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

        }

    }

}

巴特西

linux运维、架构之路-LVS负载均衡

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