docker镜像与制作

Docker镜像概念

镜像是没有内核的，与宿主机公用一个内核 
为什么没有内核？ 
  由于容器启动和运行过程中是直接使用了宿主机的内核，所以没有直接调用过
物理硬件，所以也不会涉及到硬件驱动，因此也用不上内核和驱动，另外有内核
的那是虚拟机。

验证镜像没有内核
[[email protected] ~]# docker ps -a 
CONTAINER ID   IMAGE          COMMAND                  CREATED      STATUS                  PORTS     NAMES
765452196b77   nginx:latest   "/docker-entrypoint.…"   2 days ago   Exited (0) 2 days ago             nginx-test
[[email protected] ~]# docker start 765452196b77
765452196b77
[[email protected] ~]# 
[[email protected] ~]# docker ps 
CONTAINER ID   IMAGE          COMMAND                  CREATED      STATUS         PORTS                               NAMES
765452196b77   nginx:latest   "/docker-entrypoint.…"   2 days ago   Up 2 seconds   0.0.0.0:81->80/tcp, :::81->80/tcp   nginx-test
[[email protected] ~]# 
[[email protected] ~]# docker exec  -it 765452196b77 /bin/bash
root@765452196b77:/# ls /boot
root@765452196b77:/boot# ls 
root@765452196b77:/boot# exit 

docker运行nginx为什么要添加daemon of;
docker 容器默认会把容器内部第一个进程，也就是pid=1的程序作为docker容器是否正在运行的依据，如果docker 容器pid挂了，那么docker容器便会直接退出。

制作Nginx镜像
1、先下载centos镜像

[[email protected] ~]# docker pull centos:7
[[email protected] ~]# docker image ls 
REPOSITORY   TAG       IMAGE ID       CREATED         SIZE
nginx        latest    605c77e624dd   8 months ago    141MB
centos       7         eeb6ee3f44bd   12 months ago   204MB  #pull下的centos7镜像
centos       latest    5d0da3dc9764   12 months ago   231MB

2、基于镜像启动centos7容器

[[email protected] ~]# docker run -d    -it     centos:7  
66fb85930b0b10a81d334138b272ab87b8eee412e6517f05e0d15e598f71ee4b
[[email protected] ~]# docker ps 
CONTAINER ID   IMAGE      COMMAND       CREATED         STATUS         PORTS     NAMES
66fb85930b0b   centos:7   "/bin/bash"   3 seconds ago   Up 2 seconds             suspicious_lichterman

3、进入容器更换yum源安装Nginx

[[email protected] ~]# docker ps 
CONTAINER ID   IMAGE      COMMAND       CREATED         STATUS         PORTS     NAMES
66fb85930b0b   centos:7   "/bin/bash"   3 seconds ago   Up 2 seconds             suspicious_lichterman
[[email protected] ~]# docker exec  -it 66fb85930b0b  /bin/bash

更换yum源，目前是没有Nginx源的
[root@66fb85930b0b /]# yum install nginx
Loaded plugins: fastestmirror, ovl
Loading mirror speeds from cached hostfile
 * base: mirrors.huaweicloud.com
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.huaweicloud.com
No package nginx available.
Error: Nothing to do

yum install wget   #下载命令

创建存放旧源目录，然后移动到指定的位置
[root@66fb85930b0b yum.repos.d]# mkdir /tmp/yum
[root@66fb85930b0b /]# cd /etc/yum.repos.d/
[root@66fb85930b0b yum.repos.d]# mv * /tmp/yum

更换yum源
[root@66fb85930b0b yum.repos.d]# wget  -O /etc/yum.repos.d/CentOS-Base.repo   http://mirrors.aliyun.com/repo/Centos-7.repo 
[root@66fb85930b0b yum.repos.d]# wget  -O /etc/yum.repos.d/epel.repo  http://mirrors.aliyun.com/repo/epel-7.repo 


安装并配置Nginx
[root@66fb85930b0b yum.repos.d]# yum -y install tree nmap sysstat lrzsz dos2unix telnet bash-completion bash-completion-extras vim nc  net-tools rsync
[root@66fb85930b0b yum.repos.d]# yum install nginx -y

关闭Nginx后台运行
[root@66fb85930b0b yum.repos.d]# head /etc/nginx/nginx.conf
# For more information on configuration, see:
#   * Official English Documentation: http://nginx.org/en/docs/
#   * Official Russian Documentation: http://nginx.org/ru/docs/

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
daemon off;   # 关闭后台运行

自定义web界面
[root@66fb85930b0b html]# cat index.html
wish_Docker_Nginx
[root@66fb85930b0b html]# pwd 
/usr/share/nginx/html
然后退出

4、打包镜像

[[email protected] ~]# docker commit -m "centos" 66fb85930b0b wish/centos-nginx:v1
sha256:bad0b3835b53c7f69961c133478f0cbc1192a01b7e5de267598b4db3af6fc869
[[email protected] ~]# docker image ls 
REPOSITORY          TAG       IMAGE ID       CREATED         SIZE
wish/centos-nginx   v1        bad0b3835b53   4 seconds ago   567MB   # 上一步打包的镜像
nginx               latest    605c77e624dd   8 months ago    141MB
centos              7         eeb6ee3f44bd   12 months ago   204MB
centos              latest    5d0da3dc9764   12 months ago   231MB

5、启动Nginx

[[email protected] ~]# docker run -d -it -p82:80 bad0b3835b53  /usr/sbin/nginx
764cd238d07fed8c450d4f64faf1ac13a6f819f2c6fa9c3cabccc5dc453e23a5
[[email protected] ~]# docker ps 
CONTAINER ID   IMAGE          COMMAND             CREATED          STATUS          PORTS                               NAMES
764cd238d07f   bad0b3835b53   "/usr/sbin/nginx"   2 seconds ago    Up 2 seconds    0.0.0.0:82->80/tcp, :::82->80/tcp   exciting_proskuriakova   # 启动的Nginx
66fb85930b0b   centos:7       "/bin/bash"         33 minutes ago   Up 33 minutes                                       suspicious_lichterman

6、浏览器访问
10.0.0.119:82

这样就打工告成啦！