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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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