如何基于Dockerfile构建tomcat镜像

dockerfile 是用来构建docker镜像的文件！命令参数脚本！

构建步骤：

编写一个dockerfile 文件
docker build 构建成一个镜像
docker run 运行镜像
docker push 发布镜像（DockerHub、阿里云镜像仓库）

# 以contes为例查看 dockerhub 上 contes 的 dockerfile

FROM scratch

ADD centos-7-x86_64-docker.tar.xz /

LABEL \\

org.label-schema.schema-version="1.0" \\

org.label-schema.name="CentOS Base Image" \\

org.label-schema.vendor="CentOS" \\

org.label-schema.license="GPLv2" \\

org.label-schema.build-date="20200809" \\

org.opencontainers.image.title="CentOS Base Image" \\

org.opencontainers.image.vendor="CentOS" \\

org.opencontainers.image.licenses="GPL-2.0-only" \\

org.opencontainers.image.created="2020-08-09 00:00:00+01:00"

CMD ["/bin/bash"]

DockerFile构建过程

基础知识：

每个保留关键字（指令）都必须是大写字母
执行顺序从上到下顺序执行
表示注释
每个指令都会创建提交一个新的镜像层，并提交

dockerfile是面向开发的，我们以后要发布项目，做镜像，就需要编写dockerfile文件，这个文件十分简单！

Docker镜像逐渐成为企业交付的标准！

DockerFile：构建镜像，定义了一切的步骤，源代码；

DockerImages：通过DockerFile构建生成的一个镜像，这个镜像就是我们最终发布和运行的产品！

Docker容器：容器就是镜像运行起来提供服务！

DockerFile的指令

FROM # 基础镜像

MAINTAINER # 镜像是谁写的姓名 + 邮箱

RUN # 镜像构建的时候需要运行的命令

ADD # 步骤 eg:tomcat镜像---》放入tomcat的压缩包！添加内容

WORKDIR # 镜像的工作目录

VOLUME # 挂载的目录位置

EXPOST # 暴露端口配置

CMD # 指定这个容器启动的时候要运行的命令,只有最后一个会生效，可被替代

ENTRYPOINT # 指定这个容器启动的时候要运行的命令，可以追加命令

ONBUILD # 当构建一个被继承的 DockerFile ，这个时候就会运行 ONBUILD 的指令，触发指令

COPY # 类似ADD，将我们的文件拷贝到镜像中

ENV # 构建的时候设置环境变量

实战测试

Docker Hub 中 99% 的镜像都是从 FROM scratch 这个基础镜像过来的，然后配置我们需要的软件和配置来进行构建

创建一个自己的centos

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# 1、编写DockerFile的文件

FROM centos

# 作者信息

MAINTAINER yinxiaodong<m15010969094@163.com>

# 配置环境变量

ENV MYPATH /user/local

# 指定镜像的工作目录

WORKDIR $MYPATH

RUN yum install -y vim

RUN yum install -y net-tools

# 暴露80端口

EXPOSE 80

CMD echo $MYPATH

CMD echo "---------end--------"

CMD /bin/bash

# 2、通过文件构建镜像

# 命令 docker build -f dockerfile文件路径 -t 镜像名:版本号 .

[root@localhost dockerfile]# docker build -f mydockerfile-centos -t mycentos:0.1 .

Sending build context to Docker daemon 2.048kB

Step 1/9 : FROM centos

---> 0d120b6ccaa8

Step 2/9 : MAINTAINER yinxiaodong<m15010969094@163.com>

---> Running in f79b12ffb083

Removing intermediate container f79b12ffb083

---> 8ee53d3f7a65

Step 3/9 : ENV MYPATH /user/local

---> Running in 659a2c96d5f7

Removing intermediate container 659a2c96d5f7

---> 59ab131ef44c

Step 4/9 : WORKDIR $MYPATH

---> Running in 0b4b8f9c65bb

Removing intermediate container 0b4b8f9c65bb

---> 408b06671488

Step 5/9 : RUN yum install -y net-tools

---> Running in 151f81148a87

CentOS-8 - AppStream 118 kB/s | 5.8 MB 00:50

CentOS-8 - Base 218 kB/s | 2.2 MB 00:10

CentOS-8 - Extras 1.8 kB/s | 7.3 kB 00:04

Dependencies resolved.

