系统环境：Centos 7.6
最近研究学习了下Docker，借此机会用docker来搭建实现了下tomcat集群，以此加深对docker的认识。以此文记录相关的步骤细节及心得。
1、安装docker
yum install -y yum-utils device-mapper-persistent-data lvm2 epel-release
yum install -y docker
systemctl start docker
2、创建日志、配置文件目录
提前创建相应的日志文件目录和配置文件目录，用于挂载到相应的容器目录中。
[root@localhost ~]# mkdir /data/tomcatA/{catalina_logs,app_logs,conf,bin} -pv
mkdir: created directory `/data'
mkdir: created directory `/data/test'
mkdir: created directory `/data/test/catalina_logs'
mkdir: created directory `/data/test/app_logs'
mkdir: created directory `/data/test/conf'
mkdir: created directory `/data/test/bin'
[root@localhost ~]# mkdir /data/tomcatB/{catalina_logs,app_logs,conf,bin} -pv
mkdir: created directory ‘/data/tomcatB’
mkdir: created directory ‘/data/tomcatB/catalina_logs’
mkdir: created directory ‘/data/tomcatB/app_logs’
mkdir: created directory ‘/data/tomcatB/conf’
mkdir: created directory ‘/data/tomcatB/bin’
3、创建应用目录
用于存放相应的tomcat应用项目。
[root@localhost ~]# mkdir /usr/local/apps/{tomcatA,tomcatB} -pv
[root@localhost ~]# vim /usr/local/apps/tomcatA/index.jsp
<%@ page language="java" %>
<html>
<head><title>TomcatA</title></head>
<body>
<h1><font color="red">TomcatA.example.com</h1>
<table align="centre" border="1">
<tr>
<td>Session ID</td>
<% session.setAttribute("example.com","example.com"); %>
<td><%= session.getId() %></td>
</tr>
<tr>
<td>Created on</td>
<td><%= session.getCreationTime() %></td>
</tr>
</table>
</body>
</html>
[root@localhost ~]# vim /usr/local/apps/tomcatB/index.jsp
<%@ page language="java" %>
<html>
<head><title>TomcatB</title></head>
<body>
<h1><font color="green">TomcatB.example.com</h1>
<table align="centre" border="1">
<tr>
<td>Session ID</td>
<% session.setAttribute("example.com","example.com"); %>
<td><%= session.getId() %></td>
</tr>
<tr>
<td>Created on</td>
<td><%= session.getCreationTime() %></td>
</tr>
</table>
</body>
</html>
[root@localhost ~]# mkdir /usr/local/apps/tomcatA/WEB-INF/
[root@localhost ~]# mkdir /usr/local/apps/tomcatB/WEB-INF/
[root@localhost ~]# vim /usr/local/apps/tomcatA/WEB-INF/web.xml
<?xml version="1.0" encoding="UTF-8"?>
<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<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_3_1.xsd"
version="3.1"
metadata-complete="true">
<distributable/> #分别在tomcatA、tomcatB的应用目录的WEB-INF的web.xml中添加此参数块。
<display-name>Welcome to Tomcat</display-name>
<description>
Welcome to Tomcat
</description>
</web-app>
4、复制创建相应的tomcat 配置文件
[root@localhost ~]# docker pull tomcat
#临时起一个tomcat容器，复制相应的配置文件，docker run 命令的--rm 选项可以在容器退出的时候直接删除容器
[root@localhost ~]# docker run --name tomcat-test --rm -it docker.io/tomcat /bin/bash
root@79b965c5e312:/usr/local/tomcat#
#新起一个ssh终端复制相应的配置文件
[root@localhost ~]# docker cp tomcat-test:/usr/local/tomcat/conf/server.xml /data/tomcatA/conf/
[root@localhost ~]# docker cp tomcat-test:/usr/local/tomcat/conf/server.xml /data/tomcatB/conf/
[root@localhost ~]# docker cp tomcat-test:/usr/local/tomcat/bin/catalina.sh /data/tomcatA/bin/
[root@localhost ~]# docker cp tomcat-test:/usr/local/tomcat/bin/catalina.sh /data/tomcatB/bin/
5、配置运行Docker tomcat容器
调整docker tomcat的配置文件：
[root@localhost ~]# vim /data/tomcatA/bin/catalina.sh
JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms512m -Xmx512m -Duser.timezone=Asia/Shanghai"
[root@localhost ~]# vim /data/tomcatB/bin/catalina.sh
JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms512m -Xmx512m -Duser.timezone=Asia/Shanghai"
[root@localhost ~]# vim /data/tomcatA/conf/server.xml
....
