使用nginx实现负载均衡，使用Keepalived搭建高可用nginx集群
Nginx安装步骤
1、前置环境安装 安装gcc
yum install -y gcc-c++
安装pcre 是用正则表达式库，http需要使用pcre解析正则表达式
yum install -y pcre prce-devel
安装zlib zlib提供多种压缩方式，nginx使用的zlib对http内容进行压缩
yum install -y zlib zlib-devel
安装openSSL 安全套接字层密码库
yum install -y openssl opensll-devel
2、 安装Nginx 下载nginx安装包
wget http://nginx.org/download/nginx-1.9.14.tar.gz
解压nginx安装包
tar -zxvf nginx-1.9.14.tar.gz
cd nginx-1.9.14 进入nginx解压文件
./configure --prefix=/usr/local/nginx 运行解压文件下的configure文件安装
--prefix安装文件前缀，文件安装目录下
make 编译 （make的过程是把各种语言写的源码文件，变成可执行文件和各种库文件）
make install 安装 （make install是把这些编译出来的可执行文件和库文件复制到合适的地方）
启动nginx
安装目录下/sbin/nginx 启动nginx
安装目录下/sbin/nginx -s reload 重启nginx
安装目录下/sbin/nginx -s stop 关闭nginx
配置nginx 安装目录下/conf/nginx/conf
http {
include mime.types;
default_type application/octet-stream;
sendfile on;
#tcp_nopush on;
#keepalive_timeout 0;
keepalive_timeout 65;
#gzip on;
//配置负载均衡点，指定的ip集合负载均衡提高服务
upstream tomcats{
server 118.89.29.12:88 weight=2;
server 118.89.29.12:90;
}
server {
//监听端口
listen 80;
//服务器名称
server_name localhost;
location / {
proxy_pass http://tomcats;//反向代理，由该指定的ip提高服务
index index.html index.htm;//初始化界面
}
}
keepalived:1 定时检查nginx是否在使用 2 虚拟出一个ip地址共多台nginx服务器使用，达到高可用作用 一台为master，一台为backup 一台宕机另一台顶上
基于centos7.3安装keepalived keepalived源码文件下载：http://www.keepalived.org/software/keepalived-1.2.20.tar.gz
wget http://www.keepalived.org/software/keepalived-1.2.20.tar.gz
1 解压文件
tar -zxvf keepalived-1.2.20.tar.gz
2 进入解压文件
cd keepalived-1.2.20
3 执行文件
./configure --prefix=/usr/local/keepalived/ 指定安装程序位置
4 编译与安装
make && make install
安装完成，进行相关配置 创建文件
mkdir /etc/keepalived/
拷贝文件：
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/keepalived
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/keepalived
编写 Nginx 状态检测脚本
/etc/keepalived/nginx_check.sh
!/bin/bash
A=`ps -C nginx ὀ~Sno-header |wc -l`
if [ $A -eq 0 ];then
/usr/local/nginx/sbin/nginx #nginx启动文件的位置
sleep 2
if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
killall keepalived
fi
fi
修改/etc/keepalived/keepalived.conf
global_defs {
router_id 118.89.29.12
}
vrrp_script chk_nginx {
script "/etc/keepalived/nginx_check.sh"
interval 2
weight -20
}
vrrp_instance VI_1 {
state MASTER #主nginx配置master ，从nginx服务器配置为backup
interface eth0#网卡位置，eth0/eth1/eth2
virtual_router_id 11 #任意给，主从nginx服务器该值要保持一致
mcast_src_ip 118.89.29.12 #本机ip地址，公网地址
priority 100 #优先级
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_nginx #nginx检测脚本信息
}
virtual_ipaddress {
118.89.29.12 #keepalived虚拟出来的ip地址，必须同一网段下有效
}
}
keepalived命令
启动keepalived
systemctl start keepalived
关闭keepalived
systemctl stop keepalived
重启keepalived
systemctl restart keepalived
设置为开机自启
systemctl enable keepalived