LVS专题: LVS+Keepalived并使用DNS轮询实现Director的高可用和负载均衡
LVS专题: LVS+Keepalived并使用DNS轮询实现Director的高可用和负载均衡[*]
前言
LVS专题写到第三篇了, 前两篇我们对LVS的基础使用也有了一些了解, 这篇我们将做一个比较复杂的实验, 话不多说, 开始吧！
什么是KeepAlived
What is Keepalived ?
Keepalived is a routing software written in C. The main goal of this project is to provide simple and robust facilities for loadbalancing and high-availability to Linux system and Linux based infrastructures. Loadbalancing framework relies on well-known and widely used Linux Virtual Server (IPVS) kernel module providing Layer4 loadbalancing. Keepalived implements a set of checkers to dynamically and adaptively maintain and manage loadbalanced server pool according their health. On the other hand high-availability is achieved by VRRP protocol. VRRP is a fundamental brick for router failover. In addition, Keepalived implements a set of hooks to the VRRP finite state machine providing low-level and high-speed protocol interactions. Keepalived frameworks can be used independently or all together to provide resilient infrastructures. ##转自官方文档
大体的意思就是keepalived是一个由C语言编写的项目, 主要目标是提供负载均衡和高可用的Linux服务. keepalived依赖于Linux Virtual Server(IPVS)内核提供的四层负载均衡， keepalived实现了动态自适应和维护, 能够检测负载均衡池中的主机的健康状态, 而keepalived的高可用是通过VRRP(virtual route redundancy protocol)实现的.
关于VRRP协议参考文档H3C技术白皮书: VRRP、RFC 3768：Virtual Router Redundancy Protocol (VRRP)
实验介绍
大家都知道LVS虽然性能很强劲但是功能上有很多不足, 例如: 不能提供后端健康状态检查功能, director容易成为单点故障…, 而这些功能我们都可以通过第三方软件keepalived来提供, 而本次实验我们就要使用keepalived提供lvs-director的高可用, 并让两台director分别互为主从都能接受客户端通过dns对A记录的轮询请求从而转发至后端主机. 实现Director的高可用和负载均衡
实验拓扑
图画的不够形象, 实验中我们使用DR模型来进行实验
实验环境
VIP1为172.16.1.8、VIP2为172.16.1.9
主机IP地址功用director1.anyisalin.comVIP1,VIP2, DIP: 172.16.1.2Director1director2.anyisalin.comVIP1,VIP2, DIP: 172.16.1.3Director2rs1.anyisalin.comVIP, RIP: 172.16.1.4RealServer 1rs2.anyisalin.comVIP, RIP: 172.16.1.5RealServer 2ns.anyisalin.comIP: 172.16.1.10DNS
注意: 本文实验中所有主机SElinux和iptables都是关闭的
实验步骤
配置KeepAlived(1)
实现Director 的VIP互为主从
下面的操作都在director1上执行
# ntpdate 0.centos.pool.ntp.org#同步时间
# yum install keepalived &> /dev/null && echo success #安装keepalived
success
# vim /etc/keepalived/keepalived.conf #修改配置文件的部分配置如下
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
172.16.1.8 dev eth0 label eth0:0
}
}
vrrp_instance VI_2 {
state BACKUP
interface eth0
virtual_router_id 52
priority99
advert_int 1
authentication {
auth_type PASS
auth_pass 2222
}
virtual_ipaddress {
172.16.1.9 dev eth0 label eth0:1
}
}下面的操作都在director1上执行
# ntpdate 0.centos.pool.ntp.org#同步时间
# yum install keepalived &> /dev/null && echo success #安装keepalived
success
# vim /etc/keepalived/keepalived.conf #修改配置文件的部分配置如下
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 {
172.16.1.8 dev eth0 label eth0:0
}
}
vrrp_instance VI_2 {
state MASTER
interface eth0
virtual_router_id 52
priority100
advert_int 1
authentication {
auth_type PASS
auth_pass 2222
}
virtual_ipaddress {
172.16.1.9 dev eth0 label eth0:1
}
}同时在director1和director2上启动keepalived
# service keepalived start
# service keepalived start测试
默认情况director1和director2的ip如下
我们将director1的keepalived服务停止, 效果如下, IP自动转移到director2
我们将director1的keepalived服务再次启动, 效果如下， IP地址转回director1
配置LVS
配置KeepAlived(2)
这里我们使用DR模型进行实验, 因为keepalived可以通过调用ipvs的接口来自动生成规则, 所以我们这里无需ipvsadm, 但是我们要通过ipvsadm命令来查看一下ipvs规则
下面的操作在director1和director2都要执行, 由于篇幅过长, 遂不演示director2的操作
# yum install ipvsadm httpd &> /dev/null && echo success
success
