本文直接讲解如何在Docker容器中实战部署一个Web应用程序，关于Docker相关的概念和如何安装Docker请参考相关资料完成。

第一步：工具准备

演示如何在Docker容器中部署一个Java Web应用程序，需要准备的软件工具包括：jre，tomcat和webapp应用。另外，为了实现在容器启动时自动启动webapp，需要编写一个脚本工具完成该工作。

安装jre，请参考：http://www.wikihow.com/Install-Java-on-Linux

安装tomcat，请参考：http://blog.csdn.net/williamcs/article/details/8579957

如何在tomcat中部署webapp，请参考：

http://tomcat.apache.org/tomcat-7.0-doc/deployer-howto.html

http://www.cnblogs.com/zengsong-restService/archive/2013/01/04/2844568.html

jre1.8.0_31.tar.gz   // 可以选择其他版本

apache-tomcat-6.0.35.tar.gz // 可以选择其他版本

MyWeb.war // 自己写一个web应用即可，才发现csdn不允许上传附件

start_tomcat.sh

第二步：制作镜像

通过编写Dockerfile的方式制作镜像。

需要在Dockerfile中完成如下几项工作：

（1）安装jre

（2）安装tomcat，并完成在tomcat中部署web应用的基本配置（为实现此功能：在制作镜像之前直接先完成tomcat的基础配置，然后直接拷贝到镜像中即可）。

（3）对外开发8080端口（具体的端口值可以根据实际Tomcat配置参数为准）。

$mkdir docker

$cd docker

$mkdir webapps

$cp jre1.8.0_31.tar.gz .

$tar xzvf jre1.8.0_31.tar.gz

$cp apache-tomcat-6.0.35.tar.gz

$tar xzvf apache-tomcat-6.0.35.tar.gz

$cp MyWeb.war ./webapps/

$vim apache-tomcat-6.0.35/conf/server.xml

编辑tomcat配置文件：server.xml，在<Host>节点中添加如下配置：<Context path="myweb"docBase="/webapps/MyWeb.war" reloadable="false"workDir="/tomcat_work"/>，配置片段如下所示：

<Host name="localhost"  appBase="webapps"

     unpackWARs="true" autoDeploy="true"

     xmlValidation="false" xmlNamespaceAware="false">

  <!-- SingleSignOn valve, shareauthentication between web applications

       Documentation at:/docs/config/valve.html -->

  <!--

  <Valve className="org.apache.catalina.authenticator.SingleSignOn"/>

  -->

  <!-- Access log processes all example.

       Documentation at:/docs/config/valve.html -->

  <!--

  <ValveclassName="org.apache.catalina.valves.AccessLogValve"directory="logs" 

        prefix="localhost_access_log." suffix=".txt"pattern="common" resolveHosts="false"/>

  -->

  <Contextpath="/myweb"docBase="/webapps/MyWeb.war"reloadable="false"workDir="/tomcat_work"/>

</Host>

$vim start_tomcat.sh

#!/bin/bash

#Date: 2015/02/02

#Desc:

#       Start tomcat with docker containerstart.  

echo "Start Tomcat ..."

# Export java path

export PATH=$PATH:/usr/local/java/bin

# Display container ipaddress

ifconfig

# Start tomcat

bash /usr/local/tomcat/bin/catalina.sh run

注意：启动tomcat时必须通过$TOMCAT_HOME/bin/catalina.sh实现，不能使用$TOMCAT_HOME/bin/startup.sh启动，否则脚本执行后容器立刻就退出了。

编写Dockerfile

#Build java web app container image

FROM docker.cn/docker/ubuntu:14.04

MAINTAINER chenchanghui<nuccch2010.163.com>

#Make java and tomcat install directory

RUN mkdir /usr/local/java

RUN mkdir /usr/local/tomcat

#Copy jre and tomcat into image

ADD jre1.8.0_31 /usr/local/java/

ADD apache-tomcat-6.0.35 /usr/local/tomcat/

ADD start_tomcat.sh start_tomcat.sh

#Expose http port

EXPOSE 8080

创建镜像

$sudo docker build -t=”ubuntu/myweb:tomcat”.

