Nginx+keepalived做双机热备加tomcat负载均衡

环境说明：

nginx1:192.168.2.47
nginx2:192.168.2.48
tomcat1:192.168.2.49
tomcat2:192.168.2.50
vip:192.168.2.51

一.Nginx配置
1.安装Nginx所需pcre库
wget ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-8.10.tar.gz

tar -zxvf pcre-8.10.tar.gz
cd pcre-8.10
./configure
make
make install

2.安装Nginx
wget http://nginx.org/download/nginx-0.8.52.tar.gz

groupadd www
useradd -g www www
tar zxvf nginx-0.8.52.tar.gz
cd nginx-0.8.52/
./configure --user=www --group=www --prefix=/usr/local/nginx --with-http_stub_status_module --with-http_ssl_module
make
make install

注：如果出现以下错误

./configure: error: SSL modules require the OpenSSL library.
Centos需要安装openssl-devel
Ubuntu则需要安装:sudo apt-get install libssl-dev

3.修改配置文件为以下内容：

user  www www;
worker_processes 2;
pid        logs/nginx.pid;
worker_rlimit_nofile 51200;
 
events
{
 use epoll;
 worker_connections 51200;
}
 
http
{
 include       mime.types;
 default_type  application/octet-stream;
 keepalive_timeout 120;
 server_tokens off;
 send_timeout 60;
 tcp_nodelay on;
 
 upstream  tomcats  {
 server 192.168.2.50:8080;
 server 192.168.2.49:8080;
 #ip_hash;       #在没有做共享session的情况下ip_hash可以解决session问题
 
 }
 
 server
 {
 listen  80;
 server_name  192.168.2.48;
 
 location / {
 proxy_pass        http://tomcats;
 proxy_set_header   Host             $host;
 proxy_set_header   X-Real-IP        $remote_addr;
 proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
 }
 
 log_format access_log  '$remote_addr - $remote_user [$time_local] $request '
 '"$status" $body_bytes_sent "$http_referer" '
 '"$http_user_agent" "$http_x_forwarded_for"';
 access_log  /usr/local/nginx/logs/access.log  access_log;
 }
 
}

4.测试配置文件

/usr/local/nginx/sbin/nginx -t

如果出现以下情况

/usr/local/nginx/sbin/nginx: error while loading shared libraries: libpcre.so.0: or directory

解决方法：

sudo ln -s /usr/local/lib/libpcre.so.0 /usr/lib/libpcre.so.0

/usr/local/nginx/sbin/nginx -t
显示以下信息为正确的

the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
configuration file /usr/local/nginx/conf/nginx.conf test is successful

5.优化内核参数
vim /etc/sysctl.conf在最后添加

net.ipv4.tcp_max_syn_backlog = 65536
net.core.netdev_max_backlog = 32768
net.core.somaxconn = 32768
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_syn_retries = 2
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_max_orphans = 3276800
net.ipv4.ip_local_port_range = 1024  65535

保存退出后执行

sysctl -p

6.切割Nginx日志脚本

#!/bin/bash
PATH_LOGS="/usr/local/nginx/logs"
YEAR=`date -d "-1 days" +"%Y"`
MONTH=`date -d "-1 days" +"%m"`
mkdir -p $PATH_LOGS/$YEAR/$MONTH
mv $PATH_LOGS/access.log $PATH_LOGS/$YEAR/$MONTH/access_$(date -d "-1 days" +"%Y%m%d").log
kill -USR1 `cat $PATH_LOGS/nginx.pid`

把该脚本加到crontab每天00点执行
注：备机的Nginx和以上安装步骤一样

二.安装配置Keepalived
1.下载所需要的软件
wget http://keepalived.org/software/keepalived-1.1.19.tar.gz
wget http://rpm5.org/files/popt/popt-1.16.tar.gz
2.安装popt
编译keepalived时需要popt，否则会报以下错误：

configure: error: Popt libraries is required

tar -zxvf popt-1.16.tar.gz
cd popt-1.16
./configure
make
make install

3.安装keepalived

tar -zxvf keepalived-1.1.19.tar.gz
cd keepalived-1.1.19
./configure --prefix=/usr/local/keepalived
make
make install

4.修改配置文件为以下内容:

vim /usr/local/keepalived/etc/keepalived/keepalived.conf

! Configuration File for keepalived
 
global_defs {
 router_id LVS_DEVEL
}
vrrp_script Monitor_Nginx {
 script "/root/scripts/monitor_nginx.sh" #根据自己的实际路径放置monitor_nginx.sh    
 interval 2
 weight 2
}
vrrp_instance VI_1 {
 state MASTER
 interface eth0
 virtual_router_id 51
 priority 100
 advert_int 1
 authentication {
 auth_type PASS
 auth_pass 1234
}
 track_script {
 Monitor_Nginx
}
 virtual_ipaddress {
 192.168.2.51
 }
}

注：monitor_nginx.sh为监控nginx进程的脚本,内容如下

#!/bin/bash
if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]
then
 /usr/local/nginx/sbin/nginx
 sleep 5
 if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]
 then
 killall keepalived
 fi
fi

5.启动keepalived

/usr/local/keepalived/sbin/keepalived -D -f /usr/local/keepalived/etc/keepalived/keepalived.conf

注:备机的keepalived的安装和上面一样，只要把配置文件改为以下(把MASTER改为BACKUP)

! Configuration File for keepalived
 
global_defs {
 router_id LVS_DEVEL
}
vrrp_script Monitor_Nginx {
 script "/root/scripts/monitor_nginx.sh"
 interval 2
 weight 2
}
vrrp_instance VI_1 {
 state BACKUP            #改为BACKUP
 interface eth0
 virtual_router_id 51
 priority 100            #比MASTER数值要低
 advert_int 1
 authentication {
 auth_type PASS
 auth_pass 1234
}
 track_script {
 Monitor_Nginx
}
 virtual_ipaddress {
 192.168.2.51
 }
}

三．测试步骤

1．    访问VIP看是否能够正常访问后端的tomcat
2．    停止其中一个tomcat看是否能将访问转到另一台上
3．    停止两台nginx上任何一个nginx进程看监控进程脚本是否会自动启动nginx
4．    停止任何一台nginx上的keepalived进程看另一台是否接管vip
比如停止Master上的keepalived,例如如下killall keepalived,查看BACKUP机器是否已经接管，如果BACKUP接管后，BACKUP机器日志会是出下情况
tail  /var/log/syslog

Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.2.51

MASTER机器上日志会显示

Keepalived_vrrp: Terminating VRRP child process on signal
Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.

现在把MASTER上的Keepalived重新启动，会看到MASTER重新接管VIP，并对外提供服务，BACKUP仍旧回到BACKUP STATE,如果不是这种情况，请检查配置文件和步骤.

现在的BACKUP日志如下：

Keepalived_vrrp: VRRP_Instance(VI_1) Received higher prio advert
Keepalived_vrrp: VRRP_Instance(VI_1) Entering BACKUP STATE
Keepalived_vrrp: VRRP_Instance(VI_1) removing protocol VIPs.

Master日志如下：

Keepalived_vrrp: VRRP_Script(Monitor_Nginx) succeeded
Keepalived_vrrp: VRRP_Instance(VI_1) Transition to MASTER STATE
Keepalived_vrrp: VRRP_Instance(VI_1) Entering MASTER STATE
Keepalived_vrrp: VRRP_Instance(VI_1) setting protocol VIPs.
Keepalived_vrrp: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for 192.168.2.51

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