本文详细介绍使用Keepalived和LVS实现高可用负载均衡的配置步骤，包括主备切换、健康检查及主主模式的实现，适用于大规模访问场景。
1.keepalived高可用lvs
简介:
用lvs做负载均衡，作为架构的最前端，随着日益增长的访问量，需要给负载均衡做高可用架构，利用keepalived解决单点风险，一旦主节点宕机能快速切换到备节点服务器
配置前提:
(1)各节点时间必须同步:(ntpdate,chronyd)
(2)确保iptables和selinux不会成为阻碍
(3)确保各节点的用于集群服务的主机接口支持multicast通信(多播)
拓扑图:
下载:yum -y install keepalived ipvsadm
keep1配置文件: /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost #故障发生时给谁发邮件通知
}
notification_email_from keepalived@localhost #邮件由那个用户发出
smtp_server 127.0.0.1 #邮箱地址
smtp_connect_timeout 30 #邮箱连接超时时长
router_id keep1 #路由主机名
vrrp_mcast_group4 224.1.11.111 #组播地址,地址范围224-239,与keep2保持一致
}
vrrp_instance VI_1 {
state MASTER #主keepalived
interface ens33 #网卡接口
virtual_router_id 111 #当前虚拟路由器的惟一标识，范围是0-255,与keep2保持一致
priority 100 #优先级,范围1-254,数字越大优先级越高,keep2必须小于keep1
advert_int 1 #vrrp通告的时间间隔
authentication {
auth_type PASS
auth_pass like5453 #随机数,与keep2保持一致
}
virtual_ipaddress {
10.117.20.99/24 dev ens33 label ens33:0 #vip地址
}
}
virtual_server 10.117.20.99 80 {
delay_loop 1 #隔一秒检测一次后端主机
lb_algo wrr #调度算法,wrr为加权轮询
lb_kind DR #lvs类型
protocol TCP #协议
sorry_server 127.0.0.1 80 #表示如果后端主机都掉线,转到本机的80端口服务
real_server 10.117.20.225 80 {
weigth 1 #权重
HTTP_GET { #健康检测方式
url { #指定对那个url发请求,url可以重复多次,默认对主页发送请求
path /index.html
status_code 200
}
nb_get_retry 3 #尝试几次来做检测
delay_before_retry 2 #延迟重试时长
connect_timeout 3 #连接超时时长,默认5秒
}
}
real_server 10.117.20.226 80 {
weigth 1
HTTP_GET {
url {
path /index.html
status_code 200
}
nb_get_retry 3
delay_before_retry 2
connect_timeout 3
}
}
}
keep2 配置文件: 需要修改的地方下面都已经指出来,其他参数保持不变
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id keep2 #此处需要修改
vrrp_mcast_group4 224.1.11.111
}
vrrp_instance VI_1 {
state BACKUP #此处需要修改
interface ens33
virtual_router_id 111
priority 90 #此处需要修改
advert_int 1
authentication {
auth_type PASS
auth_pass like5453
}
virtual_ipaddress {
10.117.20.99/24 dev ens33 label ens33:0
}
}
virtual_server 10.117.20.99 80 {
delay_loop 1
lb_algo wrr
lb_kind DR
protocol TCP
sorry_server 127.0.0.1 80
real_server 10.117.20.225 80 {
weigth 1
HTTP_GET {
url {
path /index.html
status_code 200
}
nb_get_retry 3
delay_before_retry 2
connect_timeout 3
}
}
real_server 10.117.20.226 80 {
weigth 1
HTTP_GET {
url {
path /index.html
status_code 200
}
nb_get_retry 3
delay_before_retry 2
connect_timeout 3
}
}
}
修改RS主机内核参数:
#!/bin/bash
#修改rs主机内核参数,以及添加vip地址和路由
vip='10.117.20.99'
mask='255.255.255.255'
iface='lo:0'
broad='10.117.20.99'
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 $iface $vip netmask $mask broadcast $broad up
route add -host $vip $iface
;;
stop)
ifconfig $iface down
echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore
echo 0 > /proc/sys/net/ipv4/conf/all/arp_announ ce
echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce
;;
*)
echo "usege start|stop"
exit 1
;;
esac
#分别在两台RS主机运行此脚本
启动服务:
[root@keep2 ~]#systemctl start keepalived #先启动keep2,等一下在启动keep1,可以看看主备切换的效果
[root@s1 ~]#systemctl start nginx
[root@s2 ~]#systemctl start nginx
keep2 检查vip地址:
检查lvs状态,成功检测到RS主机:
客户端访问测试:
把keep1启动起来:
vip地址自动切换到keep1
keep2 检查vip地址
keep1查看lvs状态,成功检测到RS主机:
测试把RS1主机关掉, 实现自动移除的功能:
客户端测试,现在只能请求到RS2主机 :
测试把两台RS主机都关掉,看能不能切换到keepalive本机的错误提示页:
客户端访问:
最后在把两台RS主机启动起来,都成功的被自动添加:
基于脚本的方法切换主备节点:
功用:不用把keepalived关闭,就能实现主备切换,降低主keep优先级的方式实现
1.编写脚本:
[root@keep1 ~]#vim /etc/keepalived/chk_down.sh
#!/bin/bash
[[-f /etc/keepalived/down ]] && exit 1 || exit 0
2.配置文件定义脚本参数:
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id keep1
vrrp_mcast_group4 224.1.11.111
}
#定义检查参数
vrrp_script chk_down {
script "/etc/keepalived/chk_down.sh" #指定脚本的绝对路径
weight -10 #降权10,降权以后必须小于备用节点.
