keepalived+nginx高可用实现

1.keepalived介绍

　　keepalived最初是专为LVS负载均衡软件设计的，用来管理并监控LVS集群系统中各个服务节点的状态，后来又加入了实现高可用的VRRP功能。keepalived除了能够管理LVS软件外，还能支持其他服务的高可用解决方案。

　　keepalived通过VRRP协议实现高可用功能的。VRRP（Virtual Router Redundancy Protocol）虚拟路由冗余协议。VRRP出现的目的就是为了解决静态路由单点故障问题，它能保证当个别节点宕机时，整个网络可以不间断地运行。

2.keepalived高可用故障转移原理

　　keepalived高可用服务之间的故障转移，是通过VRRP来实现的。在keepalived服务工作时，主Master节点会不断地向备节点发送（多播的方式）心跳消息，用来告诉备Backup节点自己还活着。

　　当主节点发生故障时，无法给备节点发送心跳消息，如果备节点无法继续检测到来自主节点的心跳。就会调用自身的接管程序，接管主节点的IP资源和服务。当主节点恢复时，备节点又会释放主节点故障时自身接管的IP资源和服务，恢复到原来的备用角色

3.安装nginx

3.1.主节点（192.168.80.22）

3.1.1.安装编译工具和库文件

yum -y install make zlib zlib-devel gcc-c++ libtool  openssl openssl-devel

3.1.2.安装pcre

#进入目录
cd /usr/local/develop/anginx

#上传安装文件并解压
tar -zxvf pcre-8.38.tar.gz

#进入安装目录
cd pcre-8.38

#检查配置
./configure

#编译、安装
make && make install

#查看pcre版本
pcre-config --version

3.1.3.安装nginx

#进入目录
cd /usr/local/develop/anginx

#上传安装文件，并解压
tar -zxvf nginx-1.8.1.tar.gz

#进入安装目录
cd nginx-1.8.1

#检查配置
./configure --prefix=/usr/local/develop/anginx/webserver/nginx --with-http_stub_status_module --with-http_ssl_module --with-pcre=/usr/local/develop/anginx/pcre-8.38

#编译安装
make && make install

#查看nginx版本
 /usr/local/develop/anginx/webserver/nginx/sbin/nginx -v
--------------------------------------------------------
[root@hadoop02 webserver]# /usr/local/develop/anginx/webserver/nginx/sbin/nginx -v
nginx version: nginx/1.8.1

#配置nginx（检查）
/usr/local/develop/anginx/webserver/nginx/sbin/nginx -t

#nginx管理命令
/usr/local/develop/anginx/webserver/nginx/sbin/nginx              # 启动 Nginx
/usr/local/develop/anginx/webserver/nginx/sbin/nginx -s stop              # 停止 Nginx
/usr/local/develop/anginx/webserver/nginx/sbin/nginx -s reload            # 重新载入配置文件
/usr/local/develop/anginx/webserver/nginx/sbin/nginx -s reopen            # 重启 Nginx

3.1.4.nginx基础配置

vi nginx.conf

#user  nobody;
worker_processes  1;

#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  logs/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;
    
    #添加tomcat列表，真实应用服务器都放在这
    upstream tomcat_pool{
        #server tomcat地址:端口号 weight表示权值，权值越大，被分配的几率越大;
        server 192.168.80.22:8080 weight=4 max_fails=2 fail_timeout=30s;
        server 192.168.80.22:8081 weight=4 max_fails=2 fail_timeout=30s;
        
    }

    server {
        listen       80;
        server_name  tomcat_pool;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            #root   html;
            #index  index.html index.htm;
            proxy_pass http://tomcat_pool;    #转向tomcat处理
            proxy_set_header   Host             $host;
            proxy_set_header   X-Real-IP        $remote_addr;
            proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
        }

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }


}

3.2.备节点（192.168.80.21）

说明：安装方式同nginx主节点。

4.安装keepalived

4.1.主节点（192.168.80.22）

#安装keepalived
yum install keepalived -y

#启动keepalived服务
/etc/init.d/keepalived start
-------------------------------------------
[root@hadoop02 anginx]# /etc/init.d/keepalived start
正在启动 keepalived：                                      [确定]
[root@hadoop02 anginx]# ps -ef |grep keepalived
root      15723      1  0 00:59 ?        00:00:00 /usr/sbin/keepalived -D
root      15724  15723  0 00:59 ?        00:00:00 /usr/sbin/keepalived -D
root      15725  15723  0 00:59 ?        00:00:00 /usr/sbin/keepalived -D
root      15731  15622  0 00:59 pts/1    00:00:00 grep keepalived
[root@hadoop02 anginx]#

#设置开机自启动
echo "/etc/init.d/keepalived start" >>/etc/rc.local

#关闭keepalived服务
/etc/init.d/keepalived stop

#编辑keepalived配置文件
vi /etc/keepalived/keepalived.conf

-----------------------------------------------------------
! Configuration File for keepalived

global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id lb01
}

vrrp_instance VI_1 {
    state MASTER
    interface eth1
    virtual_router_id 55
    priority 150
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass server123
    }
    virtual_ipaddress {
        192.168.80.100 dev eth1 label eth1:1
    }
}
...........................................................

