接下来将编写一个Tomcat的Dockerfile文件，以此构建一个Docker镜像，并基于该镜像启动得到一个Tomcat容器，最后试着在该容器中部署一个测试项目
思路：
- 基于centos镜像，配置一个jdk环境和tomcat环境，并进行环境变量的配置
1 jdk和tomcat下载
自行到网上下载jdk和tomcat的安装包，并上传到自己的服务器的任意目录下，如下图，我这里放在了/opt/web_app/docker_test目录下：
2 编写Dockerfile文件
在jdk和tomcat的安装包的同级目录也就是/opt/web_app/docker_test目录下，编写Dockerfile文件。
注：编写的Dockerfile文件的命名，最好就叫做
Dockerfile，官方推荐的命名方式就是Dockerfile，这么命名，那么在使用docker build构建的时候，就会自动去寻找这个文件，而不需要使用-f去指定了文件！
Dockerfile文件的内容如下：
FROM centos
#声明镜像是谁写的
MAINTAINER suhaha<[email protected]>
#从本地将jdk和tomcat的压缩包，复制到容器的/usr/local目录下去，并自动解压
ADD jdk-8u181-linux-x64.tar.gz /usr/local
ADD apache-tomcat-9.0.54.tar.gz /usr/local
#声明工作目录，并通过WORKDIR命令，切换到工作目录
ENV MYPATH /usr/local
WORKDIR $MYPATH
#环境变量设置，最终将java和tomcat都配置到PATH中
ENV JAVA_HOME /usr/local/jdk1.8.0_181
ENV CLASSPATH $JAVA_HOME/lib/dt.jar:#JAVA_HOME/lib/tools.jar
ENV CATALINA_HOME /usr/local/apache-tomcat-9.0.54
ENV CATALINA_BASE /usr/local/apache-tomcat-9.0.54
ENV PATH $PATH:$JAVA_HOME/bin:$CATALINA_HOME/lib:$CATALINA_HOME/bin
#使用RUN命令，通过yum安装一些日常的常用工具
RUN yum -y install vim
RUN yum -y install net-tools
#对外暴露8080端口
EXPOSE 8080
#执行tomcat的启动命令，并通过tail -f命令，持续跟踪日志输出
CMD /usr/local/apache-tomcat-9.0.54/bin/startup.sh && tail -f /usr/local/apache-tomcat-9.0.54/bin/logs/catalina.out
3 构建
使用如下命令构建
docker build -t my-diy-tomcat .
构建日志如下：
[root@VM-8-5-centos web_app]# docker build -t my-diy-tomcat .
Sending build context to Docker daemon 197.2MB
Step 1/15 : FROM centos
---> 5d0da3dc9764
Step 2/15 : MAINTAINER suhaha<[email protected]>
---> Running in 0b9bccd0217d
Removing intermediate container 0b9bccd0217d
---> a97454015399
Step 3/15 : ADD jdk-8u181-linux-x64.tar.gz /usr/local
---> fc5754e8aa9d
Step 4/15 : ADD apache-tomcat-9.0.54.tar.gz /usr/local
---> b804f9920f02
Step 5/15 : ENV MYPATH /usr/local
---> Running in c69d11a02e1d
Removing intermediate container c69d11a02e1d
---> 65fd2b51b346
Step 6/15 : WORKDIR $MYPATH
---> Running in 89ffdb849840
Removing intermediate container 89ffdb849840
---> ff9bf6740a9f
Step 7/15 : ENV JAVA_HOME /usr/local/jdk1.8.0_181
---> Running in cb3e97f0f5c3
Removing intermediate container cb3e97f0f5c3
---> 86e4466b3027
Step 8/15 : ENV CLASSPATH $JAVA_HOME/lib/dt.jar:#JAVA_HOME/lib/tools.jar
---> Running in f5f0a404edd8
Removing intermediate container f5f0a404edd8
---> 319cf44a7329
Step 9/15 : ENV CATALINA_HOME /usr/local/apache-tomcat-9.0.54
---> Running in 10bd17f04960
Removing intermediate container 10bd17f04960
---> 2ee589f0ba3b
Step 10/15 : ENV CATALINA_BASE /usr/local/apache-tomcat-9.0.54
---> Running in 0d94d8c3b3bd
Removing intermediate container 0d94d8c3b3bd
---> cbc2b4c9bad3
Step 11/15 : ENV PATH $PATH:$JAVA_HOME/bin:$CATALINA_HOME/lib:$CATALINA_HOME/bin
---> Running in 2703da794149
Removing intermediate container 2703da794149
---> af6be7727c8a
Step 12/15 : RUN yum -y install vim
---> Running in a52f4bb0f584
CentOS Linux 8 - AppStream 12 MB/s | 9.3 MB 00:00
CentOS Linux 8 - BaseOS 10 MB/s | 7.5 MB 00:00
CentOS Linux 8 - Extras 5.2 kB/s | 10 kB 00:02