================================================================================

Package Architecture Version Repository Size

================================================================================

Installing:

net-tools x86_64 2.0-0.51.20160912git.el8 BaseOS 323 k

Transaction Summary

================================================================================

Install 1 Package

Total download size: 323 k

Installed size: 1.0 M

Downloading Packages:

net-tools-2.0-0.51.20160912git.el8.x86_64.rpm 219 kB/s | 323 kB 00:01

--------------------------------------------------------------------------------

Total 66 kB/s | 323 kB 00:04

warning: /var/cache/dnf/BaseOS-f6a80ba95cf937f2/packages/net-tools-2.0-0.51.20160912git.el8.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID 8483c65d: NOKEY

CentOS-8 - Base 162 kB/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 : net-tools-2.0-0.51.20160912git.el8.x86_64 1/1

Running scriptlet: net-tools-2.0-0.51.20160912git.el8.x86_64 1/1

Verifying : net-tools-2.0-0.51.20160912git.el8.x86_64 1/1

Installed:

net-tools-2.0-0.51.20160912git.el8.x86_64

Complete!

Removing intermediate container 151f81148a87

---> c0a0546c9b2a

Step 6/9 : EXPOSE 80

---> Running in 42000936515d

Removing intermediate container 42000936515d

---> fe68114ecf3f

Step 7/9 : CMD echo $MYPATH

---> Running in c393fc53a354

Removing intermediate container c393fc53a354

---> a6924276bf90

Step 8/9 : CMD echo "---------end--------"

---> Running in 5994de56f0a1

Removing intermediate container 5994de56f0a1

---> a8ba0ebb3770

Step 9/9 : CMD /bin/bash

---> Running in d1fa2d436363

Removing intermediate container d1fa2d436363

---> 41bb76be4884

Successfully built 41bb76be4884

Successfully tagged mycentos:0.1

[root@localhost dockerfile]# docker images

REPOSITORY TAG IMAGE ID CREATED SIZE

mycentos 0.1 41bb76be4884 7 seconds ago 246MB

centos 1.0 d840628c30a9 6 hours ago 215MB

centos latest 0d120b6ccaa8 2 days ago 215MB

# 启动 mycentos 使用 ifconfig 命令查看ip信息

[root@localhost dockerfile]# docker run -it mycentos:0.1

[root@494c2bc72263 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 6 bytes 516 (516.0 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

# 查看所在目录 /user/local 正是我们在dockerfile中指定的目录

[root@494c2bc72263 local]# pwd

/user/local

查看镜像的构建历史记录

# 命令 docker history 镜像id

[root@localhost ~]# docker history 41bb76be4884

IMAGE CREATED CREATED BY SIZE COMMENT

41bb76be4884 16 minutes ago /bin/sh -c #(nop) CMD ["/bin/sh" "-c" "/bin… 0B

a8ba0ebb3770 16 minutes ago /bin/sh -c #(nop) CMD ["/bin/sh" "-c" "echo… 0B

a6924276bf90 16 minutes ago /bin/sh -c #(nop) CMD ["/bin/sh" "-c" "echo… 0B

fe68114ecf3f 16 minutes ago /bin/sh -c #(nop) EXPOSE 80 0B

c0a0546c9b2a 16 minutes ago /bin/sh -c yum install -y net-tools 31.3MB

408b06671488 17 minutes ago /bin/sh -c #(nop) WORKDIR /user/local 0B

59ab131ef44c 17 minutes ago /bin/sh -c #(nop) ENV MYPATH=/user/local 0B

8ee53d3f7a65 17 minutes ago /bin/sh -c #(nop) MAINTAINER yinxiaodong<m1… 0B

0d120b6ccaa8 2 days ago /bin/sh -c #(nop) CMD ["/bin/bash"] 0B

<missing> 2 days ago /bin/sh -c #(nop) LABEL org.label-schema.sc… 0B

<missing> 2 days ago /bin/sh -c #(nop) ADD file:538afc0c5c964ce0d… 215MB

我们平时拿到一个镜像，可以研究一下它是怎么做的—->docker history 镜像id

CMD 和 ENTRYPOINT 的区别

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CMD # 指定这个容器启动的时候要运行的命令,只有最后一个会生效，可被替代

ENTRYPOINT # 指定这个容器启动的时候要运行的命令，可以追加命令

# 测试 CMD

# 编写DockerFile的文件

[root@localhost dockerfile]# cat dockerfile-cmd-test

FROM centos

CMD ["ls","-a"]

# 根据 DockerFile 构建镜像

[root@localhost dockerfile]# docker build -f dockerfile-cmd-test -t testcmd:0.1 .

