linux运维、架构之路-LVS负载均衡

一、LVS介绍

1、介绍   

       LVS是Linux Virtual Server的简写，是linux虚拟的服务器集群系统，可以在unix/linux平台下实现负载均衡集群功能，由章文嵩博士组织成立，是国内出现最早的自由软件之一。

LVS项目介绍
http://www.linuxvirtualserver.org/zh/lvs1.html
LVS集群的体系结构
http://www.linuxvirtualserver.org/zh/lvs2.html
LVS集群中的IP负载均衡技术
http://www.linuxvirtualserver.org/zh/lvs3.html
LVS集群的负载调度
http://www.linuxvirtualserver.org/zh/lvs4.html　　

2、LVS特性

①真正实现负载调度的工具是IPVS，工作在linux内核层面。
②LVS自带的IPVS管理工具是ipvsadm。
③keepalived实现管理IPVS及对负载均衡器的高可用。

3、LVS——DR模式工作原理

4、LVS集群其它模式

①DR直接路由模式(重点掌握)

②NAT

③TUN隧道模式

④FULLNAT

5、LVS应用场景

      日PV1000-2000W或者并发请求1W以下的都可以使用Nginx，超过的话使用LVS，大型门户网站，电商网站需要用到

二、手工配置LVS

1、环境

[root@lb01 ~]# cat /etc/redhat-release
CentOS Linux release 7.2. (Core)
[root@lb01 ~]# uname -r
3.10.-.el7.x86_64
[root@lb01 ~]# getenforce
Disabled
[root@lb01 ~]# systemctl status firewalld.service
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
   Active: inactive (dead)
[root@lb01 ~]# hostname -I
10.0.0.5 172.16.1.5

2、安装ipvsadm管理工具

①检测是否安装

[root@lb01 ~]# lsmod |grep ip_vs

②安装ipvsadm

yum -y install ipvsadm

③检查并激活lvs

[root@lb01 ~]# ipvsadm
IP Virtual Server version 1.2. (size=)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
[root@lb01 ~]# lsmod |grep ip_vs
ip_vs
nf_conntrack             ip_vs
libcrc32c                 xfs,ip_vs

3、配置LVS负载均衡(lb01操作)

ip addr add 10.0.0.3/24 dev eth0 #在eth0网卡绑定VIP地址
ipvsadm -C   #清除当前所有LVS规则
ipvsadm --set 30 5 60      #设置tcp、tcpfin、udp链接超时时间
ipvsadm -A -t 10.0.0.3:80 -s wrr -p 20   #添加虚拟服务（-A）
ipvsadm -a -t 10.0.0.3:80 -r 10.0.0.7:80 -g -w 1 #将虚拟服务关联到真实服务上（-a）
ipvsadm -a -t 10.0.0.3:80 -r 10.0.0.8:80 -g -w 1 #将虚拟服务关联到真实服务上（-a）
ipvsadm -ln #查看配置结果

-C 清空整个表
-A 添加一个虚拟服务
-t 指定一个地址，一定是ip+端口
-s 调度算法
-a 添加一个real server
-m NAT模式
-g DR模式，默认
-d 删除一个real server
-p 会话保持功能
-w 权重
-i tunnel模式

4、web服务器操作(web01、web02)

①在lo网卡绑定VIP地址

ip addr add 10.0.0.3/ dev lo

②修改内核参数抑制ARP响应

cat >>/etc/sysctl.conf<<EOF
net.ipv4.conf.all.arp_ignore =
net.ipv4.conf.all.arp_announce =
net.ipv4.conf.lo.arp_ignore =
net.ipv4.conf.lo.arp_announce =
EOF
sysctl -p

5、在lb02上面测试

[root@lb02 ~]# curl 10.0.0.3
web02
[root@lb02 ~]# curl 10.0.0.3
web02
[root@lb02 ~]# curl 10.0.0.3
web02
[root@lb02 ~]# curl 10.0.0.3
web02
[root@lb02 ~]# curl 10.0.0.3
web02
[root@lb02 ~]# curl 10.0.0.3
web01
[root@lb02 ~]# curl 10.0.0.3
web01

