Dockerfile 定制Nginx镜像

前言：

Dockerfile 是用于编写 Docker 镜像生成过程的文件，包含特定语法。在包含 Dockerfile 的文件夹中执行 docker build -t name:tag . 即可构建镜像。制作镜像需理解镜像分层概念，镜像由多层组成，理论上最多 127 层。

查看镜像层数的方法：

1. docker history 命令（只看 SIZE 大于 0 的行）：

   [root@localhost docker_images]# docker history centos_nginx:1.20
   IMAGE          CREATED         CREATED BY                                      SIZE      COMMENT
   ac20103ed758   3 days ago      /bin/sh -c #(nop)  CMD ["bin/sh" "-c" "ngin…    0B          
   ec1fd1e45ed5   3 days ago      /bin/sh -c #(nop)  EXPOSE 80                     0B          
   58618fd69d9c   3 days ago      /bin/sh -c #(nop) WORKDIR /usr/local/nginx/      0B          
   2da69b9e24e2   3 days ago      /bin/sh -c #(nop)  ENV PATH=/usr/local/sbin:…    0B          
   52ae7bfba773   3 days ago      /bin/sh -c ./configure --prefix=/usr/local/n…   27.9MB     
   db85c3ef27c6   3 days ago      /bin/sh -c #(nop) WORKDIR /usr/local/nginx-1…   0B          
   52b0a917d776   3 days ago      /bin/sh -c #(nop) ADD file:8c96cbcb0fc1f4a79…   6.4MB      
   930032c3aa9b   3 days ago      /bin/sh -c ./configure && make && make insta…   9.69MB     
   47f1e266ba57   3 days ago      /bin/sh -c #(nop) WORKDIR /usr/local/pcre-8.…   0B          
   03a8be5705b9   3 days ago      /bin/sh -c #(nop) ADD file:e5f245127035870b4…   9.05MB     
   f629d8acca91   3 days ago      /bin/sh -c yum -y install make zlib zlib-dev…   374MB      
   6c9f58d58724   3 days ago      /bin/sh -c #(nop)  MAINTAINER LDX<xxx.163.co…   0B          
   25c1784b5045   10 days ago     bash                                            548B      time calibration
   0c0f2dcf7afd   15 months ago    RUN /bin/sh -c yum install wget -y     && mv…   64.5MB    buildkit.dockerfile.v0
   <missing>      15 months ago    MAINTAINER "author=yangdejun update=2021-08-…   0B        buildkit.dockerfile.v0
   <missing>      2 years ago     /bin/sh -c #(nop)  CMD ["bin/bash"]            0B          
   <missing>      2 years ago     /bin/sh -c #(nop)  LABEL org.label-schema.sc…   0B          
   <missing>      2 years ago     /bin/sh -c #(nop) ADD file:72b194edf3abedf51…   203MB
   

2. docker inspect 命令（查看 RootFS 中的 Layers 字段）：

   [root@localhost docker_images]# docker inspect ac20103ed758
   "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:fb82b029bea0a2a3b6a62a9c1e47e57fae2a82f629b2d1a346da4fc8fb53a0b6",
                "sha256:c0cd7924335682967ab4689ff4a93cbabca6a29a856b59c8afe9bd19f50acef9",
                "sha256:199048ec1cd0a30e395c8576bc50fb41521a828da6d254d6cb87fcdeb87cbf2e",
                "sha256:7d14007007c4116285020229b0b80ca905c9e5da3e02f4420aab9794187a3ba5",
                "sha256:54bbee18d5e57c57dee2fd9dc78190ff73a9332ff74ea2caa03d038aabd59a7b",
                "sha256:ff5a2abea1cc7a2b998f497e372a6c2dd31ad1fac0eea080702876887964816e",
                "sha256:d94be22f19c5704ba8aa0504ddf23a635f2f73f1f02f201027b9af9f74800d80",
                "sha256:ba35802c1d21bb162e940819c067629fcf619d397b378847cfaa6b13512f8f79"
            ]
        },
        "Metadata": {
            "LastTagTime": "2022-11-04T11:50:22.594297543+08:00"
        }
    }
   ]
   

