Hedon

# Ingress

我们已经知道，Service 对集群之外暴露服务的主要方式有两种：

  • NodePort
  • LoadBalancer

但是这两种方式，都有一定的缺点：

  • NodePort方式 的缺点是会占用很多集群机器的端口，那么当集群服务变多的时候，这个缺点就愈发明显
  • LoadBalancer 的缺点是每个 Service 都需要一个 LB，浪费，麻烦，并且需要 k8s 之外的设备的支持

基于这种现状，k8s 提供了 Ingress 资源对象，Ingress 只需要一个 NodePort 或者一个 LB 就可以满足暴露多个 Service 的需求，工作机制大致如下图所示：

# 一、Ingress 原理

Ingress介绍.png

实际上，Ingress 相当于一个七层的负载均衡器，是 k8s 对反向代理的一个抽象，它的工作原理类似于 Nginx，可以理解为 Ingress 里面建立了诸多映射规则，Ingress Controller 通过监听这些配置规则并转化为 Nginx 的反向代理配置，然后对外提供服务。

  • Ingress：k8s 中的一个对象，作用是定义请求如何转发到 Service 的规则
  • Ingress Controller：具体实现反向代理及负载均衡的程序，对 Ingress 定义的规则进行解析，根据配置的规则来实现请求转发，实现的方式有很多，比如 Nginx，Contour，Haproxy 等

Ingress（以Nginx）的工作原理如下：

  1. 用户编写 Ingress 规则，说明那个域名对应 k8s 集群中的哪个 Service；
  2. Ingress Controller 动态感知 Ingress 服务规则的变化，然后生成一段对应的 Nginx 的反向代理配置；
  3. Ingress Controller 会将生成的 Nginx 配置写入到一个运行着的 Nginx 服务中，并动态更新；
  4. 到此为止，其实真正在工作的就是一个 Nginx 了，内部配置了用户定义的请求规则。

image-20210709104809548

# 二、Ingress 使用

# 1. 环境准备

# 1.1 搭建 Ingress 环境

  • 创建 ingress 文件夹，并进去其中

    [root@k8s-master k8s]# mkdir ingress
[root@k8s-master k8s]# cd ingress/
[root@k8s-master ingress]#

  • 获取 ingress-nginx（v0.30.0）

    wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/mandatory.yaml

    wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/provider/baremetal/service-nodeport.yaml

    其实就是两个 yaml 文件，下载不了的话可以直接复制下面内容：

    mandatory.yaml

    apiVersion: v1
kind: Namespace
metadata:
  name: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---

kind: ConfigMap
apiVersion: v1
metadata:
  name: nginx-configuration
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
kind: ConfigMap
apiVersion: v1
metadata:
  name: tcp-services
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
kind: ConfigMap
apiVersion: v1
metadata:
  name: udp-services
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: nginx-ingress-serviceaccount
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
  name: nginx-ingress-clusterrole
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
rules:
  - apiGroups:
      - ""
    resources:
      - configmaps
      - endpoints
      - nodes
      - pods
      - secrets
    verbs:
      - list
      - watch
  - apiGroups:
      - ""
    resources:
      - nodes
    verbs:
      - get
  - apiGroups:
      - ""
    resources:
      - services
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - ""
    resources:
      - events
    verbs:
      - create
      - patch
  - apiGroups:
      - "extensions"
      - "networking.k8s.io"
    resources:
      - ingresses
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - "extensions"
      - "networking.k8s.io"
    resources:
      - ingresses/status
    verbs:
      - update

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: Role
metadata:
  name: nginx-ingress-role
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
rules:
  - apiGroups:
      - ""
    resources:
      - configmaps
      - pods
      - secrets
      - namespaces
    verbs:
      - get
  - apiGroups:
      - ""
    resources:
      - configmaps
    resourceNames:
      # Defaults to "<election-id>-<ingress-class>"
      # Here: "<ingress-controller-leader>-<nginx>"
      # This has to be adapted if you change either parameter
      # when launching the nginx-ingress-controller.
      - "ingress-controller-leader-nginx"
    verbs:
      - get
      - update
  - apiGroups:
      - ""
    resources:
      - configmaps
    verbs:
      - create
  - apiGroups:
      - ""
    resources:
      - endpoints
    verbs:
      - get

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
metadata:
  name: nginx-ingress-role-nisa-binding
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: nginx-ingress-role
subjects:
  - kind: ServiceAccount
    name: nginx-ingress-serviceaccount
    namespace: ingress-nginx

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: nginx-ingress-clusterrole-nisa-binding
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: nginx-ingress-clusterrole
subjects:
  - kind: ServiceAccount
    name: nginx-ingress-serviceaccount
    namespace: ingress-nginx

