Nginx教程+Keepalived高可用

Nginx教程

1. 课程目标
   1. 了解反向代理和负载均衡的概念
   2. 掌握Nginx的安装和使用
   3. 利用Nginx实现负载均衡
2. Nginx相关概念
   1. 反向代理

反向代理（Reverse Proxy）方式是指以代理服务器来接受internet上的连接请求，然后将请求转发给内部网络上的服务器，并将从服务器上得到的结果返回给internet上请求连接的客户端，此时代理服务器对外就表现为一个服务器。

 

1. 1. 负载均衡

负载均衡，英文名称为Load Balance，是指建立在现有网络结构之上，并提供了一种廉价有效透明的方法扩展网络设备和服务器的带宽、增加吞吐量、加强网络数据处理能力、提高网络的灵活性和可用性。其原理就是数据流量分摊到多个服务器上执行，减轻每台服务器的压力，多台服务器共同完成工作任务，从而提高了数据的吞吐量。

 

1. Nginx的安装
   1. 下载nginx

官网：http://nginx.org/

1. 1. 上传并解压nginx

tar -zxvf nginx-1.8.1.tar.gz -C /usr/local/src

1. 1. 编译nginx

#进入到nginx源码目录

cd /usr/local/src nginx-1.8.1

 

#检查安装环境

./configure --prefix=/usr/local/nginx

 

#缺包报错 ./configure: error: C compiler cc is not found

 

#使用YUM安装缺少的包

yum -y install gcc pcre-devel openssl openssl-devel

 

#编译安装

make && make install

1. 配置nginx
   1. 配置反向代理

1. 修改nginx配置文件

server {     listen       80;     server_name  nginx-01.xiaoniu.cn; #172.16.203.101/hello.html location / {     root html;         proxy_pass http://192.168.0.21:8080;     } }

1. 启动tomcat-01上的tomcat

 

3.启动nginx-01上的nginx

./nginx

1. 1. 动静分离

#动态资源 index.jsp

location ~ .*\.(jsp|do|action)$ {     proxy_pass http://tomcat-01.xiaoniu.cn:8080; }

 

#静态资源

location ~ .*\.(html|js|css|gif|jpg|jpeg|png)$ {     expires 3d; }

 

1. 1. 负载均衡

在http这个节下面配置一个叫upstream的，后面的名字可以随意取，但是要和location下的proxy_pass http://后的保持一致。

http {     upstream tomcats {         server 172.16.203.20:8080 weight=1;         server tomcat-02.xiaoniu.cn:8080 weight=1;         server tomcat-02.xiaoniu.cn:8080 weight=1; } location ~ .*\.(jsp|do|action) {     proxy_pass http://tomcats; } }

1. 利用keepalived实现高可靠（HA）
   1. 高可靠概念

HA(High Available), 高可用性集群，是保证业务连续性的有效解决方案，一般有两个或两个以上的节点，且分为活动节点及备用节点。

 

1. 1. 高可靠软件keepalived

keepalive是一款可以实现高可靠的软件，通常部署在2台服务器上，分为一主一备。Keepalived可以对本机上的进程进行检测，一旦Master检测出某个进程出现问题，将自己切换成Backup状态，然后通知另外一个节点切换成Master状态。

1. 1. keepalived安装

下载keepalived官网:http://keepalived.org

 

将keepalived解压到/usr/local/src目录下

tar -zxvf  keepalived-1.3.6.tar.gz -C /usr/local/src

 

进入到/usr/local/src/keepalived-1.3.6目录

cd /usr/local/src/keepalived-1.3.6

 

开始configure

./configure

 

#编译并安装

make && make install

 

1. 1. 将keepalived添加到系统服务中

拷贝执行文件

cp /usr/local/sbin/keepalived /usr/sbin/

将init.d文件拷贝到etc下,加入开机启动项

cp /usr/local/src/keepalived-1.3.6/keepalived/etc/init.d/keepalived /etc/init.d/keepalived

将keepalived文件拷贝到etc下

cp /usr/local/src/keepalived-1.3.6/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

创建keepalived文件夹

mkdir -p /etc/keepalived

将keepalived配置文件拷贝到etc下

cp /usr/local/src/keepalived-1.3.6/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf

添加可执行权限

chmod +x /etc/init.d/keepalived

 

添加keepalived到开机启动

chkconfig --add keepalived

chkconfig keepalived on

 

1. 1. 配置keepalived虚拟IP

 

#MASTER节点

global_defs { } vrrp_instance VI_1 {     state MASTER     interface eth0     virtual_router_id 51     priority 100     advert_int 1     authentication {         auth_type PASS         auth_pass 1111     }     virtual_ipaddress {         10.0.0.10/24     } }

 

#BACKUP节点

global_defs { } vrrp_instance VI_1 {     state BACKUP     interface eth0     virtual_router_id 51     priority 99     advert_int 1     authentication {         auth_type PASS         auth_pass 1111     }     virtual_ipaddress {         10.0.0.10/24     } }

 

#分别启动两台机器上的keepalived

service keepalived start

1. 1. 配置keepalived心跳检查

#MASTER节点

global_defs { }   vrrp_script chk_health {     script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1"     interval 1     weight -2 }   vrrp_instance VI_1 {     state MASTER     interface eth0     virtual_router_id 1     priority 100     advert_int 2     authentication {         auth_type PASS         auth_pass 1111     }       track_script {         chk_health     }       virtual_ipaddress {         10.0.0.10/24     }       notify_master "/usr/local/keepalived/sbin/notify.sh master"     notify_backup "/usr/local/keepalived/sbin/notify.sh backup"     notify_fault "/usr/local/keepalived/sbin/notify.sh fault" }

 

#添加切换通知脚本

vi /usr/local/keepalived/sbin/notify.sh

#!/bin/bash   case "$1" in     master)         /usr/local/nginx/sbin/nginx         exit 0     ;; backup)         /usr/local/nginx/sbin/nginx -s stop         /usr/local/nginx/sbin/nginx         exit 0     ;;     fault)         /usr/local/nginx/sbin/nginx -s stop         exit 0     ;;     *)         echo 'Usage: notify.sh {master|backup|fault}'         exit 1     ;; esac

 

#添加执行权限

chmod +x /usr/local/keepalived/sbin/notify.sh

global_defs { }   vrrp_script chk_health {     script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1"     interval 1     weight -2 }   vrrp_instance VI_1 {     state BACKUP     interface eth0     virtual_router_id 1     priority 99     advert_int 1     authentication {         auth_type PASS         auth_pass 1111     }       track_script {         chk_health     }       virtual_ipaddress {         10.0.0.10/24     }       notify_master "/usr/local/keepalived/sbin/notify.sh master"     notify_backup "/usr/local/keepalived/sbin/notify.sh backup"     notify_fault "/usr/local/keepalived/sbin/notify.sh fault" }

 

#在第二台机器上添加notify.sh脚本

#分别在两台机器上启动keepalived

service keepalived start

chkconfig keepalived on