Nginx keepalived实现高可用负载均衡详细配置步骤

Keepalived是一个免费开源的，用C编写的类似于layer3, 4 & 7交换机制软件，具备我们平时说的第3层、第4层和第7层交换机的功能。主要提供loadbalancing（负载均衡）和high-availability（高可用）功能，负载均衡实现需要依赖Linux的虚拟服务内核模块（ipvs），而高可用是通过VRRP协议实现多台机器之间的故障转移服务。

主要讲述一下Keepalived编译和安装出现的问题以及解决方法，本人使用keepalived-1.3.5.tar.gz。

官网源码包下载地址（2017-07-31 Keepalived最新版keepalived-1.3.5.tar.gz）：http://www.keepalived.org/download.html

[root@iZ256w2hluuZ local]# tar -zxvf /tmp/keepalived-1.3.5.tar.gz 
[root@iZ256w2hluuZ local]# cd keepalived-1.3.5/
[root@iZ256w2hluuZ keepalived-1.3.5]# ./configure --prefix=/usr/local/keepalived

1. 系统出现警告信息“*** WARNING - this build will not support IPVS with IPv6. Please install libnl/libnl-3 dev libraries to support IPv6 with IPVS.”，具体日志如下：

Keepalived configuration
------------------------
Keepalived version       : 1.3.5
Compiler                 : gcc
Preprocessor flags       : 
Compiler flags           : -Wall -Wunused -Wstrict-prototypes -Wextra -g -O2
Linker flags             : 
Extra Lib                :  -lcrypto  -lssl 
Use IPVS Framework       : Yes
IPVS use libnl           : No
IPVS syncd attributes    : No
IPVS 64 bit stats        : No
fwmark socket support    : Yes
Use VRRP Framework       : Yes
Use VRRP VMAC            : Yes
Use VRRP authentication  : Yes
With ip rules/routes     : Yes
SNMP vrrp support        : No
SNMP checker support     : No
SNMP RFCv2 support       : No
SNMP RFCv3 support       : No
DBUS support             : No
SHA1 support             : No
Use Debug flags          : No
Stacktrace support       : No
Memory alloc check       : No
libnl version            : None
Use IPv4 devconf         : No
Use libiptc              : No
Use libipset             : No
init type                : upstart
Build genhash            : Yes
Build documentation      : No

*** WARNING - this build will not support IPVS with IPv6. Please install libnl/libnl-3 dev libraries to support IPv6 with IPVS.

解决方案一：（在线安装）

执行yum命令yum -y install libnl libnl-devel解决上述警告问题

[root@iZ256w2hluuZ keepalived-1.3.5]# yum -y install libnl libnl-devel

解决方案二：（离线安装）

离线安装libnl-devel包，从网上下载libnl-devel-1.1.4-2.el6.x86_64.rpm包，执行rpm -ivh libnl-devel-1.1.4-2.el6.x86_64.rpm命令。

[root@iZ256w2hluuZ other-packages]# wget http://mirror.centos.org/centos/6/os/x86_64/Packages/libnl-devel-1.1.4-2.el6.x86_64.rpm
####执行wget命令是从另外一台可以连接外网的服务器上下载libnl-devel-1.1.4-2.el6.x86_64.rpm包的命令，可以忽略，只是为大家提供个下载libnl-devel地址####

[root@iZ256w2hluuZ other-packages]# rpm -ivh libnl-devel-1.1.4-2.el6.x86_64.rpm 
Preparing...                ########################################### [100%]
        package libnl-devel-1.1.4-2.el6.x86_64 is already installed

安装完成以后，重新执行configure命令

[root@iZ256w2hluuZ keepalived-1.3.5]# ./configure --prefix=/usr/local/keepalived

2. 系统出现错误信息“configure: error: libnfnetlink headers missing”，具体日志如下：

checking for nl_socket_modify_cb in -lnl... yes
checking for linux/rtnetlink.h... yes
checking libnfnetlink/libnfnetlink.h usability... no
checking libnfnetlink/libnfnetlink.h presence... no
checking for libnfnetlink/libnfnetlink.h... no
configure: error: libnfnetlink headers missing

解决方案一：（在线安装）

执行yum命令yum install -y libnfnetlink-devel解决上述错误问题

[root@iZ256w2hluuZ keepalived-1.3.5]# yum install -y libnfnetlink-devel

解决方案二：（离线安装）

Linux执行wget下载rpm包（离线安装libnfnetlink包时所需rpm包，执行wget下载libnfnetlink rpm包命令，此步可以忽略，只是为大家提供个下载libnfnetlink地址），具体命令如下：

wget ftp://mirror.switch.ch/mirror/centos/6/os/x86_64/Packages/libnfnetlink-1.0.0-1.el6.x86_64.rpm
wget ftp://mirror.switch.ch/mirror/centos/6/os/x86_64/Packages/libnfnetlink-devel-1.0.0-1.el6.x86_64.rpm