三、Keepalived配合LVS实现高可用负载均衡

1、安装Keepalived

yum -y install keepalived

2、配置keepalived管理LVS

global_defs { router_id LVS_01 } vrrp_instance VI_1 { state MASTER interface eth0 virtual_router_id 51 priority 150 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 10.0.0.3/24 } } virtual_server 10.0.0.3 80 { delay_loop 6 lb_algo wrr lb_kind DR nat_mask 255.255.255.0 persistence_timeout 50 protocol TCP real_server 10.0.0.7 80 { weight 1 TCP_CHECK { connect_timeout 8 nb_get_retry 3 delay_before_retry 3 connect_port 80 } } real_server 10.0.0.8 80 { weight 1 TCP_CHECK { connect_timeout 8 nb_get_retry 3 delay_before_retry 3 connect_port 80 } } }

global_defs { router_id LVS_02 } vrrp_instance VI_1 { state BACKUP interface eth0 virtual_router_id 51 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 10.0.0.3/24 } } virtual_server 10.0.0.3 80 { delay_loop 6 lb_algo wrr lb_kind DR nat_mask 255.255.255.0 persistence_timeout 50 protocol TCP real_server 10.0.0.7 80 { weight 1 TCP_CHECK { connect_timeout 8 nb_get_retry 3 delay_before_retry 3 connect_port 80 } } real_server 10.0.0.8 80 { weight 1 TCP_CHECK { connect_timeout 8 nb_get_retry 3 delay_before_retry 3 connect_port 80 } } }

 3、测试keepalived高可用，故障转移

①停掉lb01的keepalvied

[root@lb01 ~]# systemctl stop keepalived.service
[root@lb01 ~]# curl 10.0.0.3
web01

②停掉lb02的keepalvied

[root@lb02 ~]# systemctl stop keepalived.service
[root@lb02 ~]# curl 10.0.0.3
web01

4、测试Keepalived对后端节点的健康检查功能

①web后端正常时状态

[root@lb01 ~]# ipvsadm -ln
IP Virtual Server version 1.2. (size=)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  10.0.0.3: wrr persistent
  -> 10.0.0.7:                  Route
  -> 10.0.0.8:                  Route                    

②web后端节点宕机或者服务关闭时(此处关闭了web01)

[root@lb01 ~]# ipvsadm -ln
IP Virtual Server version 1.2. (size=)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  10.0.0.3: wrr persistent
  -> 10.0.0.7:                  Route                    

5、Keepalived+LVS多实例配置

①lb01

global_defs {
   router_id LVS_01
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id
    priority
    advert_int
    authentication {
        auth_type PASS
        auth_pass
    }
    virtual_ipaddress {
     10.0.0.3/
    }
}

vrrp_instance VI_2 {
    state BACKUP
    interface eth0
    virtual_router_id
    priority
    advert_int
    authentication {
        auth_type PASS
        auth_pass
    }
    virtual_ipaddress {
     10.0.0.4/
    }
}

virtual_server 10.0.0.3  {
    delay_loop
    lb_algo wrr
    lb_kind DR
    nat_mask 255.255.255.0
    persistence_timeout
    protocol TCP                

    real_server 10.0.0.7  {
        weight
        TCP_CHECK {
        connect_timeout
        nb_get_retry
        delay_before_retry
        connect_port
        }
    }

    real_server 10.0.0.8  {
        weight
        TCP_CHECK {
        connect_timeout
        nb_get_retry
        delay_before_retry
        connect_port
        }
    }
}

virtual_server 10.0.0.4  {
    delay_loop
    lb_algo wrr
    lb_kind DR
    nat_mask 255.255.255.0
    persistence_timeout
    protocol TCP                

    real_server 10.0.0.7  {
        weight
        TCP_CHECK {
        connect_timeout
        nb_get_retry
        delay_before_retry
        connect_port
        }
    }

    real_server 10.0.0.8  {
        weight
        TCP_CHECK {
        connect_timeout
        nb_get_retry
        delay_before_retry
        connect_port
        }
    }
}

②lb02

global_defs {
   router_id LVS_02
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id
    priority
    advert_int
    authentication {
        auth_type PASS
        auth_pass
    }
    virtual_ipaddress {
     10.0.0.3/
    }
}

vrrp_instance VI_2 {
    state MASTER
    interface eth0
    virtual_router_id
    priority
    advert_int
    authentication {
        auth_type PASS
        auth_pass
    }
    virtual_ipaddress {
     10.0.0.4/
    }
}

virtual_server 10.0.0.3  {
    delay_loop
    lb_algo wrr
    lb_kind DR
    nat_mask 255.255.255.0
    persistence_timeout
    protocol TCP                

    real_server 10.0.0.7  {
        weight
        TCP_CHECK {
        connect_timeout
        nb_get_retry
        delay_before_retry
        connect_port
        }
    }

    real_server 10.0.0.8  {
        weight
        TCP_CHECK {
        connect_timeout
        nb_get_retry
        delay_before_retry
        connect_port
        }
    }
}

virtual_server 10.0.0.4  {
    delay_loop
    lb_algo wrr
    lb_kind DR
    nat_mask 255.255.255.0
    persistence_timeout
    protocol TCP                

    real_server 10.0.0.7  {
        weight
        TCP_CHECK {
        connect_timeout
        nb_get_retry
        delay_before_retry
        connect_port
        }
    }

    real_server 10.0.0.8  {
        weight
        TCP_CHECK {
        connect_timeout
        nb_get_retry
        delay_before_retry
        connect_port
        }
    }
}