Sending build context to Docker daemon 3.072kB

Step 1/2 : FROM centos

---> 0d120b6ccaa8

Step 2/2 : CMD ["ls","-a"]

---> Running in b3f8ba72222b

Removing intermediate container b3f8ba72222b

---> 561e47f88730

Successfully built 561e47f88730

Successfully tagged testcmd:0.1 # 构建成功

# 查看镜像

[root@localhost dockerfile]# docker images

REPOSITORY TAG IMAGE ID CREATED SIZE

testcmd 0.1 561e47f88730 6 seconds ago 215MB

centos latest 0d120b6ccaa8 2 days ago 215MB

# 启动镜像发现ls -a命令生效

[root@localhost dockerfile]# docker run -it testcmd:0.1

. .dockerenv dev home lib64 media opt root sbin sys usr

.. bin etc lib lost+found mnt proc run srv tmp var

# 启动命令中 追加一个 -l, 我们期望的是 ls -a -l,但是 报错，这里将 ls -a 替换成了 -l，最终的命令是 -l 所以报错。

[root@localhost dockerfile]# docker run -it 561e47f88730 -l

docker: Error response from daemon: OCI runtime create failed: container_linux.go:349: starting container process caused

"exec: \\"-l\\": executable file not found in $PATH": unknown.

# 将启动命令替换成 docker run -it testcmd:0.1 ls -al，成功打印详细信息;

[root@localhost dockerfile]# docker run -it testcmd:0.1 ls -al

total 0

drwxr-xr-x. 1 root root 6 Aug 13 08:20 .

drwxr-xr-x. 1 root root 6 Aug 13 08:20 ..

-rwxr-xr-x. 1 root root 0 Aug 13 08:20 .dockerenv

lrwxrwxrwx. 1 root root 7 May 11 2019 bin -> usr/bin

drwxr-xr-x. 5 root root 360 Aug 13 08:20 dev

drwxr-xr-x. 1 root root 66 Aug 13 08:20 etc

drwxr-xr-x. 2 root root 6 May 11 2019 home

lrwxrwxrwx. 1 root root 7 May 11 2019 lib -> usr/lib

lrwxrwxrwx. 1 root root 9 May 11 2019 lib64 -> usr/lib64

drwx------. 2 root root 6 Aug 9 21:40 lost+found

drwxr-xr-x. 2 root root 6 May 11 2019 media

drwxr-xr-x. 2 root root 6 May 11 2019 mnt

drwxr-xr-x. 2 root root 6 May 11 2019 opt

dr-xr-xr-x. 123 root root 0 Aug 13 08:20 proc

dr-xr-x---. 2 root root 162 Aug 9 21:40 root

drwxr-xr-x. 11 root root 163 Aug 9 21:40 run

lrwxrwxrwx. 1 root root 8 May 11 2019 sbin -> usr/sbin

drwxr-xr-x. 2 root root 6 May 11 2019 srv

dr-xr-xr-x. 13 root root 0 Aug 11 09:58 sys

drwxrwxrwt. 7 root root 145 Aug 9 21:40 tmp

drwxr-xr-x. 12 root root 144 Aug 9 21:40 usr

drwxr-xr-x. 20 root root 262 Aug 9 21:40 var

# 测试二：现在我们把 DockerFile 中 CMD 替换成 ENTRYPOINT 后重新构建，运行看看结果

[root@localhost dockerfile]# cat dockerfile-cmd-test

FROM centos

ENTRYPOINT ["ls","-a"]

# 重新构建镜像

[root@localhost dockerfile]# docker build -f dockerfile-cmd-test -t testcmd:0.2 .

Sending build context to Docker daemon 3.072kB

Step 1/2 : FROM centos

---> 0d120b6ccaa8

Step 2/2 : ENTRYPOINT ["ls","-a"]

---> Running in c634ca09fabe

Removing intermediate container c634ca09fabe

---> 52d295395f08

Successfully built 52d295395f08

Successfully tagged testcmd:0.2

# 查看镜像

[root@localhost dockerfile]# docker images

REPOSITORY TAG IMAGE ID CREATED SIZE

testcmd 0.2 52d295395f08 7 seconds ago 215MB

testcmd 0.1 561e47f88730 12 minutes ago 215MB

centos latest 0d120b6ccaa8 2 days ago 215MB

# 运行testcmd：0.2镜像并追加 -l ,发现打印出了详细信息

[root@localhost dockerfile]# docker run -it testcmd:0.2 -l

total 0

drwxr-xr-x. 1 root root 6 Aug 13 08:17 .

drwxr-xr-x. 1 root root 6 Aug 13 08:17 ..

