LVS(Linux Virtual Server)

LVS 是一个虚拟服务器集群系统,通过负载均衡技术将请求分发到多个后端服务器上,实现高可用性和高扩展性。LVS 本身并不处理应用层的数据,而是工作在网络层,处理 IP 数据包。

LVS 的主要组件

  1. ipvsadm:LVS 的管理工具,用于配置和管理 LVS。
  2. Virtual Server:虚拟服务器,通过一个 IP 地址(VIP)对外提供服务。
  3. Real Server:真实服务器,真正处理请求的服务器。

LVS 工作模式

  1. NAT 模式(Network Address Translation):在这种模式下,LVS 会修改请求数据包的目标 IP 地址,然后将数据包发送到真实服务器,并将响应数据包修改为源 IP 地址,再返回给客户端。
  2. DR 模式(Direct Routing):LVS 仅修改数据包的 MAC 地址,然后直接将数据包发送到真实服务器。真实服务器直接响应客户端。
  3. TUN 模式(IP Tunneling):LVS 通过 IP 隧道将数据包发送到真实服务器。真实服务器通过隧道返回响应数据包。

Keepalived

Keepalived 是一个用于实现高可用性(HA)的软件,通常与 LVS 配合使用。它通过 VRRP(Virtual Router Redundancy Protocol)来实现主备切换,从而保证服务的高可用性。

Keepalived 的主要功能

  1. 健康检查:通过配置健康检查脚本,Keepalived 可以监控 LVS 的状态和后端真实服务器的状态。
  2. 故障转移:当检测到 LVS 或真实服务器故障时,Keepalived 会自动进行故障转移。
  3. VRRP 实现 VIP 漂移:通过 VRRP 实现 VIP 漂移,在主服务器故障时,将 VIP 转移到备服务器。

构建 LVS+Keepalived 高可用集群

keepalived的安装与服务控制

[root@localhost ~]# systemctl stop NetworkManager

[root@localhost ~]# setenforce 0

[root@localhost ~]# systemctl stop firewalld

[root@localhost ~]# yum -y install keepalived ipvsadm

[root@localhost ~]# systemctl enable keepalived

使用keepalived实现双机热备

主服务器的配置

[root@localhost ~]# cd /etc/keepalived/

[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bak

[root@localhost keepalived]# vi keepalived.conf

global_defs {

   notification_email {

     acassen@firewall.loc

     failover@firewall.loc

     sysadmin@firewall.loc

   }

   notification_email_from Alexandre.Cassen@firewall.loc

   smtp_server 192.168.200.1

   smtp_connect_timeout 30

   router_id LVS_01

   vrrp_skip_check_adv_addr

#  vrrp_strict

   vrrp_garp_interval 0

   vrrp_gna_interval 0

}

vrrp_instance VI_1 {

    state MASTER

    interface ens33

    virtual_router_id 1

    priority 100

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.10.172

    }

}

注释:

vrrp_strict #严格执行VRRP协议规范,此模式不支持节点单播,如果配置了此参数,vip可以漂移到这台服务器,但是ping vip不通,因此需要将此参数去掉

[root@localhost keepalived]# systemctl start keepalived

[root@localhost keepalived]# ip add show dev ens33

ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:ae:7f:64 brd ff:ff:ff:ff:ff:ff