<Host name="localhost" appBase="webapps"
unpackWARs="true" autoDeploy="true">
<Context path="" docBase="tomcatA" reloadable="false" /> #指定项目包的路径
<!-- SingleSignOn valve, share authentication 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
Note: The pattern used is equivalent to using pattern="common" -->
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="localhost_access_log" suffix=".txt"
pattern="%h %l %u %t "%r" %s %b" />
</Host>
.......
[root@localhost ~]# vim /data/tomcatB/conf/server.xml
....
<Host name="localhost" appBase="webapps"
unpackWARs="true" autoDeploy="true">
<Context path="" docBase="tomcatB" reloadable="false" /> #指定项目包的路径
<!-- SingleSignOn valve, share authentication 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
Note: The pattern used is equivalent to using pattern="common" -->
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="localhost_access_log" suffix=".txt"
pattern="%h %l %u %t "%r" %s %b" />
</Host>
.......
#docker run 参数选项解释
#--memory:指定容器运行的内存大小
#-d:以后台方式运行容器
#-v:指定挂载到容器中的目录，格式：宿主机目录:容器中的目录
#-p:指定容器映射的端口，格式：宿主机端口:容器端口
[root@localhost ~]# docker run -p 8080:8080 --name tomcatA --memory 512M -d -v /data/tomcatA/catalina_logs/:/usr/local/tomcat/logs/ -v /data/tomcatA/app_logs/:/usr/local/logs -v /usr/local/apps/:/usr/local/tomcat/webapps/ -v /data/tomcatA/conf/server.xml:/usr/local/tomcat/conf/server.xml -v /data/tomcatA/bin/catalina.sh:/usr/local/tomcat/bin/catalina.sh docker.io/tomcat
[root@localhost ~]# docker run -p 8081:8080 --name tomcatB --memory 512M -d -v /data/tomcatB/catalina_logs/:/usr/local/tomcat/logs/ -v /data/tomcatB/app_logs/:/usr/local/logs -v /usr/local/apps/:/usr/local/tomcat/webapps/ -v /data/tomcatB/conf/server.xml:/usr/local/tomcat/conf/server.xml -v /data/tomcatB/bin/catalina.sh:/usr/local/tomcat/bin/catalina.sh docker.io/tomcat
[root@localhost ~]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
2754623ea1de docker.io/tomcat "catalina.sh run" 2 minutes ago Up 37 seconds 0.0.0.0:8080->8080/tcp tomcatA
3ab68e00ebdc docker.io/tomcat "catalina.sh run" 2 minutes ago Up 51 seconds 0.0.0.0:8081->8080/tcp tomcatB
6、配置tomcat集群
#修改相应tomcat的配置信息，在host配置段中添加cluster配置段
[root@localhost ~]# vim /data/tomcatA/conf/server.xml
<Host name="localhost" appBase="webapps"
unpackWARs="true" autoDeploy="true">
<Context path="" docBase="tomcatA" reloadable="false" />
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="localhost_access_log" suffix=".txt"
pattern="%h %l %u %t "%r" %s %b" />
<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"
channelSendOptions="8">
<Manager className="org.apache.catalina.ha.session.DeltaManager"
expireSessionsOnShutdown="false"
notifyListenersOnReplication="true"/>
<Channel className="org.apache.catalina.tribes.group.GroupChannel">
<Membership className="org.apache.catalina.tribes.membership.McastService"
address="228.0.0.4"
port="45565"
frequency="50"
dropTime="3000"/>
<Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"
address="auto"
port="4001"
autoBind="100"
selectorTimeout="5000"
maxThreads="10"/>
<Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
<Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>
</Sender>
<Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>
<Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatchInterceptor"/>
</Channel>