-rwxr-xr-x. 1 root root 0 Aug 13 08:17 .dockerenv

lrwxrwxrwx. 1 root root 7 May 11 2019 bin -> usr/bin

drwxr-xr-x. 5 root root 360 Aug 13 08:17 dev

drwxr-xr-x. 1 root root 66 Aug 13 08:17 etc

drwxr-xr-x. 2 root root 6 May 11 2019 home

lrwxrwxrwx. 1 root root 7 May 11 2019 lib -> usr/lib

lrwxrwxrwx. 1 root root 9 May 11 2019 lib64 -> usr/lib64

drwx------. 2 root root 6 Aug 9 21:40 lost+found

drwxr-xr-x. 2 root root 6 May 11 2019 media

drwxr-xr-x. 2 root root 6 May 11 2019 mnt

drwxr-xr-x. 2 root root 6 May 11 2019 opt

dr-xr-xr-x. 121 root root 0 Aug 13 08:17 proc

dr-xr-x---. 2 root root 162 Aug 9 21:40 root

drwxr-xr-x. 11 root root 163 Aug 9 21:40 run

lrwxrwxrwx. 1 root root 8 May 11 2019 sbin -> usr/sbin

drwxr-xr-x. 2 root root 6 May 11 2019 srv

dr-xr-xr-x. 13 root root 0 Aug 11 09:58 sys

drwxrwxrwt. 7 root root 145 Aug 9 21:40 tmp

drwxr-xr-x. 12 root root 144 Aug 9 21:40 usr

drwxr-xr-x. 20 root root 262 Aug 9 21:40 var

DockerFile中很多命令都十分相似，我们需要了解他的区别，最好的学习就是对比进行测试查看效果！

实战:Tomcat 镜像

1、准备镜像文件 tomcat压缩包 jdk压缩包

[root@localhost tomcat]# ls
apache-tomcat-8.5.43.tar.gz Dockerfile jdk-8u211-linux-x64.tar.gz read.txt

2、编写dockerfile文件, 官方命名Dockerfile，build会自动寻找这个文件，不需要 -f 指定！

# 引入基础

FROM centos

# 作者信息

MAINTAINER yinxiaodoong<m15010969094@163.com>

# copy文件read.txt到容器的 /usr/local/read.txt 目录下

COPY read.txt /usr/local/read.txt

# 添加jdk tomcat ---> 自动解压

ADD jdk-8u211-linux-x64.tar.gz /usr/local/

ADD apache-tomcat-8.5.43.tar.gz /usr/local/

# 安装 vim 命令

RUN yum install -y vim

# 配置 MYPATH

ENV MYPATH /usr/local/

# 指定进入容器默认路径 /user/local/

WORKDIR $MYPATH

# 配置jdk环境变量

ENV JAVA_HOME /usr/local/jdk1.8.0_211

ENV CLASSPATH $JAVA_HOME/lib/dt.jat:$JAVA_HOME/lib/tools.jar

# 配置tomcat环境变量

ENV CATALINA_HOME /usr/local/apache-tomcat-8.5.43

ENV CATALINA_BASH /usr/local/apache-tomcat-8.5.43

ENV PATH $PATH:$JAVA_HOME/bin:$CATALINA_HOME/lib:$CATALINA_HOME/bin

# 暴露8080端口

EXPOSE 8080

# /usr/local/tomcat/webapps#

# 启动容器时启动tomcat

CMD /usr/local/apache-tomcat-8.5.43/bin/startup.sh && tail -f /usr/local/apache-tomcat-8.5.43/logs/catalina.out

# 构建tomcat镜像

[root@localhost tomcat]# docker build -t mytomcat

[root@localhost tomcat]# docker images

REPOSITORY TAG IMAGE ID CREATED SIZE

mytomcat latest a9707559afa1 8 seconds ago 693MB

centos latest 0d120b6ccaa8 4 days ago 215MB

[root@localhost tomcat]

# docker run -d -p 8081:8080 --name mytomcat--01 -v /home/yinxiaodong/build/tomcat/test:/usr/local/apache-tomcat-8.5.43/webapps/test -v /home/yinxiaodong/build/tomcat/logs:/usr/local/apache-tomcat-8.5.43/logs mytomcat

发布自己的镜像

发布到 dockerHub

地址https://hub.docker.com/ 注册自己的账号

确定自己的账号可以登录

在我们的服务器上提交