keepalived高可用

1.keepalived是什么

Keepalived是一个开源的高可用性解决方案,用于在Linux系统上实现负载均衡和故障切换。它基于VRRP(虚拟路由冗余协议)协议,可以将多台服务器组成一个虚拟的高可用性集群,提供服务的高可用性和负载均衡。

Keepalived通过在多台服务器之间共享一个虚拟IP地址(VIP)来实现负载均衡和故障切换。当主服务器发生故障时,Keepalived会自动将VIP从主服务器切换到备份服务器上,从而实现服务的高可用性。同时,Keepalived还提供了健康检查和故障检测功能,可以监控服务器的状态,并在发现故障时进行自动切换。

Keepalived可以用于各种网络服务的高可用性和负载均衡,如Web服务器、数据库服务器、邮件服务器等。它具有配置简单、性能高效、可靠稳定等特点,被广泛应用于各种生产环境中。

1.1 VRRP

VRRP(Virtual Router Redundancy Protocol)是一种网络协议,用于提供虚拟路由器的冗余性和故障切换功能。它允许多个路由器(或者称为VRRP节点)组成一个虚拟路由器组,共享一个虚拟IP地址(VIP),并通过选举机制选择其中一个节点作为活动节点,负责接收和处理网络流量。

VRRP的主要目的是提供高可用性和故障切换。当活动节点发生故障或失去可达性时,VRRP会自动将VIP切换到备份节点上,以确保网络流量的连续传输。这个切换过程是无感知的,对网络用户来说是透明的。

VRRP通过使用心跳机制来检测节点的可达性。节点之间会周期性地发送VRRP包,以确保彼此的存活状态。如果一个节点停止发送心跳包,其他节点会检测到,并启动选举过程,选择一个新的活动节点来接管VIP。

VRRP可以应用于各种网络环境,特别是在需要提供高可用性和故障切换的关键网络服务中,如路由器、防火墙、负载均衡器等。它是一种简单而有效的解决方案,可以提高网络的可靠性和稳定性。

1.2 keepalived主要功能

  1. 高可用性:Keepalived可以将多个服务器组成一个虚拟的高可用性集群。当主服务器发生故障时,Keepalived会自动将虚拟IP地址(VIP)切换到备份服务器上,从而实现服务的高可用性。
  2. 负载均衡:Keepalived可以将网络流量均衡地分发到多个服务器上,以提高性能和可扩展性。它支持基于轮询、最小连接数、源IP地址等算法进行负载均衡。
  3. 健康检查:Keepalived提供了健康检查功能,可以定期检测服务器的状态,如CPU负载、内存使用、服务可达性等。如果发现服务器故障或不可用,Keepalived会自动将流量切换到其他健康的服务器上。
  4. 故障检测:Keepalived能够监测服务器的故障情况,如网络连接断开、服务崩溃等。一旦发现故障,Keepalived会立即采取措施,如切换VIP、发送警报通知等。
  5. 配置灵活性:Keepalived提供了灵活的配置选项,可以根据实际需求进行定制。用户可以配置虚拟IP地址、健康检查参数、负载均衡算法等,以满足不同场景的需求。

1.3 keepalived工作原理

在Keepalived中,多个服务器节点组成一个虚拟路由器组,共享一个虚拟IP地址(VIP)。其中一个节点被选举为活动节点,负责接收和处理网络流量,而其他节点则作为备份节点。

活动节点通过周期性地发送VRRP包来宣告自己的存在,并维持VIP的可用性。备份节点会监听VRRP包,并检测活动节点的存活状态。如果备份节点在一定时间内没有收到活动节点的VRRP包,或者检测到活动节点失去可达性,备份节点会启动选举过程。

选举过程中,备份节点会通过发送选举请求(Advertisement)来竞选成为新的活动节点。其他备份节点收到选举请求后,会比较自己的优先级和活动节点的优先级,选择优先级较高的节点作为新的活动节点。选举完成后,新的活动节点会接管VIP,继续处理网络流量。

整个故障转移过程是无感知的,对网络用户来说是透明的。他们只需要将流量发送到VIP,Keepalived会自动将流量转发到当前活动节点。

Keepalived还提供了健康检查功能,可以定期检测服务器的状态,如CPU负载、内存使用、服务可达性等。如果发现服务器故障或不可用,Keepalived会自动将流量切换到其他健康的服务器上。

