Keepalived + HAProxy 搭建【第二篇】Keepalived 的安装与配置

第一步：准备

1. 简介

　　本文搭建的是利用 Keepalived 实现 HAProxy 的热备方案，即两台主机上的 HAProxy 实例同时运行，其中全总较高的实例为 MASTER，MASTER出现异常时，另一台主机上的实例自动接管所有的流量。

　　在运行着 HAProxy 实例的两台主机上分别运行着 Keepalived 实例，这两个 Keepalived 争抢同一个虚 IP 地址，两个 HAProxy 也尝试着去绑定同一个虚 IP 地址上的端口。只能有一个 Keepalived 能抢到这个虚 IP，抢到这个虚 IP 的 Keepalived 的主机上的 HAProxy 即为当前的 MASTER。

　　Keepalived 内部维护一个权重值，权重值最高的 Keepalived 实例能够抢到虚 IP。Keepalived 会定期检查所在主机上的 HAProxy 的状态，状态健康时，则权重值增加。

2. 操作系统

CentOS-7-x86_64-Everything-1511

3. 安装包

keepalived-1.3.4.tar.gz

4. HAProxy 安装

参照 Keepalived + HAProxy 搭建【第一篇】HAProxy 的安装和配置在另一台主机（本文为192.168.6.129）上安装 HAProxy 实例。

5. 安装 psmisc

使用 killall -0 检查 HAProxy 服务是否存在。如果没有 killall 命令，则需要安装 psmisc 包。

# yum intall psmisc

6. 安装 openssl

# yum install openssl-devel

不安装 openssl，keepalived 编译的时候会报错：

7. 安装 libnl/libnl-3 库

# yum install libnl*

不安装 libnl/libnl-3，keepalived 编译的时候会报警告：

8. 安装

# yum install libnfnetlink-devel

不安装 libnfnetlink-devel，keepalived 编译的时候会报错：

第二步：安装与配置

1. 安装

# tar zxzf keepalived-1.3.4.tar.gz
# # cd keepalived-1.3.4
# ./configure --prefix=/usr/local/keepalived
# make
# make install

2. 配置

1）注册为系统服务

# cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
# touch /etc/init.d/keepalived
# chmod +x /etc/init.d/keepalived
# vi /etc/init.d/keepalived

/etc/init.d/keepalived 的文件内容：

#!/bin/sh
#
# Startup script for the Keepalived daemon
#
# processname: keepalived
# pidfile: /var/run/keepalived.pid
# config: /etc/keepalived/keepalived.conf
# chkconfig: - 21 79
# description: Start and stop Keepalived

# Source function library
. /etc/rc.d/init.d/functions

# Source configuration file (we set KEEPALIVED_OPTIONS there)
. /etc/sysconfig/keepalived

RETVAL=0

prog="keepalived"

start() {
    echo -n $"Starting $prog: "
    daemon keepalived ${KEEPALIVED_OPTIONS}
    RETVAL=$?
    echo
    [ $RETVAL -eq 0 ] && touch /var/lock/subsys/$prog
}

stop() {
    echo -n $"Stopping $prog: "
    killproc keepalived
    RETVAL=$?
    echo
    [ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/$prog
}

reload() {
    echo -n $"Reloading $prog: "
    killproc keepalived -1
    RETVAL=$?
    echo
}

# See how we were called.
case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    reload)
        reload
        ;;
    restart)
        stop
        start
        ;;
    condrestart)
        if [ -f /var/lock/subsys/$prog ]; then
            stop
            start
        fi
        ;;
    status)
        status keepalived
        RETVAL=$?
        ;;
    *)
        echo "Usage: $0 {start|stop|reload|restart|condrestart|status}"
        RETVAL=1
esac

exit $RETVAL

2）编辑配置文件

# mkdir /etc/keepalived/
# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
# vi /etc/keepalived/keepalived.conf

配置文件内容：

global_defs {
    router_id LVS_DEVEL  #虚拟路由名称
}

#HAProxy健康检查配置
vrrp_script chk_haproxy {
    script "killall -0 haproxy"  #使用killall -0检查haproxy实例是否存在，性能高于ps命令
    interval 2   #脚本运行周期
    weight 2   #每次检查的加权权重值
}

#虚拟路由配置
vrrp_instance VI_1 {
    state MASTER           #本机实例状态，MASTER/BACKUP，备机配置文件中请写BACKUP
    interface eno16777736      #本机网卡名称，使用ifconfig命令查看
    virtual_router_id 51   #虚拟路由编号，主备机保持一致
    priority 101           #本机初始权重，备机请填写小于主机的值（例如100）
    advert_int 1           #争抢虚地址的周期，秒
    virtual_ipaddress {
        192.168.6.131      #虚地址IP，主备机保持一致
    }
    track_script {
        chk_haproxy        #对应的健康检查配置
    }
}