一、详解
kubelet的配置中有这样一个参数
[root@linux-node1 cfg]# more /usr/lib/systemd/system/kubelet.service
--pod-infra-container-image=registry.cn-hangzhou.aliyuncs.com/google_containers/pause-amd64:3.1 二、Pause容器的作用
检查node节点的时候会发现每个node上都运行了很多的pause容器，例如：
[root@linux-node1 cfg]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a007c18b8dc0 568c4670fa80 "nginx -g ‘daemon of…" 42 hours ago Up 42 hours k8s_nginx_nginx-pod-7d9f9876cc-75sf7_default_a688bb46-f872-11e8-ae6b-000c29c6d12b_1
9866c08d1f4b 568c4670fa80 "nginx -g ‘daemon of…" 42 hours ago Up 42 hours k8s_nginx_nginx-pod-7d9f9876cc-wpv4h_default_a6a899c0-f872-11e8-ae6b-000c29c6d12b_1
aafef6727026 mirrorgooglecontainers/pause-amd64:3.0 "/pause" 42 hours ago Up 42 hours k8s_POD_flask-app-6f5b6cc447-kbxks_flask-app-extions-stage_374b8aa0-f873-11e8-ae6b-000c29c6d12b_1
c4f48f90b27f mirrorgooglecontainers/pause-amd64:3.0 "/pause" 42 hours ago Up 42 hours k8s_POD_flask-app-6f5b6cc447-f9wjn_flask-app-extions-stage_373be9db-f873-11e8-ae6b-000c29c6d12b_1
9f452e6961f6 mirrorgooglecontainers/pause-amd64:3.0 "/pause" 42 hours ago Up 42 hours k8s_POD_nginx-pod-7d9f9876cc-ccx94_default_a6a8c440-f872-11e8-ae6b-000c29c6d12b_1
7e68043469d1 mirrorgooglecontainers/pause-amd64:3.0 "/pause" 42 hours ago Up 42 hours k8s_POD_nginx-pod-7d9f9876cc-sskpk_default_a6ac43bd-f872-11e8-ae6b-000c29c6d12b_1
kubernetes中的pause容器主要为每个业务容器提供以下功能：
三、案例
1、在节点上运行一个pause容器
[root@k8s-node1 ~]# docker run -d --name pause -p 8880:80 registry.cn-hangzhou.aliyuncs.com/google_containers/pause-amd64:3.1
38d2aa8366d5aa6fe4c57aa0d879de4b5259c67c83d17428dd4d9f8937205c02
[root@k8s-node1 ~]# docker ps | grep pause
38d2aa8366d5 registry.cn-hangzhou.aliyuncs.com/google_containers/pause-amd64:3.1 "/pause" 14 seconds ago Up 13 seconds 0.0.0.0:8880->80/tcp pause
2、然后再运行一个nginx容器，nginx将为localhost:2368创建一个代理。
[root@k8s-node1 ~]# cat <<EOF >> nginx.conf
error_log stderr;
events { worker_connections 1024; }
http {
access_log /dev/stdout combined;
server {
listen 80 default_server;
server_name example.com www.example.com;
location / {
proxy_pass http://127.0.0.1:2368;
}
}
}
EOF
[root@k8s-node1 ~]# docker run -d --name nginx -v `pwd`/nginx.conf:/etc/nginx/nginx.conf --net=container:pause --ipc=container:pause --pid=container:pause nginx
fa078473c01e040db795004ad16db525dea8a113893d3052cc6ab1c5e117ba10
3、再为ghost创建一个应用容器，这是一款博客软件
[root@linux-node2 ~]# docker run -d --name ghost --net=container:pause --ipc=container:pause --pid=container:pause ghost
4、查看结果
[root@k8s-node1 ~]# docker ps | grep -E "pause|nginx|ghost"
9b796efd95a5 ghost "docker-entrypoint..." 47 seconds ago Up 46 seconds ghost
fa078473c01e nginx "nginx -g ‘daemon ..." About a minute ago Up About a minute nginx
38d2aa8366d5 registry.cn-hangzhou.aliyuncs.com/google_containers/pause-amd64:3.1 "/pause" 3 minutes ago Up 3 minutes 0.0.0.0:8880->80/tcp pause
5、现在访问http://119.3.198.128:8880/就可以看到ghost博客的界面或者直接用 curl 然后浏览器访问也可以
[root@k8s-node1 ~]# curl -I http://119.3.198.128:8880/
HTTP/1.1 200 OK
Server: nginx/1.15.5
Date: Fri, 07 Dec 2018 08:35:49 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 17381
Connection: keep-alive
X-Powered-By: Express
Cache-Control: public, max-age=0
ETag: W/"43e5-ELHSnbaoapp3YOyz+PU502oJo5E"
Vary: Accept-Encoding
6、进入ghost容器中查看
[root@k8s-node1 ~]# docker exec -it ghost /bin/bash
root@38d2aa8366d5:/var/lib/ghost# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 1012 4 ? Ss 08:27 0:00 /pause
root 5 0.0 0.0 32472 3168 ? Ss 08:29 0:00 nginx: master process nginx -g daemon off;
systemd+ 9 0.0 0.0 32932 1812 ? S 08:29 0:00 nginx: worker process
node 10 0.5 2.1 1262748 84688 ? Ssl 08:30 0:03 node current/index.js
root 83 0.2 0.0 20240 1912 pts/0 Ss 08:41 0:00 /bin/bash
root 87 0.0 0.0 17496 1148 pts/0 R+ 08:41 0:00 ps aux
在ghost容器中同时可以看到pause和nginx容器的进程，并且pause容器的PID是1。而在kubernetes中容器的PID=1的进程即为容器本身的业务进程。
注释2：
注释3：
原文：https://www.cnblogs.com/lfl17718347843/p/14458085.html