<Valve className="org.apache.catalina.ha.tcp.ReplicationValve"
filter=""/>
<Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>
<ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>
</Cluster>
</Host>
[root@localhost ~]# vim /data/tomcatB/conf/server.xml
<Host name="localhost" appBase="webapps"
unpackWARs="true" autoDeploy="true">
<Context path="" docBase="tomcatB" reloadable="false" />
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
prefix="localhost_access_log" suffix=".txt"
pattern="%h %l %u %t "%r" %s %b" />
<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"
channelSendOptions="8">
<Manager className="org.apache.catalina.ha.session.DeltaManager"
expireSessionsOnShutdown="false"
notifyListenersOnReplication="true"/>
<Channel className="org.apache.catalina.tribes.group.GroupChannel">
<Membership className="org.apache.catalina.tribes.membership.McastService"
address="228.0.0.4"
port="45565"
frequency="50"
dropTime="3000"/>
<Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"
address="auto"
port="4001"
autoBind="100"
selectorTimeout="5000"
maxThreads="10"/>
<Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
<Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>
</Sender>
<Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>
<Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatchInterceptor"/>
</Channel>
<Valve className="org.apache.catalina.ha.tcp.ReplicationValve"
filter=""/>
<Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>
<ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>
</Cluster>
</Host>
#重启Tomcat容器
[root@localhost ~]# docker restart tomcatA
tomcatA
[root@localhost ~]# docker restart tomcatB
tomcatB
7、验证docker部署的tomcat集群
[root@localhost ~]# yum install -y nginx
#查看相应的容器所使用的IP信息，docker inspect 可以查看当前运行的容器的相关信息，包括挂载的目录路径，网络IP信息等，--format可指定显示相匹配的json信息
[root@localhost ~]# docker inspect --format '{{.NetworkSettings}}' tomcatA
{ f602619757b50d5eefb76e816511589d11051e2414e0a30aaf2fa0db07b4d062 172.17.42.1 0 false 172.17.0.8 16 0 02:42:ac:11:00:08 17f8cc9318b27eac597aafdd3277209bb71b6b26bed7bae5ce684eddf14f9f6f map[] map[8080/tcp:[{0.0.0.0 8080}]] /var/run/docker/netns/2cfd1be49d4e [] []}
[root@localhost ~]# docker inspect --format '{{.NetworkSettings}}' tomcatB
{ ebb88aaba5eb3fecd1da103269fbb91ea52f5e07eecb9cc6823d2305a152dde6 172.17.42.1 0 false 172.17.0.6 16 0 02:42:ac:11:00:06 17f8cc9318b27eac597aafdd3277209bb71b6b26bed7bae5ce684eddf14f9f6f map[] map[8080/tcp:[{0.0.0.0 8081}]] /var/run/docker/netns/f34a7eb231d6 [] []}
#docker run 的--ip 指定容器IP的选项，需要在用户自建的docker网络才能生效，此处我用的是默认的docker网络，因此无法指定相应的容器IP。
[root@localhost ~]# vim /etc/nginx/nginx.conf
#在http配置段中添加下述配置
upstream tomcat {
server 172.17.0.8:8080 max_fails=1 fail_timeout=3s;
server 172.17.0.6:8080 max_fails=1 fail_timeout=3s;
}
server {
listen 80;
server_name test.tomcat.com
location / {
proxy_pass http://tomcat;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
#配置防火墙放开80端口的访问，注意docker需要系统防火墙来配置相应的转发规则，所以不能把防火墙停用。
[root@localhost ~]# firewall-cmd --zone=public --add-port=80/tcp --permanent
[root@localhost ~]# firewall-cmd --reload
[root@localhost ~]# firewall-cmd --list-all
#启动nginx
[root@localhost ~]# service nginx configtest
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
[root@localhost ~]# service nginx start
Starting nginx: [ OK ]
测试访问页面：
image.png
image.png