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 2.9 MB/s | 39 kB 00:00
(2/5): vim-filesystem-8.0.1763-15.el8.noarch.rp 3.5 MB/s | 48 kB 00:00
(3/5): vim-enhanced-8.0.1763-15.el8.x86_64.rpm 15 MB/s | 1.4 MB 00:00
(4/5): vim-common-8.0.1763-15.el8.x86_64.rpm 49 MB/s | 6.3 MB 00:00
(5/5): which-2.21-12.el8.x86_64.rpm 468 kB/s | 49 kB 00:00
--------------------------------------------------------------------------------
Total 8.9 MB/s | 7.8 MB 00:00
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) <[email protected]>"
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 a52f4bb0f584
---> 789176169e0a
Step 13/15 : RUN yum -y install net-tools
---> Running in 1c2d4d8e49d9
Last metadata expiration check: 0:00:08 ago on Thu Oct 21 05:37:29 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 600 kB/s | 322 kB 00:00
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 1c2d4d8e49d9
---> 5f0bbc8724b7
Step 14/15 : EXPOSE 8080
---> Running in af27169bf09e
Removing intermediate container af27169bf09e
---> 47dff1593e42
Step 15/15 : CMD /usr/local/apache-tomcat-9.0.54/bin/startup.sh && tail -f /usr/local/apache-tomcat-9.0.54/bin/logs/catalina.out
---> Running in d4bfa4792e38
Removing intermediate container d4bfa4792e38
---> 33a8ac2f0649
Successfully built 33a8ac2f0649
Successfully tagged my-diy-tomcat:latest
构建图示如下：
构建完成之后，使用docker images命令，可以查看到我们构建的镜像：
[root@VM-8-5-centos web_app]# docker images | grep diy
my-diy-tomcat latest 4c3b2ced86e8 About a minute ago 629MB
4 启动镜像
注：启动的时候，注意到我们这里通过-v命令挂载容器内的tomcat的webapps和logs日志目录到本地宿主机上，方便部署项目到容器内，也方便在本地宿主机查看日志。
命令如下：
docker run -it -p 8080:8080 --name zhy_tomcat -v /home/docker/my-diy-tomcat/webapps/test:/usr/local/apache-tomcat-9.0.54/webapps/test -v /home/docker/my-diy-tomcat/logs/:/usr/local/apache-tomcat-9.0.54/logs my-diy-tomcat:latest
图示如下：
由上图可以看到tomcat启动成功
由于我们启动时通过-p 8080:8080命令做了端口映射（即将本地宿主机的8080端口，映射到容器内的8080端口上），因此接下来，测试从网页通过ip:8080端口去连接我们启动的tomcat，如下图，连接成功，证明tomcat容器启动成功，说明我们前面制作的tomcat的Dockerfile文件是没问题的！
5 部署项目tomcat中
接下来测试将一个测试项目test部署到容器中。
注：因为我们在上面启动镜像的时候，已经通过
-v /home/docker/my-diy-tomcat/webapps/test:/usr/local/apache-tomcat-9.0.54/webapps/test命令做了数据卷映射，将本地宿主机的/home/docker/my-diy-tomcat/webapps/test目录，映射到了容器内的/usr/local/apache-tomcat-9.0.54/webapps/test目录。因此接下来我们测试部署项目到tomcat里面时，就不需要进入到容器内去部署了，只需要将项目部署到本地宿主机的/home/docker/my-diy-tomcat/webapps/test即可。
进入到目录下，创建一个WEB-INF目录，并进入到这新建的WEB-INF目录下，并创建一个web.xml文件，文件内容如下：
web.xml内容：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0"
metadata-complete="true">
<display-name>Welcome to zjxl</display-name>
<description>
Welcome to zjxl
</description>
</web-app>
接着回到test目录下，然后新建一个index.jsp文件，内容如下：
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>hello，zjxl</title>
</head>
<body>
zhanghongyan say: Hello World!<br/>
<%
System.out.println("----my test web logs----");
%>
</body>
</html>
如此，测试项目test就算是部署完成了，接着通过网页，去试着访问我们部署的测试项目！如下图，访问成功，项目部署ok！
并且因为在我们的index.jsp中，有如下这么一行代码
System.out.println("----my test web logs----");
所以，我们每在页面访问一次，就会打印此一次日志到tomcat日志中。我们可以在宿主机上直接查看到该日志（因为做了数据卷映射！）：