执行rpm -ivh libnfnetlink-1.0.0-1.el6.x86_64.rpm命令安装libnfnetlink-1.0.0-1.el6.x86_64.rpm包，具体如下：

[root@iZ256w2hluuZ other-packages]# rpm -ivh libnfnetlink-1.0.0-1.el6.x86_64.rpm 
Preparing...                ########################################### [100%]
   1:libnfnetlink           ########################################### [100%]

执行rpm -ivh libnfnetlink-devel-1.0.0-1.el6.x86_64.rpm命令安装libnfnetlink-devel-1.0.0-1.el6.x86_64.rpm包，具体如下：

[root@iZ256w2hluuZ other-packages]# rpm -ivh libnfnetlink-devel-1.0.0-1.el6.x86_64.rpm
Preparing...                ########################################### [100%]
   1:libnfnetlink-devel     ########################################### [100%]

安装完成以后，重新执行configure命令

[root@iZ256w2hluuZ keepalived-1.3.5]# ./configure --prefix=/usr/local/keepalived

3. 编译keepalived不会出现上述警告和其他错误，执行make && make install命令进行安装：

[root@iZ256w2hluuZ keepalived-1.3.5]# make && make install

至此Keepalived编译并安装结束，在下一篇文章中会详解介绍Nginx搭配Keepalived的详细配置和使用方法，欢迎大家收藏本站素文宅博客。

使用命令 /usr/local/keepalived/sbin -h 参看各启动参数，启动命令：

[root@iZ256w2hluuZ keepalived-1.3.5]# ./sbin/keepalived -f /usr/local/keepalived/etc/keepalived.conf

制作快捷启动，在源文件的目录./keepalived-1.3.5/keepalived/etc/init.d下有两个个快捷启动文件和生成/usr/local/keepalived目录下一个配置文件需要复制，具体执行如下命令：

[root@iZ256w2hluuZ keepalived-1.3.5]#  cp ./keepalived-1.3.5/keepalived/etc/init.d/keepalived /etc/init.d/
[root@iZ256w2hluuZ keepalived-1.3.5]#  cp  /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
[root@iZ256w2hluuZ keepalived-1.3.5]#  cp ./keepalived-1.3.5/keepalived/etc/sysconfig/keepalived /etc/sysconfig/keepalived

这样就可以执行service keepalived [start | stop | reload | restart ]命令。

启动报“Starting keepalived: /bin/bash: keepalived: command not found”错误，具体日志如下：

[root@yoodb /]# service keepalived start
正在启动 keepalived：/bin/bash: keepalived: command not found
                                                           [失败]

解决方案：

[root@yoodb /]# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
[root@yoodb /]# service keepalived start
正在启动 keepalived：                                      [确定]
[root@yoodb /]# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

有上述日志信息，表示启动成功。

前面我们已经讲述了Keepalived-1.3.5编译安装和制作快捷启动方式，下面主要说一说如何在两台服务器分布部署Nginx，通过keepalived实现高可用。

准备工作：

Linux操作系统Centos6.5，两台接入服务器公用一个虚拟IP（VIP）123.57.47.154

配置Nginx

两台接入服务器Nginx配置完全相同，配置文件目录/usr/local/nginx/conf/nginx.conf，配置内容如下：

upstream blog.yoodb.com { 
      server  192.168.1.1; 
      server  192.168.1.2; 
} 
  
server{ 
    listen 80; 
    server_name blog.yoodb.com; 
    location / { 
        proxy_pass         http://127.0.0.1:8081; 
        proxy_set_header   Host             $host; 
        proxy_set_header   X-Real-IP        $remote_addr; 
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for; 
    } 
}

配置keepalived

keepalived的配置文件/etc/keepalived/keepalived.conf，注意主、从服务器的keepalived配置相关联有所不同，配置如下：

主Master：

! Configuration File for keepalived

global_defs {
notification_email {
        yoodb.com@gmail.com
   }

   notification_email_from yoodb.com@gmail.com
   smtp_server smtp.gmail.com
   smtp_connect_timeout 30
   router_id nginx_master

}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 101
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        123.57.47.154
    }
}

从Backup：

! Configuration File for keepalived

global_defs {
notification_email {
        yoodb.com@gmail.com
   }

   notification_email_from yoodb.com@gmail.com
   smtp_server smtp.gmail.com
   smtp_connect_timeout 30
   router_id nginx_backup

}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 99
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        123.57.47.154
    }
}

验证：

先后启动主、从服务器上keepalived，执行/etc/init.d/keepalived start命令

利用ip a命令查看主服务器虚拟IP是否绑定成功

停止主服务器上的keepalived，执行/etc/init.d/keepalived stop命令访问123.57.47.154是否依然能够访问web页面，再次利用ip a命令查看从服务器虚拟IP是否绑定成功。

启动主服务器上的keepalived，看看主服务器能否重新接管虚拟IP。