# echo "Sorry, Service is Unavailable " > /var/www/html/index.html #配置sorry页面
# vim /etc/keepalived/keepalived.conf #修改keepalived配置文件, 添加以下段落
virtual_server 172.16.1.8 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
# persistence_timeout 50
protocol TCP
sorry_server 127.0.0.1 80
real_server 172.16.1.4 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
real_server 172.16.1.5 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}
virtual_server 172.16.1.9 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
# persistence_timeout 50
protocol TCP
sorry_server 127.0.0.1 80
real_server 172.16.1.4 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
real_server 172.16.1.5 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
}同时在director1和director2上重启keepalived
# service keepalived restart# service keepalived restart查看ipvs规则
# ipvsadm -L -n#正常IP Virtual Server version 1.2.1 (size=4096)Prot LocalAddress:Port Scheduler Flags-> RemoteAddress:Port Forward Weight ActiveConn InActConnTCP172.16.1.8:80 rr-> 172.16.1.4:80 Route 1 0 0 -> 172.16.1.5:80 Route 1 0 0 TCP172.16.1.9:80 rr-> 172.16.1.4:80 Route 1 0 0 -> 172.16.1.5:80 Route 1 0 0配置RS的IP和web服务
下面的操作都在rs1上执行
# yum install httpd -y &> /dev/null && echo success #安装httpd
success
# echo "This is 172.16.1.4" > /var/www/html/index.html #创建网页文件
# service httpd start #启动httpd服务
Starting httpd: httpd: apr_sockaddr_info_get() failed for director1.anyisalin.com
httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
# vim setup.sh #编写脚本配置相关内核参数和IP, 对这里不了解的看我上篇文章
#!/bin/bash
case $1 in
start)
echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
ifconfig lo:0 172.16.1.8/32 broadcast 172.16.1.8 up
ifconfig lo:1 172.16.1.9/32 broadcast 172.16.1.9 up
;;
stop)
echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
ifconfig lo:0 down
ifconfig lo:1 down
esac
# bash setup.sh start#运行脚本
# scp setup.sh 172.16.1.5:/root #将脚本传给rs2下面的操作都在rs1上执行
# yum install httpd -y &> /dev/null && echo success #安httpd
success
# echo "This is 172.16.1.4" > /var/www/html/index.html #创建网页文件# bash setup.sh start#运行脚本测试LVS
测试director1和director2
当我们关闭rs1的web服务, 会自动检查健康状态并删除
当我们同时关闭rs1和rs2的web服务, 会自动启用sorry server
配置DNS
配置dns的过程没什么好说的, 有兴趣可以看我的博客DNS and BIND 配置指南
下面的操作都在ns上执行
# yum install bind bind-utils -y --nogpgcheck &> /dev/null && echo success #安装bind
success
# vim /etc/named.conf #修改主配置文件如下
options {
directory "/var/named";
};
zone "." IN {
type hint;
file "named.ca";
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";
# vim /etc/named.rfc1912.zones #在文件尾部加上下列字段
zone "anyisalin.com" IN {
type master;
file "anyisalin.com.zone";
};
# vim /var/named/anyisalin.com.zone#创建区域配置文件
$TTL 600
$ORIGIN anyisalin.com.
@IN SOAns.anyisalin.com.admin.anyisalin.com. (
20160409
1D
5M
1W
1D
)
IN NSns
ns IN A 172.16.1.10
www IN A 172.16.1.8
www IN A 172.16.1.9
# service named start #启动named
Generating /etc/rndc.key:
Starting named: 测试DNS轮询效果
已经实现DNS轮询效果
最终测试
做了那么实验, 结合前面实验的效果, 来一次最终测试, 我将本机的DNS server指向了172.16.1.10以便测试
默认情况如下
我们将director2的keepalived强制关闭，依然不会影响访问
此时我们的director1的IP地址如下, 接管了director2的IP
总结
我们通过DNS轮询实现LVS-Director的负载均衡, KeepAlived实现Director的高可用, 而Director本身就可以为后端的RS进行负载均衡, 这一套架构还是很完整的. 其实本文还有很多不完善的地方, 但是由于我时间较紧, 遂不对其进行叙述, 希望大家多多谅解, LVS专题到这里可能结束了, 也可能会不定期的更新, 希望大家多多关注我的博客！
作者： AnyISalIn QQ：1449472454
感谢：MageEdu
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