通过VRRP协议和故障检测机制,Keepalived实现了高可用性和故障转移的功能,确保服务的稳定性和可靠性。它被广泛应用于各种网络服务,如Web服务器、数据库服务器、邮件服务器等。

2. keepalived架构安装

设备IP主要作用
CentOS 8192.168.37.120负载均衡服务器
CentOS 8192.168.37.130负载均衡服务器
CentOS 8192.168.37.140web界面
RedHat 8192.168.37.15web界面

安装keepalived架构之前保证两个web服务器安装了httpd服务和两台负载均衡服务器安装了负载均衡服务

这边用haproxy来做负载均衡服务

这里设置高可用ip(vip)为192.168.37.220

//安装keepalived架构之前给两台负载均衡服务器安装haproxy

//主节点和备节点都要安装keepalived
[root@dr1 ~]# yum -y install keepalived

2.1 keepalived配置

//修改/etc/keepalived/keepalived.conf文件

keepalived配置文件详解:

! Configuration File for keepalived

global_defs {       //全局配置
   notification_email {     //定义报警收件人邮件地址
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc    //定义报警发件人邮箱
   smtp_server 192.168.200.1    //邮箱服务器地址
   smtp_connect_timeout 30      //定义邮箱超时时间
   router_id LVS_DEVEL          //定义路由标识信息,同局域网内唯一
   vrrp_skip_check_adv_addr
   vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {        //定义实例
    state MASTER            //指定keepalived节点的初始状态,可选值为MASTER|BACKUP
    interface eth0          //VRRP实例绑定的网卡接口,用户发送VRRP包
    virtual_router_id 51    //虚拟路由的ID,同一集群要一致
    priority 100            //定义优先级,按优先级来决定主备角色,优先级越大越优先
    nopreempt               //设置不抢占
    advert_int 1            //主备通讯时间间隔
    authentication {        //配置认证
        auth_type PASS      //认证方式,此处为密码
        auth_pass 1111      //同一集群中的keepalived配置里的此处必须一致,推荐使用8位随机数
    }
    virtual_ipaddress {     //配置要使用的VIP地址
        192.168.200.16
    }
}

virtual_server 192.168.200.16 1358 {    //配置虚拟服务器
    delay_loop 6        //健康检查的时间间隔
    lb_algo rr          //lvs调度算法
    lb_kind NAT         //lvs模式
    persistence_timeout 50      //持久化超时时间,单位是秒
    protocol TCP        //4层协议

    sorry_server 192.168.200.200 1358   //定义备用服务器,当所有RS都故障时用sorry_server来响应客户端

    real_server 192.168.200.2 1358 {    //定义真实处理请求的服务器
        weight 1    //给服务器指定权重,默认为1
        HTTP_GET {
            url {
              path /testurl/test.jsp    //指定要检查的URL路径
              digest 640205b7b0fc66c1ea91c463fac6334d   //摘要信息
            }
            url {
              path /testurl2/test.jsp
              digest 640205b7b0fc66c1ea91c463fac6334d
            }
            url {
              path /testurl3/test.jsp
              digest 640205b7b0fc66c1ea91c463fac6334d
            }
            connect_timeout 3       //连接超时时间
            nb_get_retry 3          //get尝试次数
            delay_before_retry 3    //在尝试之前延迟多长时间
        }
    }

    real_server 192.168.200.3 1358 {
        weight 1
        HTTP_GET {
            url {
              path /testurl/test.jsp
              digest 640205b7b0fc66c1ea91c463fac6334c
            }
            url {
              path /testurl2/test.jsp
              digest 640205b7b0fc66c1ea91c463fac6334c
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

主服务器更改配置文件

[root@dr1 keepalived]# cat keepalived.conf 
! Configuration File for keepalived

global_defs {
   router_id haproxy01
}

vrrp_instance VI_1 {
    state MASTER
    interface ens160
    virtual_router_id 85
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456789
    }
    virtual_ipaddress {
        192.168.37.220
    }
}

virtual_server 192.168.37.220 80 {
    delay_loop 6
    lb_algo rr
    lb_kind NAT
    persistence_timeout 50
    protocol TCP

    real_server 192.168.37.120 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.37.130 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@dr1 keepalived]# systemctl start keepalived
[root@dr1 keepalived]# systemctl enable keepalived
Created symlink /etc/systemd/system/multi-user.target.wants/keepalived.service → /usr/lib/systemd/system/keepalived.service.