关于配置说明：

 【router_id】 是路由标识，在一个局域网里面应该是唯一的
 
 【vrrp_instance VI_1】{...}这是一个VRRP实例，里面定义了keepalived的主备状态、接口、优先级、认证和IP信息
    【state】 定义了VRRP的角色
    【interface】定义使用的接口，这里我的服务器用的网卡都是eth1
    【virtual_router_id】是虚拟路由ID标识，一组的keepalived配置中主备都是设置一致
    【priority】是优先级，数字越大，优先级越大，
    【auth_type】是认证方式
    【auth_pass】是认证的密码
    
 【virtual_ipaddress】 ｛...｝定义虚拟IP地址，可以配置多个IP地址，这里我定义为192.168.80.100，绑定了eth1的网络接口，虚拟接口eth1:1

4.2.备节点（192.168.80.21）

#安装keepalived
yum install keepalived -y

#启动keepalived服务
/etc/init.d/keepalived start
-------------------------------------------
[root@hadoop02 anginx]# /etc/init.d/keepalived start
正在启动 keepalived：                                      [确定]
[root@hadoop02 anginx]# ps -ef |grep keepalived
root      15723      1  0 00:59 ?        00:00:00 /usr/sbin/keepalived -D
root      15724  15723  0 00:59 ?        00:00:00 /usr/sbin/keepalived -D
root      15725  15723  0 00:59 ?        00:00:00 /usr/sbin/keepalived -D
root      15731  15622  0 00:59 pts/1    00:00:00 grep keepalived
[root@hadoop02 anginx]#

#设置开机自启动
echo "/etc/init.d/keepalived start" >>/etc/rc.local

#关闭keepalived服务
/etc/init.d/keepalived stop

#编辑keepalived配置文件
vi /etc/keepalived/keepalived.conf

-----------------------------------------------------------------
! Configuration File for keepalived

global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id lb02
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth1
    virtual_router_id 55
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass server123
    }
    virtual_ipaddress {
        192.168.80.100 dev eth1 label eth1:1
    }
}
.............................................................

5.测试

5.1.启动主备节点的keepalived服务

#在节点一执行（192.168.80.22）
/etc/init.d/keepalived start
-------------------------------------
[root@hadoop02 anginx]# ps -ef |grep keepalived
root      15788      1  0 01:09 ?        00:00:00 /usr/sbin/keepalived -D
root      15790  15788  0 01:09 ?        00:00:00 /usr/sbin/keepalived -D
root      15791  15788  0 01:09 ?        00:00:00 /usr/sbin/keepalived -D
root      15807  15622  0 01:33 pts/1    00:00:00 grep keepalived
[root@hadoop02 anginx]#


#在节点二执行（192.168.80.21）
/etc/init.d/keepalived start
---------------------------------------
[root@hadoop01 ~]# ps -ef |grep keepalived
root      11542      1  0 01:30 ?        00:00:00 /usr/sbin/keepalived -D
root      11544  11542  0 01:30 ?        00:00:00 /usr/sbin/keepalived -D
root      11545  11542  0 01:30 ?        00:00:00 /usr/sbin/keepalived -D
root      11550  11512  0 01:33 pts/1    00:00:00 grep keepalived
[root@hadoop01 ~]#

5.2.通过虚ip访问服务

http://192.168.80.100/session-redis-demo/

5.3.停止主节点keepalived服务

#在节点一执行（192.168.80.22）
/etc/init.d/keepalived stop

#观察备节点变化
ip addr
-------------------------------------------
[root@hadoop01 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:50:56:38:e5:46 brd ff:ff:ff:ff:ff:ff
    inet 192.168.80.21/24 brd 192.168.80.255 scope global eth1
    inet 192.168.80.100/32 scope global eth1:1
    inet6 fe80::250:56ff:fe38:e546/64 scope link 
       valid_lft forever preferred_lft forever
[root@hadoop01 ~]#

5.4.继续通过虚ip访问服务