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keepalived服务介绍

🕗 发布于 2024-07-22 08:09 linux  运维  

keepalived

Keepalived 是一个用于实现高可用性（HA）和负载均衡的开源工具,用 C 编写的路由软件，特别适用于 Linux 服务器。它通常与 HAProxy 等负载均衡器结合使用，以确保服务的高可用性。Keepalived 主要通过 VRRP（虚拟路由冗余协议）来实现虚拟 IP 地址的故障转移。官网

Keepalived 的主要功能

  • VRRP（Virtual Router Redundancy Protocol）:

    • 通过 VRRP 协议实现高可用性，多个服务器可以共享一个虚拟 IP 地址，保证在主服务器出现故障时，备用服务器能够快速接管虚拟 IP，继续提供服务。

  • 健康检查:

    • Keepalived 可以配置健康检查脚本，定期检测服务的状态。如果检测到服务故障，可以自动进行故障转移。

  • 负载均衡:

    • Keepalived 也可以实现简单的负载均衡，通过配置不同的调度算法将流量分配到多个后端服务器。

工作原理

  • VRRP 是一种网络协议，用于在多个路由器之间实现冗余，以确保当主路由器出现故障时，备用路由器可以迅速接管。Keepalived 使用 VRRP 协议实现虚拟 IP 地址的故障转移。

    • 虚拟路由器：由多个物理路由器组成的一个虚拟路由器组。这个组共享一个虚拟 IP 地址（VIP），这个 VIP 是客户端用来访问服务的地址。
    • 主路由器（Master）：负责处理 VIP 上的所有流量。
    • 备用路由器（Backup）：处于待命状态，当主路由器发生故障时，备用路由器之一会接管 VIP。

Keepalived 的工作流程

  • 初始化：当 Keepalived 启动时，所有配置的 VRRP 实例都会初始化。每个实例会根据配置文件设置* 初始状态（Master 或 Backup）、优先级和虚拟 IP 地址。
  • 发送广告报文：主路由器定期发送 VRRP 广告报文，告知网络中的其他路由器它是主路由器。如果其他路由器在一定时间内没有收到广告报文，它们会认为主路由器失效。
  • 健康检查：Keepalived 会定期运行健康检查脚本。如果主路由器的健康检查失败，Keepalived 会将其状态切换为 Backup，并停止发送广告报文。
  • 故障转移：当备用路由器检测到主路由器的广告报文丢失时，它会根据优先级选举一个新的主路由器，并开始发送广告报文，同时接管虚拟 IP 地址。
  • 恢复：如果主路由器恢复正常，它会重新加入 VRRP 实例。如果它的优先级高于当前的主路由器，它会重新夺回主路由器的角色。

安装配置

实验环境；Ubuntu2404

节点IP
master192.168.200.190
node192.168.200.195

主/备模式
官网文档
这种模式下，有一个主节点（Active）和一个或多个备节点（Passive）。只有主节点处理流量，当主节点出现故障时，备节点接管。

特点：

  • 简单易配置
    故障转移速度快
    资源利用率较低，因为备节点在正常情况下处于待命状态

双节点下载

apt install -y keepalived

systemctl enable --now keepalived

自带配置文件模板

 cat /etc/keepalived/keepalived.conf.sample

配置keepalived.conf

vim /etc/keepalived/keepalived.conf

只需要配置全局和vrrp示例即可

root@master:~# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

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_DEVEL
   vrrp_skip_check_adv_addr
   vrrp_strict
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_instance VI_1 {
    state MASTER
    #设置当前节点的状态，可以是 MASTER 或 BACKUP。MASTER 表示当前节点是主节点
    interface eth0
    #指定用于 VRRP 的网络接口，虚拟机为ens33
    virtual_router_id 51
    #设置 VRRP 实例的唯一标识符。这个 ID 在同一 VRRP 实例中必须唯一
    priority 100
    #设置节点的优先级，值范围是 1 到 254。优先级较高的节点更有可能成为主节点
    advert_int 1
    #设置 VRRP 广告的间隔时间（秒）。主节点每隔此时间广播一次 VRRP 广告
    authentication {
    #配置 VRRP 实例的认证信息，以确保只有授权的节点能参与 VRRP 选举
        auth_type PASS
        #auth_type: 认证类型，这里使用 PASS（简单密码认证）
        auth_pass 1111
        #auth_pass: 认证密码
    }
    virtual_ipaddress {
    #配置要绑定到虚拟路由器的 IP 地址。所有参与此 VRRP 实例的节点共享这些 IP 地址
        192.168.200.16
        192.168.200.17
        192.168.200.18
    }
}

