Keepalived + Nginx + Tomcat 的高可用负载均衡架构
如下图：为典型的Tomcat服务多实例部署的架构图
（1）用户通过域名请求到DNS，由DNS解析域名后返回对应的IP地址，该IP及为Keepalived映射服务器的虚拟IP
（2）通过该虚拟IP访问到对应的负载均衡器（Nginx），这里Nginx部署两个，然后通过Keepalived来保证NG的高可用，正常情况下由Keepalived-M将虚拟IP映射转发至Nginx-M，
如果Nginx-M出现故障，此时Keepalived会切换至Keepalived-S开始工作，从而保证了NG的单点故障问题。
（3）通过Nginx负载均衡器，将请求路由到对应的Tomcat服务
开始搭建Keepalived + Nginx + Tomcat 的高可用负载均衡架构
服务器准备两台：192.168.1.146、192.168.1.48
安装依赖包yum install -y gcc gcc-c++ ncurses-devel perl pcre pcre-devel openssl openssl-devel zlib make
安装nginx+tomcat
安装nginx
如果yum已安装pcre插件可以不用安装
[root@nginx ~]# useradd nginx -s /sbin/nologin
[root@nginx opt]# tar zxf pcre-8.34.tar.gz
[root@nginx opt]# cd pcre-8.34
[root@nginx pcre-8.34]# ./configure
[root@nginx pcre-8.34]# make && make install
[root@nginx opt]# tar zxf tengine-1.5.1.tar.gz
[root@nginx opt]# cd tengine-1.5.1
[root@nginx tengine-1.5.1]# ./configure --user=nginx --group=nginx --prefix=/usr/local/nginx --with-http_stub_status_module --with-http_ssl_module
[root@nginx tengine-1.5.1]# make && make install(1)修改配置文件
[root@nginx ~]# mv /usr/local/nginx/conf/nginx.conf /usr/local/nginx/conf/nginx.conf.bak
[root@nginx ~]# vi /usr/local/nginx/conf/nginx.conf添加以下配置
user nginx nginx;
worker_processes auto;
worker_rlimit_nofile 65535;
error_log /var/log/www/error.log;
#pid logs/nginx.pid;
events {
use epoll;
worker_connections 51200;
}
http {
include mime.types;
default_type application/octet-stream;
log_format main ‘$remote_addr - $remote_user [$time_local] "$request"‘
‘$status $body_bytes_sent "$http_referer" ‘
‘"$http_user_agent" "$http_x_forwarded_for"‘;
server_info off;
server_tag off;
server_name_in_redirect off;
access_log /var/log/www/access.log main;
client_max_body_size 20m;
client_header_buffer_size 16k;
large_client_header_buffers 4 16k;
sendfile on;
tcp_nopush on;
keepalive_timeout 65;
server_tokens on;
gzip on;
gzip_min_length 1k;
gzip_buffers 4 16k;
gzip_proxied any;
gzip_http_version 1.1;
gzip_comp_level 3;
gzip_types text/plain application/x-javascript text/css application/xml;
gzip_vary on;
upstream www {
#ip_hash;
server 192.168.1.146:8080;
server 192.168.1.148:8080;
}
server {
listen 80;
server_name localhost;
location / {
root html;
index index.html index.htm;
proxy_pass http://www;
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
client_max_body_size 10m;
client_body_buffer_size 128k;
proxy_connect_timeout 90;
proxy_send_timeout 90;
proxy_read_timeout 90;
proxy_buffer_size 4k;
proxy_buffers 4 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;
}
}
}安装tomcat
安装jdk，然后解压tomcat到指定路径
[root@test1 date]# rpm -ivh jdk-7u79-linux-x64.rpm
[root@test1 date]# tar zxf apache-tomcat-7.0.85.tar.gz
[root@test1 date]# mv apache-tomcat-7.0.85 /usr/local/tomcat安装keepalived
[root@test1 date]#yum -y install keepalived
[root@test1 date]#mv /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@test1 date]#vi /etc/keepalived/keepalived.conf修改配置文件keepalived.conf
#全局配置
global_defs {
router_id LVS_DEVEL
}
#执行脚本配置
vrrp_script check_nginx_status {
script "/etc/keepalived/check_nginx_status.sh"
interval 2
weight 2
}
#keeplived实例配置
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 88
priority 99 #优先级
advert_int 1
nopreempt
authentication {
auth_type PASS
auth_pass Chefu88
}
track_script {
check_nginx_status
}
#虚拟ip
virtual_ipaddress {
192.168.1.140
}执行脚本配置check_nginx_status.sh
检测到nginx进程，wc -l统计后，如果为0，就说明ps查不到nginx进程，然后等待3秒，自动启动nginx，
如果重新启动后，已然找不到nginx进程才会关闭keep，然后当keep关闭后，vip就转移到另一台机器
#!/bin/bash
#keepalived check nginx status scripts
prog=nginx
prog_num=`ps -C $prog --no-header | wc -l`
if [ $prog_num -eq 0 ];then
/usr/local/nginx/sbin/nginx
sleep 3s
prog_num=`ps -C $prog --no-header | wc -l`
if [ $prog_num -eq 0 ];then
killall keepalived
fi
fi查看keepalived切换的效果，如虚拟ip在192.168.1.146上，停止146的keeplived，然后再次查看虚拟ip是否切换到192.168.1.148上，访问虚拟ip：192.168.1.140，可以查看到访问的是主keepalived服务器的tomcat
原文地址：http://blog.51cto.com/690156297/2095779