Dockerfile 指令简介：

任务环境：

基于 centos7.8 系统安装 Nginx 服务。

一、准备官方 centos7.8 镜像并校准时间

[root@localhost ~]# docker images
REPOSITORY                  TAG       IMAGE ID       CREATED         SIZE
martonyang/centos7.8.2003   latest    0c0f2dcf7afd   14 months ago   268MB

[root@localhost ~]# docker run -it martonyang/centos7.8.2003 bash

[root@ec22e09ae181 /]# cat /etc/redhat-release 
CentOS Linux release 7.8.2003 (Core)

校准时区：

[root@localhost ~]# docker run -it --name centos7 martonyang/centos7.8.2003 bash
[root@f3a8b1015053 /]# date
Fri Oct 28 08:11:27 UTC 2022
[root@f3a8b1015053 /]# mv /etc/localtime /root/localtime.bak
[root@f3a8b1015053 /]# cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
[root@f3a8b1015053 /]# date
Fri Oct 28 16:12:23 CST 2022

提交新镜像：

[root@localhost ~]# docker ps
CONTAINER ID   IMAGE                       COMMAND   CREATED         STATUS         PORTS     NAMES
f3a8b1015053   martonyang/centos7.8.2003   "bash"    4 minutes ago   Up 4 minutes           centos7

# 提交新镜像
[root@localhost ~]# docker commit -m="time calibration" -a="ldx" f3a8b1015053 centos:7.8
sha256:25c1784b504586e43b895a751280950a34e5bb33a632fb96f37c7cee82b10345

[root@localhost ~]# docker run --name centos7.8 -it 25c1784b5045 bash

# 时间准确
[root@b1874719f4d7 /]# date
Fri Oct 28 16:17:53 CST 2022

二、新建目录并编写 Dockerfile

注意：

Dockerfile 指令每执行一次会新建一层，避免无意义分层导致镜像膨胀。

[root@localhost ~]# mkdir /docker_images
[root@localhost ~]# cd /docker_images/

# 准备安装包
[root@localhost docker_images]# ls
nginx-1.20.2.tar.gz  pcre-8.35.tar.gz

[root@localhost docker_images]# vim Dockerfile
# 基于该镜像构成新的镜像
FROM centos:7.8

# 作者维护信息
MAINTAINER LDX<xxx.163.com>

# 安装依赖包
RUN yum -y install make zlib zlib-devel gcc-c++ libtool  openssl openssl-devel

# 导入并解压pcre-8.35文件
ADD pcre-8.35.tar.gz /usr/local/

# 切换到pcre-8.35目录，类似于CD效果
WORKDIR  /usr/local/pcre-8.35

# 编译安装
RUN ./configure && make && make install

# 导入并解压nginx-1.20文件
ADD nginx-1.20.2.tar.gz /usr/local/

# 切换到nginx-1.20.2目录
WORKDIR /usr/local/nginx-1.20.2

# 编译安装
RUN ./configure --prefix=/usr/local/nginx --with-http_stub_status_module --with-http_ssl_module --with-pcre=/usr/local/pcre-8.35 && make && make install

# 设置环境变量
ENV PATH $PATH:/usr/local/nginx/sbin

# 切换到nginx目录
WORKDIR /usr/local/nginx/

# 展示80端口
EXPOSE 80

# 使得nginx运行在前台，所有信息直接输出控制台
CMD nginx -g 'daemon off;'

启动命令注意事项：

三、根据 Dockerfile 构建新 Nginx 镜像

# docker build -t 新镜像的名字:版本号 . （注意有一个点）
docker build -t centos_nginx:1.20 .

四、基于新镜像创建并运行 Nginx 容器

[root@localhost docker_images]# docker ps
CONTAINER ID   IMAGE             COMMAND                  CREATED         STATUS         PORTS                                     NAMES
8e687e521a1a   centos_nginx:1.20   "/bin/sh -c 'nginx -…"   2 minutes ago   Up 2 minutes   0.0.0.0:49153->80/tcp, :::49153->80/tcp   naughty_sammet

效果图：