写在前面

本文接k8s之ingress 。

本文看一个基于ingress作为流量入口的实战例子，架构图如下：

接下来详细看下。

1：部署MariaDB

首先我们需要定义MariaDB使用的configmap，如下：

apiVersion: v1
kind: ConfigMap
metadata:
  name: maria-cm

data:
  DATABASE: 'db'
  USER: 'wp'
  PASSWORD: '123'
  ROOT_PASSWORD: '123'

然后需要定义后MariaDB的deploy来维持MariaDB的POD数在一定个数，如下：

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: maria-dep
  name: maria-dep

spec:
  replicas: 1
  selector:
    matchLabels:
      app: maria-dep

  template:
    metadata:
      labels:
        app: maria-dep
    spec:
      containers:
      - image: mariadb:10
        name: mariadb
        ports:
        - containerPort: 3306

        envFrom:
        - prefix: 'MARIADB_'
          configMapRef:
            name: maria-cm

最后定义MariaDB的POD的service，这样可以域名方式访问POD，这样就不用关心POD的退出和新建而导致的IP地址变化问题，yaml如下：

apiVersion: v1
kind: Service
metadata:
  labels:
    app: maria-dep
  name: maria-svc

spec:
  ports:
  - port: 3306
    protocol: TCP
    targetPort: 3306
  selector:
    app: maria-dep

最后我们使用---将以上3个yaml定义在一个文件中，然后apply如下：

dongyunqi@mongodaddy:~/k8s$ kubectl apply -f wp-maria.yml 
configmap/maria-cm created
deployment.apps/maria-dep created
service/maria-svc created

查看如下：

dongyunqi@mongodaddy:~/k8s$ kubectl get pod
NAME                         READY   STATUS    RESTARTS   AGE
maria-dep-767bbdccb5-dbm2t   1/1     Running   0          41m
dongyunqi@mongodaddy:~/k8s$ kubectl get deployment
NAME        READY   UP-TO-DATE   AVAILABLE   AGE
maria-dep   1/1     1            1           41m
dongyunqi@mongodaddy:~/k8s$ kubectl get service
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
...
maria-svc    ClusterIP   10.108.87.240   <none>        3306/TCP   41m

2：部署WordPress

首先我们需要定义WordPress使用的ConfigMap，如下：

apiVersion: v1
kind: ConfigMap
metadata:
  name: wp-cm

data:
  HOST: 'maria-svc'
  USER: 'wp'
  PASSWORD: '123'
  NAME: 'db'

注意HOST: 'maria-svc'配置的是MariaDB的service 域名，这样就能屏蔽IP地址的变化带来的影响，然后定义deploy，控制WordPress的个数，这里定义2个POD，envFrom设置环境变量，如下：

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: wp-dep
  name: wp-dep

spec:
  replicas: 2
  selector:
    matchLabels:
      app: wp-dep

  template:
    metadata:
      labels:
        app: wp-dep
    spec:
      containers:
      - image: wordpress:5
        name: wordpress
        ports:
        - containerPort: 80

        envFrom:
        - prefix: 'WORDPRESS_DB_'
          configMapRef:
            name: wp-cm

最后设置service，实现负载均衡以及服务发现，并通过NodePort暴露端口号30088(必须在30000~32767之间)到宿主机，这样我们就可以在ingress访问不正常时通过访问该service来排查问题。如下：

apiVersion: v1
kind: Service
metadata:
  labels:
    app: wp-dep
  name: wp-svc

spec:
  ports:
  - name: http80
    port: 80
    protocol: TCP
    targetPort: 80
    nodePort: 30088

  selector:
    app: wp-dep
  type: NodePort

接着我们将三个yaml以---放在一个文件中，并apply，如下：

dongyunqi@mongodaddy:~/k8s$ kubectl apply -f  wp-dep.yml 
configmap/wp-cm created
deployment.apps/wp-dep created
service/wp-svc created
dongyunqi@mongodaddy:~/k8s$ kubectl get pod
NAME                         READY   STATUS    RESTARTS   AGE
maria-dep-767bbdccb5-dbm2t   1/1     Running   0          81m
wp-dep-5b5586d79c-fvj86      1/1     Running   0          2m23s
wp-dep-5b5586d79c-qf2zt      1/1     Running   0          2m23s
dongyunqi@mongodaddy:~/k8s$ kubectl get deploy
NAME        READY   UP-TO-DATE   AVAILABLE   AGE
maria-dep   1/1     1            1           81m
wp-dep      2/2     2            2           2m34s
dongyunqi@mongodaddy:~/k8s$ kubectl get service
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP        46h
maria-svc    ClusterIP   10.108.87.240   <none>        3306/TCP       81m
wp-svc       NodePort    10.99.4.117     <none>        80:30088/TCP   2m48s

接着我们就可以通过任意一个节点的30088端口来访问WordPress网站了，如下：

最后我们来部署流量真正的入口ingress。

3：部署ingress

首先定义ingress class：

apiVersion: networking.k8s.io/v1
kind: IngressClass
metadata:
  name: wp-ink

spec:
  controller: nginx.org/ingress-controller

然后用kubectl create命令生成ingress样板文件，指定域名是wp.test，后端Service是wp-svc:80，Ingress Class就是刚定义的wp-ink，如下：

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: wp-ing

spec:
  ingressClassName: wp-ink

  rules:
  - host: wp.test
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: wp-svc
            port:
              number: 80

最后定义ingress controller yaml,如下：

dongyunqi@mongodaddy:~/k8s$ cat my-ingress-controller.yml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: wp-ing
  namespace: nginx-ingress
spec:
  replicas: 1
  selector:
    matchLabels:
      app: ngx-kic-dep
  template:
    metadata:
      labels:
        app: ngx-kic-dep
    spec:
      hostNetwork: true
      serviceAccountName: nginx-ingress
      automountServiceAccountToken: true
      containers:
      - image: nginx/nginx-ingress:2.2-alpine
        imagePullPolicy: IfNotPresent
        name: nginx-ingress
        ports:
        - name: http
          containerPort: 80
        - name: https
          containerPort: 443
        - name: readiness-port
          containerPort: 8081
        - name: prometheus
          containerPort: 9113
        readinessProbe:
          httpGet:
            path: /nginx-ready
            port: readiness-port
          periodSeconds: 1
        resources:
          requests:
            cpu: "100m"
            memory: "128Mi"
        securityContext:
          allowPrivilegeEscalation: true
          runAsUser: 101 #nginx
          runAsNonRoot: true
          capabilities:
            drop:
            - ALL
            add:
            - NET_BIND_SERVICE
        env:
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        args:
          - -nginx-configmaps=$(POD_NAMESPACE)/nginx-config
          - -default-server-tls-secret=$(POD_NAMESPACE)/default-server-secret
          - -ingress-class=wp-ink

注意Nginx的pod配置了hostNetwork: true即和宿主机共享网络。分别apply后还不能直接访问，还需要配置hosts，将域名wp.test映射到Nginx的pod所在的Node的IP（通过-o wide查看POD会显示所在Node的IP地址信息），如下：

192.168.64.132 wp.test

测试如下：

这里页面报错是WordPress的，因为是我本地机器的资源不足，导致MariaDB的POD停止了，不过不影响我们测试，毕竟已经访问到WordPress了。

写在后面