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    nginx的高可用，广为流传的便是keepalived+nginx了，下面就详细介绍下这个方案的搭建

环境准备

1

192.168.30.135【主】

192.168.30.128【备】

    主备都安装nginx，并且将index页面加入IP信息（方便后续观察VIP飘逸，主备切换）

keepalived安装

2

【1】下载安装包：

wget http://www.keepalived.org/software/keepalived-1.3.5.tar.gz

【2】解压安装包：[root@bogon src]# tar xvf keepalived-1.3.5.tar.gz

【3】编译安装

[root@bogon src]# cd keepalived-1.3.5

[root@bogon keepalived-1.3.5]# ./configure --prefix=/usr/local/keepalived

[root@bogon keepalived-1.3.5]# make

[root@bogon keepalived-1.3.5]# make install

 

需要安装openssl  不然会报错

yum -y install openssl-devel

注册为系统服务

3

【1】将解压之后的安装包中的keepalived文件复制到/etc/init.d/目录下

[root@bogon keepalived-1.3.5]# cp /root/keepalived/keepalived-1.3.5/keepalived/etc/init.d/keepalived /etc/init.d/keepalived

[root@bogon keepalived-1.3.5]# ll /etc/init.d/ | grep keepalived

-rwxr-xr-x  1 root root  1308 8月   2 14:15 keepalived

【2】修改/etc/init.d/keepalived启动脚本

需要修改的数据有以下几项：

# config: /etc/keepalived/keepalived.conf 文件的位置；

# Source configuration file (we set KEEPALIVED_OPTIONS there) 文件的位置。. /etc/sysconfig/keepalived

修改为实际安装的文件路径，我的安装路径如下：

# config: /usr/local/keepalived/etc/keepalived/keepalived.conf

. /usr/local/keepalived/etc/sysconfig/keepalived

另外添加如下变量，并修改文件中相应的部分：

keepalived=/usr/local/keepalived/sbin/keepalived

keepalived_config=/usr/local/keepalived/etc/keepalived/keepalived.conf

keepalived_pid=/var/run/keepalived.pid

【3】systemctl命令管理keepalived

systemctl start keepalived.service

systemctl stop keepalived.service

systemctl restart keepalived.service

systemctl status keepalived.service

如果报错，可以journalctl -xe查看具体失败信息

 

keepalived配置

4

配置文件：/usr/local/keepalived/etc/keepalived/keepalived.conf

下面提供最简单的配置，更多的可以自行查询

4.1·主节点配置

global_defs {

   router_id LVS_DEVEL

}

vrrp_instance VI_1 {

    state MASTER

    interface ens33

    virtual_router_id 51

    priority 100

    mcast_src_ip 192.168.30.135

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.30.140

    }

}

4.2·备节点配置

global_defs {

   router_id LVS_DEVEL

}

vrrp_instance VI_1 {

    state BACKUP

    interface ens33

    virtual_router_id 51

    priority 95

    mcast_src_ip 192.168.30.128

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.30.140

    }

}

 

使用验证

5

    按照上面的配置并启动之后，在主节点192.168.30.135上ip addr就可以看到配置文件中配置的VIP 192.168.30.140 了（备节点看不到这个vip）

    访问VIP 192.168.30.140   也可以看到访问到了主节点的nginx上

 

    将主节点的keepalive停掉之后，主节点ip addr上就卡不到该VIP了，在备节点可以看到，并且浏览器访问VIP会访问到备节点的nginx上

    但是如果主机点恢复了，那么VIP又会自动漂移会主节点

    一般keepalived的使用都会匹配值健康检测脚本，如果检测到对应的实例不可用，则干掉本机的keepalived，将VIP切换到备节点

 

问题记录

6

【1】Unable to find configuration fille

    这里是因为默认的配置文件路径还有没有修改的地方，需要修改如下文件的相应内容

    vi /usr/local/keepalived/etc/sysconfig/keepalived

【2】PID file /usr/local/keepalived/var/run/keepalived.pid not readable (yet?) after start

    查看下面文件中pid文件的路径配置，建议配置成  /var/run/keepalived.pid

vi /usr/lib/systemd/system/keepalived.service

vi  /etc/init.d/keepalived

 

【3】keepalive启动ok，但是vip无法访问（无法ping通）

将keepalived.conf中的vrrp_strict删除或者注释掉

完