K8S本身動手系列 - 2.1 - Pod

時間 2019-12-04

標籤 k8s 本身動手系列 2.1 pod 简体版

原文原文鏈接

說在最前

Pod做爲Kubernetes的一等公民，是K8S調度的最小單元，也是使用Kubernetes的人打交道最多的K8S模型。既然Pod這麼重要，搞清楚Pod的各類功能及操做就很是重要了，理解了Pod之後，各類Pod的控制器組件，例如：Deployment，StatefulSet，DaemonSet， Job，ReplicaSet理解起來才能事半功倍。php

正篇

閱讀官方文檔對Pod的描述，其闡述了Pod在集羣中的兩種主要使用方式：html

一個Pod運行一個容器
一個Pod運行多個須要在一塊兒的容器

因爲前面的實驗，咱們已經使用過Deployment部署簡單的nginx容器，這種就屬於第一種，一個Pod運行一個容器的模型，因此本篇文章咱們來實戰一下，一個Pod運行多個相互關聯的容器。java

實戰

場景說明

本文以經常使用blog應用wordpress+mysql爲例，將wordpress與mysql運行在同一個Pod內，並實現同Pod的相互訪問。mysql

本文實驗全部的源碼保存在： github.com/zrbcool/blo…nginx

建立wordpress的Pod

查看Pod的yaml定義：git

➜  lab04 git:(master) cat 01-wordpress-pod.yaml 
apiVersion: v1
kind: Pod
metadata:
 labels:
 app: wordpress
 name: wordpress 
spec:
 containers:
 - image: wordpress:latest 
 imagePullPolicy: IfNotPresent
 name: wordpress
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部署該Pod，並查看運行狀態github

➜  lab04 kubectl apply -f 01-wordpress-pod.yaml
pod/wordpress create
➜  lab04 kubectl get pods -o wide
NAME        READY   STATUS    RESTARTS   AGE     IP            NODE       NOMINATED NODE   READINESS GATES
wordpress   1/1     Running   0          2m21s   10.244.0.53   worker01   <none>           <none>
➜  lab04 http 10.244.0.53 
HTTP/1.1 302 Found
Connection: Keep-Alive
Content-Length: 0
Content-Type: text/html; charset=UTF-8
Date: Mon, 10 Jun 2019 05:37:54 GMT
Keep-Alive: timeout=5, max=100
Location: http://10.244.0.53/wp-admin/setup-config.php
Server: Apache/2.4.25 (Debian)
X-Powered-By: PHP/7.3.6
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爲了方便訪問，咱們再建立一個類型爲NodePort的Service（這塊不用糾結，後面會專門講到），sql

➜  lab04 git:(master) cat 02-wordpress-svc.yaml 
apiVersion: v1
kind: Service
metadata:
  name: wordpress-svc 
  labels:
    app: wordpress
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: wordpress
  type: NodePort

➜  lab04 kubectl apply -f 02-wordpress-svc.yaml 
service/wordpress-svc created
➜  lab04 kubectl get svc wordpress-svc
NAME            TYPE       CLUSTER-IP    EXTERNAL-IP PORT(S) AGE wordpress-svc NodePort 10.98.40.11 <none> 80:30466/TCP 108s 複製代碼

而後咱們用節點IP:30466就能夠進行訪問了，試試 docker

加入mysql的Pod

上面的步驟，咱們成功使用Pod資源模型部署了wordpress，可是wordpress是基於mysql的應用，咱們還須要一個mysql，針對這個實驗，咱們將mysql與wordpress部署在一個pod，這樣他們就能夠基於localhost進行通訊了，來試試看。數據庫

修改Pod定義，加入mysql

修改後的yaml請參考：

➜  lab04 git:(master) cat 03-wordpress-mysql-pod.yaml 
apiVersion: v1
kind: Pod
metadata:
 labels:
 app: wordpress
 name: wordpress 
spec:
 containers:
 - image: wordpress:latest 
 imagePullPolicy: IfNotPresent
 name: wordpress
 - image: mysql:5.7.26
 imagePullPolicy: IfNotPresent
 name: mysql
 env:
 - name: MYSQL_ROOT_PASSWORD 
 value: "passw0rd"
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執行部署，

➜  lab04 kubectl delete -f 03-wordpress-mysql-pod.yaml
pod "wordpress" deleted
➜  lab04 kubectl create -f 03-wordpress-mysql-pod.yaml
pod/wordpress created
➜  lab04 kubectl get pods -o wide
NAME        READY   STATUS    RESTARTS   AGE   IP            NODE       NOMINATED NODE   READINESS GATES
wordpress   2/2     Running   0          25s   10.244.0.55   worker01   <none>           <none>

➜  lab04 telnet 10.244.0.55 3306
Trying 10.244.0.55...
Connected to 10.244.0.55.
Escape character is '^]'.

➜  lab04 http 10.244.0.55
HTTP/1.1 302 Found
Connection: Keep-Alive
Content-Length: 0
Content-Type: text/html; charset=UTF-8
Date: Mon, 10 Jun 2019 06:14:58 GMT
Keep-Alive: timeout=5, max=100
Location: http://10.244.0.55/wp-admin/setup-config.php
Server: Apache/2.4.25 (Debian)
X-Powered-By: PHP/7.3.6
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可見兩個容器已經在同一個Pod內啓動，而且mysql的3306端口也是通的，wordpress的80也是OK的

進入wordpress設置界面進行配置

下一步

上圖說了，缺數據庫，來手工建立一個庫

➜  lab04 kubectl get pods -o wide
NAME        READY   STATUS    RESTARTS   AGE     IP            NODE       NOMINATED NODE   READINESS GATES
wordpress   2/2     Running   0          5m40s   10.244.0.57   worker01   <none>           <none>
➜  lab04 docker run -it --network host --rm mysql mysql -h10.244.0.57 -uroot -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.26 MySQL Community Server (GPL)

Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> create database wordpress;
Query OK, 1 row affected (0.00 sec)
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再來一次，成功了！

經過標籤過濾，查看下本次實驗咱們建立的全部資源：

➜  lab04 git:(master) kubectl get all -l app=wordpress
NAME            READY   STATUS    RESTARTS   AGE
pod/wordpress   2/2     Running   0          29m

NAME                    TYPE       CLUSTER-IP    EXTERNAL-IP PORT(S) AGE service/wordpress-svc NodePort 10.98.40.11 <none> 80:30466/TCP 67m 複製代碼