Sendingbuild context to Docker daemon 270.6 MB

Sendingbuild context to Docker daemon

Step 0 :FROM docker.cn/docker/ubuntu:14.04

 ---> b39b81afc8ca

Step 1 :MAINTAINER chenchanghui <nuccch2010.163.com>

 ---> Running in cd9ba3324dae

 ---> ab45c422bdf5

Removingintermediate container cd9ba3324dae

Step 2 :RUN mkdir /usr/local/java

 ---> Running in f640de521691

 ---> bd94048cb633

Removingintermediate container f640de521691

Step 3 :RUN mkdir /usr/local/tomcat

 ---> Running in de4a392ec89d

 ---> 956ac99b8bec

Removingintermediate container de4a392ec89d

Step 4 :ADD jre1.8.0_31 /usr/local/java/

 ---> e3181a61f635

Removingintermediate container b69c147f28fe

Step 5 :ADD apache-tomcat-6.0.35 /usr/local/tomcat/

 ---> 9169a4ab9a80

Removingintermediate container c190162d7a5c

Step 6 :ADD start_tomcat.sh start_tomcat.sh

 ---> cf61f83dc0b0

Removingintermediate container 3f10c2a9e374

Step 7 :EXPOSE 8080

--->abea02c999a2

Removingintermediate container a3841acba123

Successfullybuilt abea02c999a2

第三部：启动容器

webapp通过数据卷挂在到容器中进行部署，不需要拷贝到镜像中。

$sudo docker run -t -i --name tomcat –v /home/$username/docker/webapps:/webapps/

ubuntu/myweb:tomcat /bin/bash/start_tomcat.sh

Start Tomcat ...

eth0     Link encap:Ethernet  HWaddr02:42:ac:11:00:0c 

         inet addr:172.17.0.12 Bcast:0.0.0.0  Mask:255.255.0.0

……..

Feb 02, 2015 1:38:42 PMorg.apache.catalina.core.AprLifecycleListener init

INFO: The APR based Apache Tomcat Nativelibrary which allows optimal performance in production environments was notfound on the java.library.path:/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib

Feb 02, 2015 1:38:42 PMorg.apache.coyote.http11.Http11Protocol init

INFO: Initializing Coyote HTTP/1.1 onhttp-8080

Feb 02, 2015 1:38:42 PMorg.apache.catalina.startup.Catalina load

INFO: Initialization processed in 788 ms

Feb 02, 2015 1:38:42 PMorg.apache.catalina.core.StandardService start

INFO: Starting service Catalina

Feb 02, 2015 1:38:42 PM org.apache.catalina.core.StandardEnginestart

INFO: Starting Servlet Engine: ApacheTomcat/6.0.35

Feb 02, 2015 1:38:42 PMorg.apache.catalina.startup.HostConfig deployDirectory

INFO: Deploying web application directorymanager

Feb 02, 2015 1:38:42 PM org.apache.catalina.startup.HostConfigdeployDirectory

INFO: Deploying web application directorydocs

Feb 02, 2015 1:38:42 PMorg.apache.catalina.startup.HostConfig deployDirectory

INFO: Deploying web application directoryROOT

Feb 02, 2015 1:38:42 PM org.apache.catalina.startup.HostConfigdeployDirectory

INFO: Deploying web application directoryexamples

Feb 02, 2015 1:38:43 PMorg.apache.catalina.startup.HostConfig deployDirectory

INFO: Deploying web application directoryhost-manager

Feb 02, 2015 1:38:43 PM org.apache.coyote.http11.Http11Protocolstart

INFO: Starting Coyote HTTP/1.1 on http-8080

Feb 02, 2015 1:38:43 PMorg.apache.jk.common.ChannelSocket init

INFO: JK: ajp13 listening on /0.0.0.0:8009

Feb 02, 2015 1:38:43 PMorg.apache.jk.server.JkMain start

INFO: Jk running ID=0 time=0/27  config=null

Feb 02, 2015 1:38:43 PMorg.apache.catalina.startup.Catalina start

INFO: Server startup in 842 ms

如日志所示，Docker容器已经启动，并且其中安装的tomcat已经成功启动。

访问：http://172.17.0.12:8080/myweb/，Everything is ok！

小技巧：启动容器时带参数-t -i和不带参数的区别：带参数-t -i时可以通过Ctrl+C停止容器运行，不带参数-t -i启动时，停止容器只能通过命令：$sudo docker stop $containerid实现。