1. k8s-init初始化容器应用
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Init Container：顾名思义，用于初始化工作，执行完就结束，可以理解为一次性任务。
- 支持大部分应用容器配置，但不支持健康检查
- 优先应用容器执行
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应用场景：
- 环境检查：例如确保应用容器依赖的服务启动后再启动应用容器
- 初始化配置：例如给应用容器准备配置文件
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示例：部署一个web网站，网站程序没有打到镜像中，而是希望从代码仓库中动态拉取放到应用容器中
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示例代码：
apiVersion: v1 kind: Pod metadata: name: init-demo spec: initContainers: - name: download image: busybox command: - wget - "-O" - "/opt/index.html" - http://www.baidu.com volumeMounts: - name: wwwroot mountPath: "/opt" containers: - name: nginx image: nginx ports: - containerPort: 80 volumeMounts: - name: wwwroot mountPath: /usr/share/nginx/html volumes: - name: wwwroot emptyDir: {}
2. 案例
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编写配置文件
[root@k8s-master yaml]# vim pod-init.yaml [root@k8s-master yaml]# cat pod-init.yaml apiVersion: v1 kind: Pod metadata: name: init-demo spec: initContainers: - name: download image: busybox command: - wget - "-O" - "/opt/index.html" - http://www.baidu.com volumeMounts: - name: wwwroot mountPath: "/opt" containers: - name: nginx image: nginx ports: - containerPort: 80 volumeMounts: - name: wwwroot mountPath: /usr/share/nginx/html volumes: - name: wwwroot emptyDir: {} -
启动服务
[root@k8s-master yaml]# kubectl apply -f pod-init.yaml pod/init-demo created -
查看和验证服务
[root@k8s-master yaml]# kubectl get pods NAME READY STATUS RESTARTS AGE init-demo 1/1 Running 0 36s pod-envars 1/1 Running 0 38m probe-demo 1/1 Running 0 169m -
进入容器查看共享卷是否有数据了
[root@k8s-master yaml]# kubectl exec -it init-demo -- /bin/bash root@init-demo:/# ls /usr/share/nginx/html/ index.html root@init-demo:/# cat /usr/share/nginx/html/index.html <!DOCTYPE html> <!--STATUS OK--><html> <head><meta http-equiv=content-type content=text/html;charset=utf-8><meta http-equiv=X-UA-Compatible content=IE=Edge><meta content=always name=referrer><link rel=stylesheet type=text/css href=http://s1.bdstatic.com/r/www/cache/bdorz/baidu.min.css><title>百度一下，你就知道</title></head> <body link=#0000cc> <div id=wrapper> <div id=head> <div class=head_wrapper> <div class=s_form> <div class=s_form_wrapper> <div id=lg> <img hidefocus=true src=//www.baidu.com/img/bd_logo1.png width=270 height=129> </div> <form id=form name=f action=//www.baidu.com/s class=fm> <input type=hidden name=bdorz_come value=1> <input type=hidden name=ie value=utf-8> <input type=hidden name=f value=8> <input type=hidden name=rsv_bp value=1> <input type=hidden name=rsv_idx value=1> <input type=hidden name=tn value=baidu><span class="bg s_ipt_wr"><input id=kw name=wd class=s_ipt value maxlength=255 autocomplete=off autofocus></span><span class="bg s_btn_wr"><input type=submit id=su value=百度一下 class="bg s_btn"></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class=mnav>新闻</a> <a href=http://www.hao123.com name=tj_trhao123 class=mnav>hao123</a> <a href=http://map.baidu.com name=tj_trmap class=mnav>地图</a> <a href=http://v.baidu.com name=tj_trvideo class=mnav>视频</a> <a href=http://tieba.baidu.com name=tj_trtieba class=mnav>贴吧</a> <noscript> <a href=http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2f%3fbdorz_come%3d1 name=tj_login class=lb>登录</a> </noscript> <script>document.write('<a href="http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u='+ encodeURIComponent(window.location.href+ (window.location.search === "" ? "?" : "&")+ "bdorz_come=1")+ '" name="tj_login" class="lb">登录</a>');</script> <a href=//www.baidu.com/more/ name=tj_briicon class=bri style="display: block;">更多产品</a> </div> </div> </div> <div id=ftCon> <div id=ftConw> <p id=lh> <a href=http://home.baidu.com>关于百度</a> <a href=http://ir.baidu.com>About Baidu</a> </p> <p id=cp>©2017 Baidu <a href=http://www.baidu.com/duty/>使用百度前必读</a> <a href=http://jianyi.baidu.com/ class=cp-feedback>意见反馈</a> 京ICP证030173号 <img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html> -
小结：
- 注意，在编写yaml配置文件的时候，init服务，只能启动一次，如果有修改配置文件，需要删除容器，再次启动容器