Load Balancing with Tomcat + Nginx

1. Introduction to Tomcat

• Tomcat is a free and open source Serlvet container, which is a core project in the Jakarta project of the Apache Foundation;
• Developed by Apache, Sun and other companies and individuals.
• Unlike traditional desktop applications, an application in Tomcat is a WAR (Web Archive) file.
• WAR is a Web application format proposed by Sun, and similar to JAR, it is also a compressed package of many files.

2. Install the Tomcat service

Ready to work:

CPU name	operating system	IP address
Tomcat-A	CentOS7.x	192.168.1.1

1. Install and configure Tomcat

1) Install JDK and configure JAVA environment:

[root@Tomcat-A ~]# ls
anaconda-ks.cfg  apache-tomcat-8.5.16.tar.gz  jdk-8u91-linux-x64.tar.gz
[root@Tomcat-A ~]# tar zxf jdk-8u91-linux-x64.tar.gz
[root@Tomcat-A ~]# mv jdk1.8.0_91/ /usr/local/java									# 移动,并重命名
[root@Tomcat-A ~]# cat <<END >> /etc/profile										# 配置环境变量
export JAVA_HOME=/usr/local/java
export PATH=$PATH:/usr/local/java/bin
END
[root@Tomcat-A ~]# source /etc/profile
[root@Tomcat-A ~]# java -version													# 查看 Java 版本号

2) Install the Tomcat software:

[root@Tomcat-A ~]# tar zxf apache-tomcat-8.5.16.tar.gz
[root@Tomcat-A ~]# mv apache-tomcat-8.5.16 /usr/local/tomcat8       				# 移动,并重命名
[root@Tomcat-A ~]# /usr/local/tomcat8/bin/startup.sh                				# 启动 Tomcat
[root@Tomcat-A ~]# netstat -anpt | grep 8080  										# Tomcat 的工作端口
[root@Tomcat-A ~]# netstat -anpt | grep java  										# 查看 Java 端口号

annotation:

• Port 8005: The port number that needs to be used when shutdown.shclosing Tomcat. If this port is not activated, Tomcat cannot be shutdownclosed with the command.
• Port 8009: It is the port that Tomcat is responsible for establishing connections with other HTTP servers, such as Nginx and Apache to communicate with each other. (AJP/1.3 protocol)
• Port 8080: The port used for HTTP access. (HTTP/1.1 protocol)

2. Verify

3. Configure the Java Web Directory

[root@Tomcat-A ~]# mkdir -p /web/tomcat
[root@Tomcat-A ~]# echo "192.168.1.1:Tomcat-A" > /web/tomcat/index.jsp

4. Modify the Tomcat main configuration file

[root@Tomcat-A ~]# vim /usr/local/tomcat8/conf/server.xml
在148-151行添加：
<Context docBase="/web/tomcat" path="" reloadable="false">
</Context>

annotation:

• unpackWARs="true": Set to automatically identify war package.
• autoDeploy="true": Enable automatic deployment.
• Context docBase="/web/tomcat": The root directory of the web page.
• path="": Set the web page; it is equivalent to the Location in Nginx.
• reloadble="false": The web application will not be automatically reloaded. If set to , trueit will be automatically reloaded when the file is changed.

Restart the Tomcat service

[root@Tomcat-A ~]# /usr/local/tomcat8/bin/shutdown.sh

[root@Tomcat-A ~]# /usr/local/tomcat8/bin/startup.sh

verify:

3. Use Tomcat + Nginx to achieve load balancing

Ready to work:

CPU name	operating system	IP address
Tomcat-A	CentOS7.x	192.168.1.1
Tomcat-B	CentOS7.x	192.168.1.2
Nginx-Server	CentOS7.x	192.168.1.3

Notice:

• Tomcat-A can use the above experimental materials;
• Tomcat-B has the same steps as Tomcat-A, but the pages should be separated to facilitate testing;

1. Deploy Nginx server

1) Install Nginx service

[root@Nginx-Server ~]# yum -y install pcre-devel zlib-devel popt-devel openssl-devel openssl
[root@Nginx-Server ~]# wget http://www.nginx.org/download/nginx-1.18.0.tar.gz
[root@Nginx-Server ~]# ls
anaconda-ks.cfg  nginx-1.18.0.tar.gz
[root@Nginx-Server ~]# tar zxf nginx-1.18.0.tar.gz -C /usr/src/
[root@Nginx-Server ~]# cd /usr/src/nginx-1.18.0/
[root@Nginx-Server nginx-1.18.0]# useradd -M -s /sbin/nologin nginx
[root@Nginx-Server nginx-1.18.0]# ./configure \
--prefix=/usr/local/nginx \
--user=nginx \
--group=nginx \
--with-http_stub_status_module && make && make install
[root@Nginx-Server nginx-1.18.0]# ln -s /usr/local/nginx/sbin/nginx /usr/local/sbin/

2) Configure Nginx main configuration file

[root@Nginx-Server ~]# vim /usr/local/nginx/conf/nginx.conf
在 32 行增加：
upstream tomcat_server {
    
    
    server 192.168.1.1:8080 weight=1;
    server 192.168.1.2:8080 weight=1;
}
在 49 行添加：
proxy_pass http://tomcat_server;

[root@Nginx-Server ~]# nginx -t													# 检查 Nginx 配置文件是否正确
[root@Nginx-Server ~]# nginx													# 启用 Nginx 服务
[root@Nginx-Server ~]# ps aux | grep nginx										# 查看 Nginx 服务进程
[root@Nginx-Server ~]# netstat -anpt | grep nginx								# 查看 Nginx 端口号和进程号

2. Verify

Use a browser to access the IP address of the Nginx server:

keep refreshing the page and observe the page changes:

use the script to view the effect:

[root@Nginx-Server ~]# for i in $(seq 10);do curl http://192.168.1.3;done