开始配置前需要开启参数；允许将非本地 IP 地址绑定到本地网络接口上。这个参数对于使用虚拟 IP 地址（VIP）和实现高可用性（如 Keepalived）特别重要

echo "net.ipv4.ip_nonlocal_bind=1" |  tee -a /etc/sysctl.conf

sysctl -p

开始配置主节点

root@master:~# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

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_DEVEL
   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 51
    priority 101
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.200.199/24
    }
}

systemctl restart keepalived

配置备用节点

root@node:~# cat /etc/keepalived/keepalived.conf
! Configuration File for keepalived

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_DEVEL
}

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 {
        192.168.200.199/24
    }
}

systemctl restart keepalived

主节点验证查看

root@master:~# 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 noprefixroute
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:5f:fb:01 brd ff:ff:ff:ff:ff:ff
    altname enp2s1
    inet 192.168.200.190/24 brd 192.168.200.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 192.168.200.199/24 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe5f:fb01/64 scope link
       valid_lft forever preferred_lft forever
3: ens34: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:5f:fb:0b brd ff:ff:ff:ff:ff:ff
    altname enp2s2
    inet6 fe80::20c:29ff:fe5f:fb0b/64 scope link
       valid_lft forever preferred_lft forever

虚拟机VIP192.168.200.199已经生成

root@master:~# systemctl status keepalived
● keepalived.service - Keepalive Daemon (LVS and VRRP)
     Loaded: loaded (/usr/lib/systemd/system/keepalived.service; enabled; preset: enabled)
     Active: active (running) since Sun 2024-07-21 11:04:12 UTC; 32s ago
       Docs: man:keepalived(8)
             man:keepalived.conf(5)
             man:genhash(1)
             https://keepalived.org
   Main PID: 3590 (keepalived)
      Tasks: 2 (limit: 4556)
     Memory: 2.0M (peak: 2.1M)
        CPU: 49ms
     CGroup: /system.slice/keepalived.service
             ├─3590 /usr/sbin/keepalived --dont-fork
             └─3592 /usr/sbin/keepalived --dont-fork

Jul 21 11:04:26 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:28 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:30 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:32 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:33 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:34 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:38 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:40 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:43 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!
Jul 21 11:04:44 master Keepalived_vrrp[3592]: (VI_1) received a 1 auth, expecting 0!

node节点ping

root@node:~# ping 192.168.200.199
PING 192.168.200.199 (192.168.200.199) 56(84) bytes of data.
64 bytes from 192.168.200.199: icmp_seq=1 ttl=64 time=0.040 ms
64 bytes from 192.168.200.199: icmp_seq=2 ttl=64 time=0.060 ms
64 bytes from 192.168.200.199: icmp_seq=3 ttl=64 time=1.55 ms
64 bytes from 192.168.200.199: icmp_seq=4 ttl=64 time=0.051 ms
^C
--- 192.168.200.199 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3083ms
rtt min/avg/max/mdev = 0.040/0.426/1.554/0.651 ms

关闭master节点keepalived后查看

root@master:~# systemctl stop keepalived
root@master:~# 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 noprefixroute
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:5f:fb:01 brd ff:ff:ff:ff:ff:ff
    altname enp2s1
    inet 192.168.200.190/24 brd 192.168.200.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe5f:fb01/64 scope link
       valid_lft forever preferred_lft forever
3: ens34: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:5f:fb:0b brd ff:ff:ff:ff:ff:ff
    altname enp2s2
    inet6 fe80::20c:29ff:fe5f:fb0b/64 scope link
       valid_lft forever preferred_lft forever

IP由node节点接管

root@node:~# 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 noprefixroute
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:8b:b8:b3 brd ff:ff:ff:ff:ff:ff
    altname enp2s1
    inet 192.168.200.195/24 brd 192.168.200.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 192.168.200.199/24 scope global secondary ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe8b:b8b3/64 scope link
       valid_lft forever preferred_lft forever
3: ens34: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:8b:b8:bd brd ff:ff:ff:ff:ff:ff
    altname enp2s2
    inet6 fe80::20c:29ff:fe8b:b8bd/64 scope link
       valid_lft forever preferred_lft forever

master节点恢复后再次接管，因为优先级高

root@master:~# systemctl restart keepalived
root@master:~# 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 noprefixroute
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:5f:fb:01 brd ff:ff:ff:ff:ff:ff
    altname enp2s1
    inet 192.168.200.190/24 brd 192.168.200.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet 192.168.200.199/24 scope global secondary ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe5f:fb01/64 scope link
       valid_lft forever preferred_lft forever
3: ens34: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:5f:fb:0b brd ff:ff:ff:ff:ff:ff
    altname enp2s2
    inet6 fe80::20c:29ff:fe5f:fb0b/64 scope link
       valid_lft forever preferred_lft forever

但是这种情况下服务会中断一点时间，因为master节点恢复后备用节点将会把IP给主节点，而不是备用节点一直接管，用户会感到卡顿一下


原文地址：https://blog.csdn.net/m0_56363537/article/details/140534910

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