K8S本身動手系列 - 2.2 - Deployment

前言

前面的文章，咱們使用Pod完成了wordpress+mysql的部署，並將兩個容器放在了一個Pod當中，本篇文章，咱們將使用Deployment完成前面的部署工做

本文實驗全部的源碼保存在： github.com/zrbcool/blo…

實戰

查看deployment定義

➜  lab05 git:(master) ✗ cat 01-wordpress-mysql-deployment.yaml 
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  labels:
    app: wordpress
  name: wordpress
spec:
  replicas: 1
  selector:
    matchLabels:
      app: wordpress
  template:
    metadata:
      labels:
        app: wordpress 
    spec:
      containers:
      - image: wordpress:latest
        imagePullPolicy: IfNotPresent
        name: wordpress
        env:
          - name: WORDPRESS_DB_HOST
            value: "127.0.0.1"
          - name: WORDPRESS_DB_USER
            value: "root"
          - name: WORDPRESS_DB_PASSWORD
            value: "passw0rd"
      - image: mysql:5.7.26
        imagePullPolicy: IfNotPresent
        name: mysql
        env:
          - name: MYSQL_ROOT_PASSWORD 
            value: "passw0rd"
          - name: MYSQL_DATABASE
            value: "wordpress"
複製代碼

執行部署操做

➜  lab05 git:(master) ✗ kubectl apply -f 01-wordpress-mysql-deployment.yaml 
deployment.extensions/wordpress created
➜  lab05 git:(master) ✗ kubectl apply -f 02-wordpress-svc.yaml 
service/wordpress-svc created

➜  lab05 git:(master) ✗ kubectl get deploy -o wide
NAME        READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS        IMAGES                          SELECTOR
wordpress   1/1     1            1           2m15s   wordpress,mysql   wordpress:latest,mysql:5.7.26   app=wordpress
➜  lab05 git:(master) ✗ kubectl get pod -o wide
NAME                         READY   STATUS    RESTARTS   AGE     IP            NODE       NOMINATED NODE   READINESS GATES
wordpress-5844bb9d6b-dbfb4   2/2     Running   0          2m23s   10.244.0.62   worker01   <none>           <none>
➜  lab05 git:(master) ✗ kubectl get svc -o wide
NAME            TYPE        CLUSTER-IP     EXTERNAL-IP PORT(S) AGE SELECTOR wordpress-svc NodePort 10.98.150.68 <none> 80:30611/TCP 2m23s app=wordpress
複製代碼

訪問咱們的服務，

Deployment擴縮容嘗試

修改咱們的deployment定義，將replicas修改成2，查看效果

➜  lab05 git:(master) ✗ kubectl get deploy -o wide
NAME        READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS        IMAGES                          SELECTOR
wordpress   2/2     2            2           7m43s   wordpress,mysql   wordpress:latest,mysql:5.7.26   app=wordpress
➜  lab05 git:(master) ✗ kubectl get pod -o wide
NAME                         READY   STATUS    RESTARTS   AGE     IP            NODE       NOMINATED NODE   READINESS GATES
wordpress-5844bb9d6b-dbfb4   2/2     Running   0          7m47s   10.244.0.62   worker01   <none>           <none>
wordpress-5844bb9d6b-ttkvm   2/2     Running   0          11s     10.244.0.63   worker01   <none>           <none>
複製代碼

屢次訪問網頁，發現網頁進入了網站初始化界面，初始化網站爲mywebsite2，發現網站常常在website1與website2間切換，這是由於咱們的兩個副本從應用到數據庫徹底是相同的兩份，而Service負載均衡，會分配請求到兩套實例上，可是mysql是有狀態應用，就形成了咱們使用上的問題。

問題如何解決

實際上，Deployment就是用來部署無狀態應用的，它期待你的副本之間是沒有區別的，那麼在咱們的場景下，mysql使用Deployment來部署就不是一個好的實踐，咱們這裏只是學習使用，後續咱們會用StatefulSet來部署有狀態應用解決當前這個問題。