interval 1 #一秒检查一次
fall 1 #检查几次
rise 1
}
vrrp_instance VI_1 {
state MASTER
interface ens33
virtual_router_id 111
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass like5453
}
virtual_ipaddress {
10.117.20.99/24 dev ens33 label ens33:0
}
#引用脚本
track_script {
chk_down
}
}
测试主备转换过程:
先把两台主机都启动起来,然后在keep1主机的/etc/keepalived/目录下创建一个down文件,这时脚本检测到down文件存在,然后keep1主机自动从100降权到90,变成备用节点,在keep2主机上抓包可以清楚看到地址的转换过程,
如果想把主节点切换回来只需要删除down文件:
====================================================================
2.nginx+keepalived实现高可用
提前准备:分别在两台主机上安装,nginx+keepalivd
1.keepalived配置文件: vim /etc/keepalived/keepalived.conf #两台主机除了主备参数需要修改以外,其他配置一样
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id keep1 #备服务器修改为 keep2
vrrp_mcast_group4 224.1.11.111
}
vrrp_instance VI_1 {
state MASTER #备服务器,修改为BACKUP
interface ens33
virtual_router_id 111
priority 100 #备服务器,优先级修改为90
advert_int 1
authentication {
auth_type PASS
auth_pass like5453
}
virtual_ipaddress {
10.117.20.99/24 dev ens33 label ens33:0
}
}
2.修改nginx配置文件:vim /etc/nginx/nginx.conf #两台nginx配置一样, 在http段中定义一个后端服务器组,然后在location中引用
3.测试:
4.把server1关掉,测试健康状态检查:
5.再次把server1启动:
=====================================================================
3.实现 keeplived主主模型
下面的配置文件中没有配置virtual_server,其配置方法和主备模式一样,这里主要看一下主主模式的效果
keep1 配置文件:
[root@keep1 /etc/keepalived]#cat keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id keep1
vrrp_mcast_group4 224.1.11.111
}
vrrp_instance VI_1 {
state MASTER
interface ens33
virtual_router_id 111
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass like5453
}
virtual_ipaddress {
10.117.20.99/24 dev ens33 label ens33:0
}
}
vrrp_instance VI_2 { #需要修改
state BACKUP #需要修改
interface ens33
virtual_router_id 110 #需要修改
priority 95 #需要修改
advert_int 1
authentication {
auth_type PASS
auth_pass like #需要修改
}
virtual_ipaddress {
10.117.20.98/24 dev ens33 label ens33:1 #需要修改
}
}
keep2配置文件:
[root@keep2 ~]#cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id keep2
vrrp_mcast_group4 224.1.11.111
}
vrrp_instance VI_1 {
state BACKUP
interface ens33
virtual_router_id 111
priority 95
advert_int 1
authentication {
auth_type PASS
auth_pass like5453
}
virtual_ipaddress {
10.117.20.99/24 dev ens33 label ens33:0
}
}
vrrp_instance VI_2 {
state MASTER
interface ens33
virtual_router_id 110
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass like
}
virtual_ipaddress {
10.117.20.98/24 dev ens33 label ens33:1
}
}
查看状态:双主模型已经成功
4.采用varnish为nginx实现缓存加速
准备工作:
1.一台varnish缓存服务器,一台nginx服务器
2.关闭防火墙和selinux
3.两台服务器同步时间:ntpdate ntp6.aliyun.com
注意:重启varnish缓存失效
安装varnish:
yum -y install varnish
修改配置文件: /etc/varnish/varnish.params
创建目录:mkdir -pv /data/varnish/cache
修改属主:chown varnish.varnish /data/varnish/cache
default.vcl配置文件:/etc/varnish/default.vcl
如果平时修改了default.vcl文件可以用varnish_reload_vcl命令重载
启动:systemctl start varnish
测试:
后台管理命令行: varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082
5.LNMP结合varnish实现动静分离
#new 4.0 format.
vcl 4.0;
backend server1 {
.host = "10.117.20.226";
.port = "80";
}
backend server2 {
.host = "10.117.20.225";
.port = "80";
}
sub vcl_recv {
if(req.url ~ "\.(html|jpeg|png)$"){
set req.backend_hint = server1;
}else{
if(req.url ~ "\.(php|js|perl)$"){
set req.backend_hint = server2;
}
}
}
测试:
附加内容:
-------------------------------------------------------------------------------
设置多个后端主机:
示例:
#new 4.0 format.
vcl 4.0;
import directors; #定义后端主机组,需要用到的模块
#Default backend definition. Set this to point to your content server.
backend server1{
.host = "192.168.1.111";
.port = "80";
}
backend server2{
.host = "192.168.1.112";
.port = "80";
}
sub vcl_init {
new webserver = directors.round_robin(); #声明一个组为webserver,里面填定义好的后端主机.
webserver.add_backend(server1);
webserver.add_backend(server2);
}
sub vcl_recv {
set req.backend_hint = webserver.backend(); #调用webserver组
}
--------------------------------------------------------------------
后端主机健康状态检测:
示例:
#new 4.0 format.
vcl 4.0;
#Default backend definition. Set this to point to your content server.
probe web_probe {
.url = "/index.html" ; #检测请求的文件内容
.interval = 1s; #1秒发一次请求
.timeout = 1s; #超时时间
.window = 5; #一共检测5次
.threshold = 3; #必须成功三次,才认为是健康的
}
backend server1{
.host = "192.168.1.111";
.port = "80";
.probe = web_probe; #调用上面定义probe
}
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