备服务器更改配置文件

[root@dr2 keepalived]# cat keepalived.conf 
! Configuration File for keepalived

global_defs {
   router_id haproxy02
}

vrrp_instance VI_1 {
    state MASTER
    interface ens160
    virtual_router_id 85
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456789
    }
    virtual_ipaddress {
        192.168.37.220
    }
}

virtual_server 192.168.37.220 80 {
    delay_loop 6
    lb_algo rr
    lb_kind NAT
    persistence_timeout 50
    protocol TCP

    real_server 192.168.37.120 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.37.130 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
[root@dr2 keepalived]# systemctl start keepalived
[root@dr2 keepalived]# systemctl enable keepalived
Created symlink /etc/systemd/system/multi-user.target.wants/keepalived.service → /usr/lib/systemd/system/keepalived.service.

2.2 查看vip

//主服务器查看,在主服务器上
[root@dr1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:29:4c:24 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    inet 192.168.37.120/24 brd 192.168.37.255 scope global noprefixroute ens160
       valid_lft forever preferred_lft forever
    inet 192.168.37.220/32 scope global ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe29:4c24/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
       
//备服务器查看,不在备服务器上
[root@dr2 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:40:3b:b5 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    inet 192.168.37.130/24 brd 192.168.37.255 scope global noprefixroute ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe40:3bb5/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

在这里插入图片描述

访问vip可以实现,并已经实现了负载均衡

2.3 模拟服务器失效

//模拟down机,手动关闭主服务器的keepalived和haproxy
[root@dr1 ~]# systemctl stop keepalived
[root@dr1 ~]# systemctl stop haproxy
[root@dr1 ~]# ss -antl
State      Recv-Q     Send-Q          Local Address:Port           Peer Address:Port     Process     
LISTEN     0          128                   0.0.0.0:22                  0.0.0.0:*                    
LISTEN     0          128                      [::]:22                     [::]:*  
[root@dr1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:29:4c:24 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    inet 192.168.37.120/24 brd 192.168.37.255 scope global noprefixroute ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe29:4c24/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

//备机就有了vip
[root@dr2 ~]# systemctl start haproxy
[root@dr2 ~]# ss -antl
State      Recv-Q     Send-Q          Local Address:Port           Peer Address:Port     Process     
LISTEN     0          2048                  0.0.0.0:80                  0.0.0.0:*                    
LISTEN     0          128                   0.0.0.0:22                  0.0.0.0:*                    
LISTEN     0          2048                  0.0.0.0:8189                0.0.0.0:*                    
LISTEN     0          128                      [::]:22                     [::]:* 
[root@dr2 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:40:3b:b5 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    inet 192.168.37.130/24 brd 192.168.37.255 scope global noprefixroute ens160
       valid_lft forever preferred_lft forever
    inet 192.168.37.220/32 scope global ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe40:3bb5/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

在这里插入图片描述

还是可以访问

2.4 配置keepalived加入监控脚本的配置

//创建脚本
[root@dr1 ~]# mkdir /scripts
[root@dr1 scripts]# cat check_haproxy.sh 
#!/bin/bash

haproxy_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhaproxy\b'|wc -l)
if [ $haproxy_status -eq 0 ];then
    systemctl stop keepalived
fi

//编写配置文件
[root@dr1 keepalived]# vim keepalived.conf 
[root@dr1 keepalived]# cat keepalived.conf 
vrrp_script check_haproxy {
    script "/scripts/check_haproxy.sh"
    interval 1
    weight -20
}

vrrp_instance VI_1 {
    state MASTER
    interface ens160
    virtual_router_id 85
    priority 110
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456789
    }
    virtual_ipaddress {
        192.168.37.220
    }
    track_script {
        check_haproxy
    }
}
...