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-ingress-controller
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: ingress-nginx
      app.kubernetes.io/part-of: ingress-nginx
  template:
    metadata:
      labels:
        app.kubernetes.io/name: ingress-nginx
        app.kubernetes.io/part-of: ingress-nginx
      annotations:
        prometheus.io/port: "10254"
        prometheus.io/scrape: "true"
    spec:
      # wait up to five minutes for the drain of connections
      terminationGracePeriodSeconds: 300
      serviceAccountName: nginx-ingress-serviceaccount
      nodeSelector:
        kubernetes.io/os: linux
      containers:
        - name: nginx-ingress-controller
          image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.30.0
          args:
            - /nginx-ingress-controller
            - --configmap=$(POD_NAMESPACE)/nginx-configuration
            - --tcp-services-configmap=$(POD_NAMESPACE)/tcp-services
            - --udp-services-configmap=$(POD_NAMESPACE)/udp-services
            - --publish-service=$(POD_NAMESPACE)/ingress-nginx
            - --annotations-prefix=nginx.ingress.kubernetes.io
          securityContext:
            allowPrivilegeEscalation: true
            capabilities:
              drop:
                - ALL
              add:
                - NET_BIND_SERVICE
            # www-data -> 101
            runAsUser: 101
          env:
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
            - name: POD_NAMESPACE
              valueFrom:
                fieldRef:
                  fieldPath: metadata.namespace
          ports:
            - name: http
              containerPort: 80
              protocol: TCP
            - name: https
              containerPort: 443
              protocol: TCP
          livenessProbe:
            failureThreshold: 3
            httpGet:
              path: /healthz
              port: 10254
              scheme: HTTP
            initialDelaySeconds: 10
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 10
          readinessProbe:
            failureThreshold: 3
            httpGet:
              path: /healthz
              port: 10254
              scheme: HTTP
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 10
          lifecycle:
            preStop:
              exec:
                command:
                  - /wait-shutdown

---

apiVersion: v1
kind: LimitRange
metadata:
  name: ingress-nginx
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  limits:
  - min:
      memory: 90Mi
      cpu: 100m
    type: Container

    service-nodeport.yaml

    apiVersion: v1
kind: Service
metadata:
  name: ingress-nginx
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  type: NodePort
  ports:
    - name: http
      port: 80
      targetPort: 80
      protocol: TCP
    - name: https
      port: 443
      targetPort: 443
      protocol: TCP
  selector:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---

  • 创建 ingress-nginx

    [root@k8s-master ingress]# kubectl apply -f ./
namespace/ingress-nginx created
configmap/nginx-configuration created
configmap/tcp-services created
configmap/udp-services created
serviceaccount/nginx-ingress-serviceaccount created
clusterrole.rbac.authorization.k8s.io/nginx-ingress-clusterrole created
role.rbac.authorization.k8s.io/nginx-ingress-role created
rolebinding.rbac.authorization.k8s.io/nginx-ingress-role-nisa-binding created
clusterrolebinding.rbac.authorization.k8s.io/nginx-ingress-clusterrole-nisa-binding created
deployment.apps/nginx-ingress-controller created
limitrange/ingress-nginx created
service/ingress-nginx created

  • 查看 ingress-nginx

    service/ingress-nginx created
[root@k8s-master ingress]# kubectl get pod -n ingress-nginx
NAME                                        READY   STATUS    RESTARTS   AGE
nginx-ingress-controller-5bb8fb4bb6-zbb8x   1/1     Running   0          30s

  • 查看 Service

    [root@k8s-master ingress]# kubectl get svc -n ingress-nginx
NAME            TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
ingress-nginx   NodePort   10.109.184.192   <none>        80:32235/TCP,443:31935/TCP   64s

# 1.2 准备 Pod 和 Service

  • 为了后面的实验比较方便，创建如下图所示的模型：

    image-20210709105648149

  • 创建 tomcat-nginx.yaml 文件，内容如下：

    apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: dev
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1
        ports:
        - containerPort: 80

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-deployment
  namespace: dev
spec:
  replicas: 3
  selector:
    matchLabels:
      app: tomcat-pod
  template:
    metadata:
      labels:
        app: tomcat-pod
    spec:
      containers:
      - name: tomcat
        image: tomcat:8.5-jre10-slim
        ports:
        - containerPort: 8080

---

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  namespace: dev
spec:
  selector:
    app: nginx-pod
  clusterIP: None
  type: ClusterIP
  ports:
  - port: 80
    targetPort: 80

