目录
1. Dockerfile的基本介绍
Dockerfile是用来构建Docker镜像的文本文件，是由一条条构建镜像所需的指令和参数构成的脚本
Dockerfile定义了进程需要的一切东西。Dockerfile涉及的内容包括执行代码或者是文件、环境变量、依赖包、运行时环境、动态链接库、操作系统的发行版、服务进程和内核进程(当应用进程需要和系统服务或内核进程打交道，这时需要考虑如何设计namespace的权限控制)等
详细介绍参考官网Dockerfile讲解
2. Dockerfile编写的基础知识
- 每条保留字指令都必须为大写字母，且后面要跟随至少一个参数
- 指令按照从上到下的顺序进行执行
- 注释用#表示
3. Docker build Dockerfile的流程
第一次循环：
- Docker从基础镜像运行一个容器
- 执行一条指令并对容器作出修改
- 执行类似docker commit的操作，提交一个新的镜像层
- 将原来的容器进行删除
第二次循环：
- docker再基于刚提交的镜像运行一个新容器
- 执行dockerfile中的下一条指令，操作的方法和前面的一样
第N次循环：
- 直到所有的指令都执行完成
2. 通过Dockerfile构建具有Java11的rockylinux镜像实战
2.1 目标
通过Dockerfile，基于rockylinux基础镜像，构建出具有Java11和ifconfig的新镜像
2.2 Java11的安装包准备
[root@docker ~]#
[root@docker ~]# mkdir java11_rockylinux
[root@docker ~]#
[root@docker ~]# cd java11_rockylinux/
[root@docker java11_rockylinux]#
[root@docker java11_rockylinux]# wget https://cdn.azul.com/zulu/bin/zulu11.56.19-ca-jdk11.0.15-linux_x64.tar.gz
[root@docker java11_rockylinux]#
2.3 Dockerfile
内容如下：
[root@docker java11_rockylinux]#
[root@docker java11_rockylinux]# cat Dockerfile
FROM rockylinux
MAINTAINER bulut<[email protected]>
ENV MY_WORK_DIR /root
WORKDIR $MY_WORK_DIR
# 安装ifconfig命令
RUN yum -y install net-tools
#安装java11。其中tar.gz包必须和Dockerfile位于同一目录
ADD zulu11.56.19-ca-jdk11.0.15-linux_x64.tar.gz /root/java11
#配置java环境变量
ENV JAVA_HOME /root/java11/zulu11.56.19-ca-jdk11.0.15-linux_x64
ENV PATH $PATH:$JAVA_HOME/bin
EXPOSE 80
CMD /bin/bash
[root@docker java11_rockylinux]#
2.4 docker build构建镜像
[root@docker java11_rockylinux]#
[root@docker java11_rockylinux]# docker build -t java11_rockylinux:0.1 .
Sending build context to Docker daemon 198.8MB
Step 1/10 : FROM rockylinux
---> 210996f98b85
Step 2/10 : MAINTAINER bulut<[email protected]>
---> Running in c05dbb563066
Removing intermediate container c05dbb563066
---> 2f05cc4414d9
Step 3/10 : ENV MY_WORK_DIR /root
---> Running in 88d51157e650
Removing intermediate container 88d51157e650
---> 25d02f13a1e7
Step 4/10 : WORKDIR $MY_WORK_DIR
---> Running in f7aba17e5b61
Removing intermediate container f7aba17e5b61
---> fb0b1fbb1a9c
Step 5/10 : RUN yum -y install net-tools
---> Running in 6a64c38cb289
Rocky Linux 8 - AppStream 2.4 MB/s | 10 MB 00:04
Rocky Linux 8 - BaseOS 1.8 MB/s | 7.7 MB 00:04
Rocky Linux 8 - Extras 9.4 kB/s | 12 kB 00:01
Dependencies resolved.
================================================================================
Package Architecture Version Repository Size
================================================================================
Installing:
net-tools x86_64 2.0-0.52.20160912git.el8 baseos 321 k
Transaction Summary
================================================================================
Install 1 Package
Total download size: 321 k
Installed size: 942 k
Downloading Packages:
net-tools-2.0-0.52.20160912git.el8.x86_64.rpm 514 kB/s | 321 kB 00:00
--------------------------------------------------------------------------------
Total 188 kB/s | 321 kB 00:01
Rocky Linux 8 - BaseOS 1.6 MB/s | 1.6 kB 00:00
Importing GPG key 0x6D745A60:
Userid : "Release Engineering <[email protected]>"
Fingerprint: 7051 C470 A929 F454 CEBE 37B7 15AF 5DAC 6D74 5A60
From : /etc/pki/rpm-gpg/RPM-GPG-KEY-rockyofficial
Key imported successfully
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Installing : net-tools-2.0-0.52.20160912git.el8.x86_64 1/1
Running scriptlet: net-tools-2.0-0.52.20160912git.el8.x86_64 1/1
Verifying : net-tools-2.0-0.52.20160912git.el8.x86_64 1/1
Installed:
net-tools-2.0-0.52.20160912git.el8.x86_64
Complete!
Removing intermediate container 6a64c38cb289
---> 44b044b5d67a
Step 6/10 : ADD zulu11.56.19-ca-jdk11.0.15-linux_x64.tar.gz /root/java11
---> f8373799c02c
Step 7/10 : ENV JAVA_HOME /root/java11/zulu11.56.19-ca-jdk11.0.15-linux_x64
---> Running in 4918ee062592
Removing intermediate container 4918ee062592
---> e0ed0ec11329
Step 8/10 : ENV PATH $PATH:$JAVA_HOME/bin
---> Running in 61605799a5e5
Removing intermediate container 61605799a5e5
---> e99cbac19847
Step 9/10 : EXPOSE 80
---> Running in 5d63fc8cd8fc
Removing intermediate container 5d63fc8cd8fc
---> f65fe884a458
Step 10/10 : CMD /bin/bash
---> Running in 2da56874d147
Removing intermediate container 2da56874d147
---> 7b8d925410ff
Successfully built 7b8d925410ff
Successfully tagged java11_rockylinux:0.1
[root@docker java11_rockylinux]#
2.5 通过新镜像运行容器并测试
[root@docker java11_rockylinux]#
[root@docker java11_rockylinux]# docker images java11_rockylinux
REPOSITORY TAG IMAGE ID CREATED SIZE
java11_rockylinux 0.1 7b8d925410ff About a minute ago 581MB
[root@docker java11_rockylinux]#
[root@docker java11_rockylinux]# docker run -it 7b8d925410ff bash
[root@7b576685d9bc ~]#
[root@7b576685d9bc ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.17.0.2 netmask 255.255.0.0 broadcast 172.17.255.255
ether 02:42:ac:11:00:02 txqueuelen 0 (Ethernet)
RX packets 8 bytes 656 (656.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
loop txqueuelen 1000 (Local Loopback)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@7b576685d9bc ~]#
[root@7b576685d9bc ~]# java -version
openjdk version "11.0.15" 2022-04-19 LTS
OpenJDK Runtime Environment Zulu11.56+19-CA (build 11.0.15+10-LTS)
OpenJDK 64-Bit Server VM Zulu11.56+19-CA (build 11.0.15+10-LTS, mixed mode)
[root@7b576685d9bc ~]#