【原文链接】
一、Dockerfile基础知识
- 每个保留关键字（指令）都是必须是大写字母
- 执行从上到下顺序执行
- \#表示注释
- 每个指令都会创建提交一个新的额镜像层，并提交
二、Dockerfile常用的指令
（1） FROM 指定基础镜像
FROM centos （2）MAINTAINER 指定镜像的维护者信息，一般为邮箱
MAINTAINER hitredrose@163.com（3）RUN 镜像构建时需要执行的命令
RUN yum install -y wget（4）ADD 增加文件，会自动解压
ADD python.tar.gz /usr/local/（5）WORKDIR 设置当前工作目录
WORKDIR /usr/local/python/（6）VOLUME 挂载主机目录
VOLUME ["/usr/local/python","/usr/local/java/"]（7）EXPOSE 暴露端口，注意这里指仅暴露容器的端口，并不会将容器端口与宿主机端口映射。也就是说在使用docker run的时候仍然需要继续使用-p进行端口映射，换言之，EXPOSE更多的作用在于给Dockerfile开发者提供开发端口的提示提示作用
EXPOSE 80（8）CMD 指定容器启动的时候需要执行的命令，注意CMD只有最后一个命令会生效
CMD /bin/bash（9）ENTRYPOINT 指定容器启动时需要运行的命令，注意ENTRYPOINT命令可以追加命令，即如果有多条ENTRYPOINT命令会全部执行，这是ENTRYPOINT命令和CMD命令最大的区别
ENTRYPOINT cd /opt
ENTRYPOINT /bin/bash（10）ONBUILD 当构建一个被继承Dockerfile，这个时候就会运行ONBUILD指令
（11）COPY 类似ADD命令，将文件拷贝到镜像中
（11）ENV 构建的时候设置环境变量
三、Dockerfile实战测试
1、编写如下Dockerfile文件，创建自己的centos镜像
FROM centos
MAINTAINER redrose2100<hitredrose@163.com>
ENV JAVA_HOME /usr/local/jdk_1.8/
WORKDIR /usr/local
RUN yum install -y vim
RUN yum install -y net-tools
EXPOSE 80
CMD echo $JAVA_HOME
CMD echo "---end---"
CMD /bin/bash2、编译镜像
docker build -f Dockerfile -t mycentos:1.0 .如
[root@iZbp1flzt6x7pxmxfhmxeeZ opt]# docker build -f Dockerfile -t mycentos:1.0 .
Sending build context to Docker daemon 673.8MB
Step 1/10 : FROM centos
---> 5d0da3dc9764
Step 2/10 : MAINTAINER redrose2100<hitredrose@163.com>
---> Running in da64144bd09f
Removing intermediate container da64144bd09f
---> 27c3c3914066
Step 3/10 : ENV JAVA_HOME /usr/local/jdk_1.8/
---> Running in e2bc434f38ed
Removing intermediate container e2bc434f38ed
---> 5702a1a5fcb4
Step 4/10 : WORKDIR /usr/local
---> Running in 5e89bfc4bac3
Removing intermediate container 5e89bfc4bac3
---> 4c9ffec050e5
Step 5/10 : RUN yum install -y vim
---> Running in a7d01621e43c
CentOS Linux 8 - AppStream 3.3 MB/s | 9.5 MB 00:02
CentOS Linux 8 - BaseOS 2.6 MB/s | 7.5 MB 00:02
CentOS Linux 8 - Extras 8.6 kB/s | 10 kB 00:01
Last metadata expiration check: 0:00:01 ago on Thu Oct 28 15:40:46 2021.
Dependencies resolved.
