Nginx+keepalived安装

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1. Nginx相关概念1.1. 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。

1.2. 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。

2. Nginx的安装2.1. 下载nginx官网：http://nginx.org/
2.2. 上传并解压nginxtar -zxvf nginx-1.8.1.tar.gz -C /usr/local/src
2.3. 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,并指定将来要安装的路径
./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

安装完后测试是否正常：
/usr/loca/nginx/sbin/nginx
查看端口是否有ngnix进程监听
netstat -ntlp | grep 80

3. 配置nginx3.1. 配置反向代理1.修改nginx配置文件（/usr/local/nginx/conf下的nginx.conf文件）

upstream myproject{                    #server 183.232.41.1;                     server 42.156.140.7;                     server 61.129.48.158;           }   server {     listen       80;     server_name  nginx-01.itcast.cn;    #nginx所在服务器的主机名 #反向代理的配置 location / {             #拦截所有请求     root html;         proxy_pass http://192.168.0.21:8080;   #这里是代理走向的目标服务器：tomcat                  #proxy_pass http://myproject;     } }

2.启动tomcat-01上的tomcat

3.启动nginx-01上的nginx
./nginx

重启:
kill -HUP `cat /usr/local/nginx/logs/nginx.pid `
或者
/usr/local/nginx/sbin/nginx -s reload;


3.2. 动静分离#动态资源 index.jsp

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

#静态资源

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

3.3. 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 {     是在http里面的, 已有http, 不是在server里,在server外面     upstream tomcats {         server shizhan02:8080 weight=1;#weight表示多少个         server shizhan03:8080 weight=1;         server shizhan04:8080 weight=1; } #卸载server里 location ~ .*\.(jsp|do|action) {     proxy_pass http://tomcats;        #tomcats是后面的tomcat服务器组的逻辑组号 } }

4. 利用keepalived实现高可靠（HA）4.1. 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。

4.2. 高可靠软件keepalivedkeepalive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。
4.3. 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-1.2.19.tar.gz -C /usr/local/src

进入到/usr/local/src/keepalived-1.2.19目录
cd /usr/local/src/keepalived-1.2.19

开始configure
./configure --prefix=/usr/local/keepalived

#编译并安装
make && make install

4.4. 将keepalived添加到系统服务中拷贝执行文件

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

将init.d文件拷贝到etc下,加入开机启动项

cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived

将keepalived文件拷贝到etc下

cp /usr/local/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/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf

添加可执行权限

chmod +x /etc/init.d/keepalived

##以上所有命令一次性执行：

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/ cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ mkdir -p /etc/keepalived cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf chmod +x /etc/init.d/keepalived chkconfig --add keepalived chkconfig keepalived on

添加keepalived到开机启动
chkconfig --add keepalived
chkconfig keepalived on




4.5. 配置keepalived虚拟IP修改配置文件： /etc/keepalived/keepalived.conf
#MASTER节点

global_defs { } vrrp_instance VI_1 {     state MASTER   #指定A节点为主节点 备用节点上设置为BACKUP即可     interface eth0    #绑定虚拟IP的网络接口     virtual_router_id 51   #VRRP组名，两个节点的设置必须一样，以指明各个节点属于同一VRRP组     priority 100   #主节点的优先级（1-254之间），备用节点必须比主节点优先级低     advert_int 1  #组播信息发送间隔，两个节点设置必须一样     authentication {    #设置验证信息，两个节点必须一致         auth_type PASS         auth_pass 1111     }     virtual_ipaddress {    #指定虚拟IP, 两个节点设置必须一样         192.168.33.60/24    #如果两个nginx的ip分别是192.168.33.61,,...62，则此处的虚拟ip跟它俩同一个网段即可     } }

#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 {         192.168.33.60/24     } }

#分别启动两台机器上的keepalived
service keepalived start
测试：
杀掉master上的keepalived进程，你会发现，在slave机器上的eth0网卡多了一个ip地址
查看ip地址的命令：  ip addr

4.6. 配置keepalived心跳检查原理：
Keepalived并不跟nginx耦合，它俩完全不是一家人
但是keepalived提供一个机制：让用户自定义一个shell脚本去检测用户自己的程序，返回状态给keepalived就可以了


#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    #每隔1秒执行上述的脚本，去检查用户的程序ngnix     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