//重启keepalived服务
[root@dr1 keepalived]# systemctl restart keepalived
[root@dr1 keepalived]# ss -antl
State      Recv-Q     Send-Q         Local Address:Port          Peer Address:Port     Process     
LISTEN     0          2048                 0.0.0.0:80                 0.0.0.0:*                    
LISTEN     0          128                  0.0.0.0:22                 0.0.0.0:*                    
LISTEN     0          2048                 0.0.0.0:8189               0.0.0.0:*                    
LISTEN     0          128                     [::]:22                    [::]:*

//在备机创建脚本
[root@dr2 ~]# mkdir /scripts
[root@dr2 ~]# cd /scripts/
[root@dr2 scripts]# ls
[root@dr2 scripts]# vim notify.sh
[root@dr2 scripts]# cat notify.sh 
#!/bin/bash
case "$1" in
  master)
        haproxy_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhaproxy\b'|wc -l)
        if [ $haproxy_status -lt 1 ];then
            systemctl start haproxy
        fi
  ;;
  backup)
        haproxy_status=$(ps -ef|grep -Ev "grep|$0"|grep '\bhaproxy\b'|wc -l)
        if [ $haproxy_status -gt 0 ];then
            systemctl stop haproxy
        fi
  ;;
  *)
        echo "Usage:$0 master|backup"
  ;;
esac
//编写配置文件
[root@dr2 scripts]# vim /etc/keepalived/keepalived.conf 
[root@dr2 scripts]# cat /etc/keepalived/keepalived.conf 
! Configuration File for keepalived

global_defs {
   router_id haproxy02
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens160
    virtual_router_id 85
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456789
    }
    virtual_ipaddress {
        192.168.37.220
    }
    notify_master "/scripts/notify.sh master 192.168.37.220"
    notify_backup "/scripts/notify.sh backup 192.168.37.220"
}
....
//重启keepalived服务
[root@dr2 scripts]# systemctl restart keepalived
[root@dr2 scripts]# ss -antl
State      Recv-Q     Send-Q         Local Address:Port          Peer Address:Port     Process     
LISTEN     0          2048                 0.0.0.0:8189               0.0.0.0:*                    
LISTEN     0          2048                 0.0.0.0:80                 0.0.0.0:*                    
LISTEN     0          128                  0.0.0.0:22                 0.0.0.0:*                    
LISTEN     0          128                     [::]:22                    [::]:*
模拟down机(手动关闭主机的haproxy服务)
//现在vip
[root@dr1 ~]# ss -antl
State      Recv-Q     Send-Q         Local Address:Port          Peer Address:Port     Process     
LISTEN     0          2048                 0.0.0.0:80                 0.0.0.0:*                    
LISTEN     0          128                  0.0.0.0:22                 0.0.0.0:*                    
LISTEN     0          2048                 0.0.0.0:8189               0.0.0.0:*                    
LISTEN     0          128                     [::]:22                    [::]:* 
[root@dr1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:40:3b:b5 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    inet 192.168.37.130/24 brd 192.168.37.255 scope global noprefixroute ens160
       valid_lft forever preferred_lft forever
    inet 192.168.37.220/32 scope global ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe40:3bb5/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
//备机状态
[root@dr2 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:29:4c:24 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    inet 192.168.37.120/24 brd 192.168.37.255 scope global noprefixroute ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe29:4c24/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@dr2 ~]# ss -antl
State      Recv-Q     Send-Q         Local Address:Port          Peer Address:Port     Process     
LISTEN     0          128                  0.0.0.0:22                 0.0.0.0:*                    
LISTEN     0          128                     [::]:22                    [::]:* 

//vip已被备机占用
[root@dr1 ~]# systemctl stop haproxy
[root@dr1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:40:3b:b5 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    inet 192.168.37.130/24 brd 192.168.37.255 scope global noprefixroute ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe40:3bb5/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@dr1 ~]# ss -antl
State      Recv-Q     Send-Q         Local Address:Port          Peer Address:Port     Process     
LISTEN     0          128                  0.0.0.0:22                 0.0.0.0:*                    
LISTEN     0          128                     [::]:22                    [::]:* 

//备机已经变成主机且自动启动了haproxy
[root@dr2 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens160: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:29:4c:24 brd ff:ff:ff:ff:ff:ff
    altname enp3s0
    inet 192.168.37.120/24 brd 192.168.37.255 scope global noprefixroute ens160
       valid_lft forever preferred_lft forever
    inet 192.168.37.220/32 scope global ens160
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe29:4c24/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@dr2 ~]# ss -antl
State      Recv-Q     Send-Q         Local Address:Port          Peer Address:Port     Process     
LISTEN     0          2048                 0.0.0.0:8189               0.0.0.0:*                    
LISTEN     0          2048                 0.0.0.0:80                 0.0.0.0:*                    
LISTEN     0          128                  0.0.0.0:22                 0.0.0.0:*                    
LISTEN     0          128                     [::]:22                    [::]:*

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