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
vim-enhanced x86_64 2:8.0.1763-15.el8 appstream 1.4 M
Installing dependencies:
gpm-libs x86_64 1.20.7-17.el8 appstream 39 k
vim-common x86_64 2:8.0.1763-15.el8 appstream 6.3 M
vim-filesystem noarch 2:8.0.1763-15.el8 appstream 48 k
which x86_64 2.21-12.el8 baseos 49 k
Transaction Summary
================================================================================
Install 5 Packages
Total download size: 7.8 M
Installed size: 30 M
Downloading Packages:
(1/5): gpm-libs-1.20.7-17.el8.x86_64.rpm 325 kB/s | 39 kB 00:00
(2/5): vim-filesystem-8.0.1763-15.el8.noarch.rp 74 kB/s | 48 kB 00:00
(3/5): which-2.21-12.el8.x86_64.rpm 859 kB/s | 49 kB 00:00
(4/5): vim-enhanced-8.0.1763-15.el8.x86_64.rpm 1.5 MB/s | 1.4 MB 00:00
(5/5): vim-common-8.0.1763-15.el8.x86_64.rpm 6.0 MB/s | 6.3 MB 00:01
--------------------------------------------------------------------------------
Total 1.5 MB/s | 7.8 MB 00:05
warning: /var/cache/dnf/appstream-02e86d1c976ab532/packages/gpm-libs-1.20.7-17.el8.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID 8483c65d: NOKEY
CentOS Linux 8 - AppStream 1.6 MB/s | 1.6 kB 00:00
Importing GPG key 0x8483C65D:
Userid : "CentOS (CentOS Official Signing Key) <security@centos.org>"
Fingerprint: 99DB 70FA E1D7 CE22 7FB6 4882 05B5 55B3 8483 C65D
From : /etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
Key imported successfully
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Installing : which-2.21-12.el8.x86_64 1/5
Installing : vim-filesystem-2:8.0.1763-15.el8.noarch 2/5
Installing : vim-common-2:8.0.1763-15.el8.x86_64 3/5
Installing : gpm-libs-1.20.7-17.el8.x86_64 4/5
Running scriptlet: gpm-libs-1.20.7-17.el8.x86_64 4/5
Installing : vim-enhanced-2:8.0.1763-15.el8.x86_64 5/5
Running scriptlet: vim-enhanced-2:8.0.1763-15.el8.x86_64 5/5
Running scriptlet: vim-common-2:8.0.1763-15.el8.x86_64 5/5
Verifying : gpm-libs-1.20.7-17.el8.x86_64 1/5
Verifying : vim-common-2:8.0.1763-15.el8.x86_64 2/5
Verifying : vim-enhanced-2:8.0.1763-15.el8.x86_64 3/5
Verifying : vim-filesystem-2:8.0.1763-15.el8.noarch 4/5
Verifying : which-2.21-12.el8.x86_64 5/5
Installed:
gpm-libs-1.20.7-17.el8.x86_64 vim-common-2:8.0.1763-15.el8.x86_64
vim-enhanced-2:8.0.1763-15.el8.x86_64 vim-filesystem-2:8.0.1763-15.el8.noarch
which-2.21-12.el8.x86_64
Complete!
Removing intermediate container a7d01621e43c
---> d5265b632c5d
Step 6/10 : RUN yum install -y net-tools
---> Running in e4936d8440ef
Last metadata expiration check: 0:00:42 ago on Thu Oct 28 15:40:46 2021.
Dependencies resolved.
================================================================================
Package Architecture Version Repository Size
================================================================================
Installing:
net-tools x86_64 2.0-0.52.20160912git.el8 baseos 322 k
Transaction Summary
================================================================================
Install 1 Package
Total download size: 322 k
Installed size: 942 k
Downloading Packages:
net-tools-2.0-0.52.20160912git.el8.x86_64.rpm 1.9 MB/s | 322 kB 00:00
--------------------------------------------------------------------------------
Total 285 kB/s | 322 kB 00:01
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 e4936d8440ef
---> c46a704ec937
Step 7/10 : EXPOSE 80
---> Running in 4abcb3b7a496
Removing intermediate container 4abcb3b7a496
---> 9f90477f2a46
Step 8/10 : CMD echo $JAVA_HOME
---> Running in 808052b626b3
Removing intermediate container 808052b626b3
---> ed2f970d17e1
Step 9/10 : CMD echo "---end---"
---> Running in 29c9a4149056
Removing intermediate container 29c9a4149056
---> 72af12cddaf8
Step 10/10 : CMD /bin/bash
---> Running in 6bc2bc8e3d73
Removing intermediate container 6bc2bc8e3d73
---> 122504aa874c
Successfully built 122504aa874c
Successfully tagged mycentos:1.0
[root@iZbp1flzt6x7pxmxfhmxeeZ opt]#然后执行docker images 查看如下：
[root@iZbp1flzt6x7pxmxfhmxeeZ opt]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
mycentos 1.0 122504aa874c About a minute ago 337MB
redrose2100/centos 1.1 2184c3aadaab 30 hours ago 231MB
nginx latest f8f4ffc8092c 4 weeks ago 133MB
mysql 5.7 9f35042c6a98 4 weeks ago 448MB
centos latest 5d0da3dc9764 6 weeks ago 231MB
[root@iZbp1flzt6x7pxmxfhmxeeZ opt]#
3、测试运行
如下，当前工作目录已经切换到 /usr/local 目录下，JAVA_HOME变量也是有值的，ifconfig命令也支持了
[root@iZbp1flzt6x7pxmxfhmxeeZ opt]# docker run -it mycentos:1.0
[root@b868b5ba93e9 local]# pwd
/usr/local
[root@b868b5ba93e9 local]# echo $JAVA_HOME
/usr/local/jdk_1.8/
[root@b868b5ba93e9 local]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 172.17.0.3 netmask 255.255.0.0 broadcast 172.17.255.255
ether 02:42:ac:11:00:03 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@b868b5ba93e9 local]#