    inet 192.168.10.101/24 brd 172.16.16.255 scope global ens33

       valid_lft forever preferred_lft forever

    inet 192.168.10.172/32 scope global ens33

       valid_lft forever preferred_lft forever

备用服务器的配置

[root@localhost ~]# systemctl stop NetworkManager

[root@localhost ~]# setenforce 0

[root@localhost ~]# systemctl stop firewalld

[root@localhost ~]# cd /etc/keepalived/

[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bak

[root@localhost keepalived]# vi keepalived.conf

global_defs {

   notification_email {

     acassen@firewall.loc

     failover@firewall.loc

     sysadmin@firewall.loc

   }

   notification_email_from Alexandre.Cassen@firewall.loc

   #vrrp_strict

   smtp_server 192.168.200.1

   smtp_connect_timeout 30

   router_id LVS_02

}

vrrp_instance VI_1 {

    state BACKUP

    interface ens33

    virtual_router_id 1

    priority 99

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.10.172

    }

}

使用ping命令测试虚拟ip的连通性

在测试过程中down掉master服务器的网络,观察ping的结果,如果keepalive运行正常,ping的结果不会中断。

LVS+Keepalived高可用性

配置主调度器

主服务器keepalived的安装

[root@localhost ~]# systemctl stop NetworkManager

[root@localhost ~]# setenforce 0

[root@localhost ~]# systemctl stop firewalld

[root@localhost ~]# yum -y install keepalived ipvsadm

[root@localhost ~]# systemctl enable keepalived

主服务器keepalived的配置

[root@localhost ~]# cd /etc/keepalived/

[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bak

[root@localhost keepalived]# vi keepalived.conf

global_defs {

   notification_email {

     acassen@firewall.loc

     failover@firewall.loc

     sysadmin@firewall.loc

   }

   notification_email_from Alexandre.Cassen@firewall.loc

   #vrrp_strict

   smtp_server 192.168.200.1

   smtp_connect_timeout 30

   router_id LVS_01

}

vrrp_instance VI_1 {

    state MASTER

    interface ens33

    virtual_router_id 51

    priority 100

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.10.172

    }

}

virtual_server 192.168.10.172 80 {

    delay_loop 6

    lb_algo rr

    lb_kind DR

    nat_mask 255.255.255.0

!    persistence_timeout 50

    protocol TCP

    real_server 192.168.10.103 80 {

        weight 1

        TCP_CHECK {

            connect_port 80

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

    real_server 192.168.10.104 80 {

        weight 1

        TCP_CHECK {

            connect_port 80

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

}

注释:persistence_timeout 50

这个参数的意义是保持客户端的请求在这个时间段内全部发到同一个真实服务器

主服务器内核参数的配置

[root@localhost ~]# vi /etc/sysctl.conf

在末尾添加:

net.ipv4.conf.all.send_redirects = 0

net.ipv4.conf.default.send_redirects = 0

net.ipv4.conf.ens33.send_redirects = 0

[root@localhost ~]# sysctl -p

开启主服务器的keepalived服务

[root@localhost keepalived]# systemctl start keepalived

[root@localhost keepalived]# ip add show dev ens33

2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether 00:0c:29:ae:7f:64 brd ff:ff:ff:ff:ff:ff

    inet 192.168.10.101/24 brd 172.16.16.255 scope global ens33

       valid_lft forever preferred_lft forever

    inet 192.168.10.172/32 scope global ens33

       valid_lft forever preferred_lft forever

配置从调度器

从调度器keepalived安装

[root@localhost ~]# systemctl stop NetworkManager

[root@localhost ~]# setenforce 0

[root@localhost ~]# systemctl stop firewalld

[root@localhost ~]# yum -y install keepalived ipvsadm

[root@localhost ~]# systemctl enable keepalived

从调度器keepalived的配置

[root@localhost ~]# cd /etc/keepalived/

[root@localhost keepalived]# cp keepalived.conf keepalived.conf.bak

[root@localhost keepalived]# vi keepalived.conf

global_defs {

   notification_email {

     acassen@firewall.loc

     failover@firewall.loc

     sysadmin@firewall.loc

   }

   notification_email_from Alexandre.Cassen@firewall.loc

   #vrrp_strict

   smtp_server 192.168.200.1

   smtp_connect_timeout 30

   router_id LVS_02

}

vrrp_instance VI_1 {

    state BACKUP

    interface ens33

    virtual_router_id 51

    priority 99

    advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

    virtual_ipaddress {

        192.168.10.172

    }

}

virtual_server 192.168.10.172 80 {

    delay_loop 6

    lb_algo rr

    lb_kind DR

    nat_mask 255.255.255.0

!    persistence_timeout 50

    protocol TCP

    real_server 192.168.10.101 80 {

        weight 1

        TCP_CHECK {

            connect_port 80

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

    real_server 192.168.10.102 80 {

        weight 1

        TCP_CHECK {

            connect_port 80

            connect_timeout 3

            nb_get_retry 3

            delay_before_retry 3

        }

    }

}

从服务器内核参数的配置

[root@localhost ~]# vi /etc/sysctl.conf

在末尾添加:

net.ipv4.conf.all.send_redirects = 0

net.ipv4.conf.default.send_redirects = 0

net.ipv4.conf.ens33.send_redirects = 0

[root@localhost ~]# sysctl -p

开启从服务器的keepalived服务

[root@localhost keepalived]# systemctl start keepalived

服务器池配置

web1服务器配置

(1)web1网络的配置

[root@localhost ~]# systemctl stop firewalld

[root@localhost ~]# cd /etc/sysconfig/network-scripts/

[root@localhost network-scripts]# cp ifcfg-lo ifcfg-lo:0

[root@localhost network-scripts]# vi ifcfg-lo:0

DEVICE=lo:0

IPADDR=192.168.10.172

NETMASK=255.255.255.255

ONBOOT=yes

[root@localhost network-scripts]# systemctl restrt network

[root@localhost network-scripts]# vi /etc/rc.local

/sbin/route add -host 192.168.10.172 dev lo:0

[root@localhost network-scripts]# route add -host 192.168.10.172 dev lo:0

(2)httpd服务的安装

[root@localhost ~]# yum -y install httpd

[root@localhost ~]# vi /var/www/html/index.html

test web01

(3)内核参数的设置

[root@localhost ~]# vi /etc/sysctl.conf

net.ipv4.conf.all.arp_ignore = 1

net.ipv4.conf.all.arp_announce = 2

net.ipv4.conf.default.arp_ignore = 1

net.ipv4.conf.default.arp_announce = 2

net.ipv4.conf.lo.arp_ignore = 1

net.ipv4.conf.lo.arp_announce = 2

(4)开启httpd服务

[root@localhost ~]# systemctl start httpd

web2服务器配置

(1)web2网络的配置

[root@localhost ~]# systemctl stop firewalld

[root@localhost ~]# cd /etc/sysconfig/network-scripts/

[root@localhost network-scripts]# cp ifcfg-lo ifcfg-lo:0

[root@localhost network-scripts]# vi ifcfg-lo:0

DEVICE=lo:0

IPADDR=192.168.10.172

NETMASK=255.255.255.255

ONBOOT=yes

[root@localhost network-scripts]# systemctl restrt network

[root@localhost network-scripts]# vi /etc/rc.local

/sbin/route add -host 192.168.10.172 dev lo:0

[root@localhost network-scripts]# route add -host 192.168.10.172 dev lo:0

(2)httpd服务的安装

[root@localhost ~]# yum -y install httpd

[root@localhost ~]# vi /var/www/html/index.html

test web02

(3)内核参数的设置

[root@localhost ~]# vi /etc/sysctl.conf

net.ipv4.conf.all.arp_ignore = 1

net.ipv4.conf.all.arp_announce = 2

net.ipv4.conf.default.arp_ignore = 1

net.ipv4.conf.default.arp_announce = 2

net.ipv4.conf.lo.arp_ignore = 1

net.ipv4.conf.lo.arp_announce = 2

(4)开启httpd服务

[root@localhost ~]# systemctl start httpd

测试LVS+Keepalived高可用性

用客户端访问网站

http://192.168.10.172

刷新页面并观察网页的变化

在客户端使用脚本测试

[root@localhost ~]# for i in $(seq 10); do curl http://192.168.10.172  ;done

注意事项

(1)生产环境中可以使用NFS服务器保证网站代码的一致性,在测试环境中为了观察效果,web服务器池中的网站代码可以不一样,更加便于观察实验效果。

(2)测试计算机不要使用master调度器,在master调度器上访问VIP时,调度器不会将访问的请求调度到web服务器,而是自己尝试解析;在web服务器上测试时只能访问到自己的网页,无法实现调度。所以客户端一定要使用独立的测试计算机,或者使用处于BACKUP状态的调度器。

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