GOPROXY=https://goproxy.cn,direct && go mod tidy && \
                  CGO_ENABLED=0 GOOS=linux GOARCH=386 go build -o main main.go 
              RUN chmod +x /app/main
              FROM busybox
              COPY --from=builder /app/main .
              EXPOSE 3000/tcp
              CMD ["/main"]
              

              构造镜像

              $ docker build -t aifeierwithinmkt/auth-github-webhook:amd64 -f Dockerfile_amd64 .
              $ docker build -t aifeierwithinmkt/auth-github-webhook:x86 -f Dockerfile_x86 .
              $ docker tag aifeierwithinmkt/auth-github-webhook:amd64 aifeierwithinmkt/auth-github-webhook
              

              检验镜像

              $ docker run --rm -p 3000:3000 -d aifeierwithinmkt/auth-github-webhook:amd64
              $ docker run --rm -p 3001:3000 -d aifeierwithinmkt/auth-github-webhook:x86
              $ curl 127.0.0.1:3000/authenticate
              {"apiVersion":"authentication.k8s.io/v1beta1","kind":"TokenReview","status":{"user":{}}}
              $ curl 127.0.0.1:3001/authenticate
              {"apiVersion":"authentication.k8s.io/v1beta1","kind":"TokenReview","status":{"user":{}}}
              

              镜像服务正常

              Makefile

              build_amd64:
              	mkdir -p bin/amd64
              	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o bin/amd64/main .
              build_x86:
              	mkdir -p bin/x86
              	CGO_ENABLED=0 GOOS=linux GOARCH=386 go build -o bin/x86/main .	
              

              webhook 接入 apiserver

              webhook.yaml

              apiVersion: v1
              clusters:
              - cluster:
                  server: http://192.168.1.7:3000/authenticate
                name: github-authn
              contexts:
              - context:
                  cluster: github-authn
                  user: authn-apiserver
                name: webhook
              current-context: webhook
              kind: Config
              preferences: {}
              users:
              - name: authn-apiserver
                user:
                  client-certificate-data: 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
                  client-key-data: 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
              

              该配置与 kubeconfig 配置相同, 直接在 kubeconfig 的基础上修改就行, 重要的是 cluster 的 server (即提供服务的地址

              apiserver 挂载 webconfig

              # 修改 apiserver 配置参数, 增加:
              - --authentication-token-webhook-config-file=/etc/config/webhook.yaml
              # 相应增加挂载卷
                  volumes:
                  - hostPath:
                      path: /etc/config
                      type: DirectoryOrCreate
                    name: auth-webhook
                  
                  volumeMounts:
                  - mountPath: /etc/config
                    name: auth-webhook
                    readOnly: true
              

              1. 修改 manifest 后 apiserver 理论上会自动重启, 如果没有则 systemctl restart kubelet
              2. 本文实验主题为认证 webhook 可直接使用 --authentication-token-webhook-config-file, 如需自定义 mutatingwebhook 请参考: mutatingwebhook

              在 github 中创建认证 token

              setting -> Developer Settings -> Personal access tokens (classic)

              将 token 添加到 kubeconfig

              # 在 kubeconfig 下增加一个 user
              - name: githubuser
                user:
                  token: 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
              

              验证

              $ k get po --user githubuser
              Error from server (Forbidden): pods is forbidden: User "Ai-feier" cannot list resource "pods" in API group "" in the namespace "default"
              

              授权验证

              $ k create clusterrolebinding testview --clusterrole view --user Ai-feier
              $ k get po --user githubuser
              NAME                         READY   STATUS    RESTARTS      AGE
              nginx-kusc00401              0/1     Pending   0             4d23h
              testnginx-5cdb847cd9-7nm4k   1/1     Running   1 (29h ago)   43h
              testnginx-5cdb847cd9-llmxf   1/1     Running   1 (29h ago)   43h
              testnginx-5cdb847cd9-qfsdn   1/1     Running   1 (29h ago)   43h
              web-server                   0/1     Pending   0             4d22h
              

              deploy spec

              apiVersion: apps/v1
              kind: Deployment
              metadata:
                labels:
                  app: auth-webhook
                name: auth-webhook
                namespace: default
              spec:
                replicas: 3
                selector:
                  matchLabels:
                    app: auth-webhook
                strategy: {}
                template:
                  metadata:
                    labels:
                      app: auth-webhook
                  spec:
                    containers:
                      - image: aifeierwithinmkt/auth-github-webhook
                        name: auth-github-webhook
                        resources: {}
                        ports:
                          - containerPort: 3000
              ---
              apiVersion: v1
              kind: Service
              metadata:
                name: auth-svc
                namespace: default
              spec:
                selector:
                  app: auth-webhook
                ports:
                  - name: auth
                    protocol: TCP
                    port: 80
                    targetPort: 3000
              

              参考

              1. https://kubernetes.io/zh-cn/docs/reference/access-authn-authz/extensible-admission-controllers/

               
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