Nginx+keepalived做双机热备加tomcat负载均衡

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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
------------------------------------------------------

　　nginx可以根据客户端IP进行负载均衡，在upstream里设置ip_hash，就可以针对同一个C类地址段中的客户端选择同一个后端服务器，除非那个后端服务器宕了才会换一个。
　　nginx的upstream目前支持的5种方式的分配


1、轮询（默认）
每个请求按时间顺序逐一分配到不同的后端服务器，如果后端服务器down掉，能自动剔除。
upstream backserver {
server 192.168.0.14;
server 192.168.0.15;
}
2、指定权重
指定轮询几率，weight和访问比率成正比，用于后端服务器性能不均的情况。
upstream backserver {
server 192.168.0.14 weight=10;
server 192.168.0.15 weight=10;
}
3、IP绑定 ip_hash
每个请求按访问ip的hash结果分配，这样每个访客固定访问一个后端服务器，可以解决session的问题。
upstream backserver {
ip_hash;
server 192.168.0.14:88;
server 192.168.0.15:80;
}
4、fair（第三方）
按后端服务器的响应时间来分配请求，响应时间短的优先分配。
upstream backserver {
server server1;
server server2;
fair;
}
5、url_hash（第三方）
按访问url的hash结果来分配请求，使每个url定向到同一个后端服务器，后端服务器为缓存时比较有效。
upstream backserver {
server squid1:3128;
server squid2:3128;
hash $request_uri;
hash_method crc32;
}
在需要使用负载均衡的server中增加
proxy_pass http://backserver/;
upstream backserver{
ip_hash;
server 127.0.0.1:9090 down; (down 表示单前的server暂时不参与负载)
server 127.0.0.1:8080 weight=2; (weight 默认为1.weight越大，负载的权重就越大)
server 127.0.0.1:6060;
server 127.0.0.1:7070 backup; (其它所有的非backup机器down或者忙的时候，请求backup机器)
}
max_fails ：允许请求失败的次数默认为1.当超过最大次数时，返回proxy_next_upstream 模块定义的错误
  
　　fail_timeout:max_fails次失败后，暂停的时间