---

apiVersion: v1
kind: Service
metadata:
  name: tomcat-service
  namespace: dev
spec:
  selector:
    app: tomcat-pod
  clusterIP: None
  type: ClusterIP
  ports:
  - port: 8080
    targetPort: 8080

  • 清理环境

    [root@k8s-master ingress]# kubectl delete ns dev
namespace "dev" deleted
[root@k8s-master ingress]# kubectl create ns dev
namespace/dev created

  • 创建 Pod 和 Service

    [root@k8s-master ingress]# kubectl apply -f tomcat-nginx.yaml 
deployment.apps/nginx-deployment created
deployment.apps/tomcat-deployment created
service/nginx-service created
service/tomcat-service created

  • 查看 Pod 和 Service

    [root@k8s-master ingress]# kubectl get pod,service -n dev
NAME                                     READY   STATUS    RESTARTS   AGE
pod/nginx-deployment-7d7dd5499b-bt96d    1/1     Running   0          69s
pod/nginx-deployment-7d7dd5499b-bwsnp    1/1     Running   0          69s
pod/nginx-deployment-7d7dd5499b-pbvzs    1/1     Running   0          69s
pod/tomcat-deployment-7d5fcd4756-4j2sv   1/1     Running   0          69s
pod/tomcat-deployment-7d5fcd4756-dv5n8   1/1     Running   0          69s
pod/tomcat-deployment-7d5fcd4756-lpqbk   1/1     Running   0          69s

NAME                     TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE
service/nginx-service    ClusterIP   None         <none>        80/TCP     69s
service/tomcat-service   ClusterIP   None         <none>        8080/TCP   69s

# 2. HTTP 代理

  • 创建 ingress-http.yaml 文件

    apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-http
  namespace: dev
spec:
  rules:
    - host: nginx.hedon.com #可以通过这个域名来访问我们的Nginx
      http:
        paths:
          - path: /
            backend:
              serviceName: nginx-service
              servicePort: 80
    - host: tomcat.hedon.com #可以通过这个域名来访问我们的Tomcat
      http:
        paths:
          - path: /
            backend:
              serviceName: tomcat-service
              servicePort: 8080

    image-20210709110948793

  • 创建 ingress-http

    [root@k8s-master ingress]# kubectl create -f ingress-http.yaml
ingress.extensions/ingress-http created

  • 查看 ingress

    [root@k8s-master ingress]# kubectl get ingress ingress-http -n dev
NAME           CLASS    HOSTS                              ADDRESS          PORTS   AGE
ingress-http   <none>   nginx.hedon.com,tomcat.hedon.com   10.109.184.192   80      4m33s

  • 查看对应的 Service

    [root@k8s-master ingress]# kubectl get service -n ingress-nginx
NAME            TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
ingress-nginx   NodePort   10.109.184.192   <none>        80:32235/TCP,443:31935/TCP   21m

  • 在宿主机的 /etc/hosts 文件中添加如下映射：(172.16.58.200 为 Master 节点的 IP 地址)

    172.16.58.200 nginx.hedon.com
172.16.58.200 tomcat.hedon.com

  • 查看端口

    [root@k8s-master ingress]# kubectl get service -n ingress-nginx
NAME            TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
ingress-nginx   NodePort   10.109.184.192   <none>        80:32235/TCP,443:31935/TCP   27m

  • 访问

    http://nginx.hedon.com:32235
http://tomcat.hedon.com:32235

# 3. HTTPS 代理

  • 生成证书

    openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/C=CN/ST=BJ/L=BJ/O=nginx/CN=hedon.com"

  • 创建密钥

    kubectl create secret tls tls-secret --key tls.key --cert tls.crt

  • 创建 ingress-https.yaml

    apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-https
  namespace: dev
spec:
  tls:
    - hosts:
      - nginx.hedon.com
      - tomcat.hedon.com
      secretName: tls-secret # 指定秘钥
  rules:
  - host: nginx.hedon.com
    http:
      paths:
      - path: /
        backend:
          serviceName: nginx-service
          servicePort: 80
  - host: tomcat.hedon.com
    http:
      paths:
      - path: /
        backend:
          serviceName: tomcat-service
          servicePort: 8080

  • 创建 ingress

    [root@k8s-master ingress]# kubectl create -f ingress-https.yaml
ingress.extensions/ingress-https created

  • 查看端口号

    [root@k8s-master ingress]# kubectl get service -n ingress-nginx
NAME            TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)                      AGE
ingress-nginx   NodePort   10.109.184.192   <none>        80:32235/TCP,443:31935/TCP   46m

  • 访问

    https://nginx.hedon.com:31935
https://tomcat.hedon.com:31935
上次更新: 7/9/2021, 12:00:10 PM

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