keepalived应用

小卓笔记2025-03-20 2:30

Keepalived 是一个基于 VRRP（虚拟路由冗余协议）实现的高可用解决方案，常用于构建高可用性的服务器集群，特别是在负载均衡场景中，可确保服务的不间断运行。以下为你详细介绍它：

0主要功能

  • 高可用性：借助 VRRP 协议，Keepalived 能在多台服务器间自动切换，当主服务器出现故障时，备用服务器可迅速接替工作，保障服务的持续可用。
  • 负载均衡：Keepalived 可与 LVS（Linux 虚拟服务器）集成，实现对多台服务器的负载均衡，依据预设的算法将客户端请求分发到不同的服务器上。
  • 健康检查：它能对服务器的健康状况进行检查，实时监测服务器的服务状态，一旦发现服务器异常，就会将其从服务列表中移除，待恢复正常后再添加回来。

Keepalived 的工作原理主要基于 VRRP 协议。VRRP 将多台路由器（或服务器）组成一个虚拟路由器，这个虚拟路由器有一个唯一的虚拟 IP 地址（VIP）。在这个虚拟路由器中，有一个主路由器（Master）和多个备用路由器（Backup）。

  • 主路由器：承担处理客户端请求的任务，同时定期发送 VRRP 通告给备用路由器，告知它们自己的存活状态。
  • 备用路由器：处于监听状态，接收主路由器发送的 VRRP 通告。若在一定时间内未收到通告，备用路由器会认为主路由器出现故障，然后通过选举机制选出新的主路由器，并接管虚拟 IP 地址，继续提供服务。

1环境准备

IP地址 主机名 软件 节点
192.168.72.30 master keepalived, nginx 主节点
192.168.72.32 backup keepalived, nginx 从节点
192.168.72.100 Vip地址

1.1前期准备

1.1.1修改IP

#master

root@master \~# nmcli c modify ens160 ipv4.method manual ipv4.addresses 192.168.33.30/24 ipv4.gateway 192.168.33.30 ipv4.dns 223.5.5.5 connection.autoconnect yes

root@master \~# nmcli c up ens160

#backup

root@master \~# nmcli c modify ens160 ipv4.method manual ipv4.addresses 192.168.33.30/24 ipv4.gateway 192.168.33.30 ipv4.dns 223.5.5.5 connection.autoconnect yes

root@master \~# nmcli c up ens160

1.1.2关闭防火墙

root@master \~# systemctl stop firewalld

root@backup \~# systemctl stop firewalld

1.1.3安装nginx服务

#master

root@master \~# systemctl stop firewalld

root@master \~# mount /dev/sr0 /mnt

mount: /mnt: WARNING: source write-protected, mounted read-only.

root@master \~# dnf install nginx -y

Updating Subscription Management repositories.

Unable to read consumer identity

This system is not registered with an entitlement server. You can use "rhc" or "subscription-manager" to register.

BaseOS 757 kB/s | 2.7 kB 00:00

AppStream 1.3 MB/s | 3.2 kB 00:00

baseos 2.7 MB/s | 2.7 kB 00:00

appstream 3.1 MB/s | 3.2 kB 00:00

Dependencies resolved.

=================================================

Package Arch Version Repo Size

=================================================

Installing:

nginx x86_64 2:1.20.1-20.el9 AppStream 40 k

Installing dependencies:

nginx-core

x86_64 2:1.20.1-20.el9 AppStream 574 k

Transaction Summary

=================================================

Install 2 Packages

Total size: 614 k

Installed size: 1.7 M

Downloading Packages:

Running transaction check

Transaction check succeeded.

Running transaction test

Transaction test succeeded.

Running transaction

Preparing : 1/1

Installing : nginx-core-2:1.20.1-2 1/2

Installing : nginx-2:1.20.1-20.el9 2/2

Running scriptlet: nginx-2:1.20.1-20.el9 2/2

Verifying : nginx-2:1.20.1-20.el9 1/2

Verifying : nginx-core-2:1.20.1-2 2/2

Installed products updated.

Installed:

nginx-2:1.20.1-20.el9.x86_64

nginx-core-2:1.20.1-20.el9.x86_64

Complete!

#backup

root@backup \~# mount /dev/sr0 /mnt

mount: /mnt: WARNING: source write-protected, mounted read-only.

root@backup \~# dnf install nginx -y

Updating Subscription Management repositories.

Unable to read consumer identity

This system is not registered with an entitlement server. You can use "rhc" or "subscription-manager" to register.

BaseOS 1.4 MB/s | 2.7 kB 00:00

AppStream 1.4 MB/s | 3.2 kB 00:00

baseos 2.7 MB/s | 2.7 kB 00:00

appstream 3.1 MB/s | 3.2 kB 00:00

Dependencies resolved.

=============================================

Package

Arch Version Repo Size

=============================================

Installing:

nginx

x86_64 2:1.20.1-20.el9 AppStream 40 k

Installing dependencies:

nginx-core

x86_64 2:1.20.1-20.el9 AppStream 574 k

Transaction Summary

=============================================

Install 2 Packages

Total size: 614 k

Installed size: 1.7 M

Downloading Packages:

Running transaction check

Transaction check succeeded.

Running transaction test

Transaction test succeeded.

Running transaction

Preparing : 1/1

Installing : nginx-core-2:1.20 1/2

Installing : nginx-2:1.20.1-20 2/2

Running scriptlet: nginx-2:1.20.1-20 2/2

Verifying : nginx-2:1.20.1-20 1/2

Verifying : nginx-core-2:1.20 2/2

Installed products updated.

Installed:

nginx-2:1.20.1-20.el9.x86_64

nginx-core-2:1.20.1-20.el9.x86_64

Complete!

#区分页面

root@master \~# echo "hello master" > /usr/share/nginx/html/index.html

root@backup \~# echo "hello backup" > /usr/share/nginx/html/index.html

#启动服务

root@master \~# systemctl start nginx

root@backup \~# systemctl start nginx

#测试

root@master \~# curl 192.168.33.30

hello master

root@backup \~# curl 192.168.33.32

hello backup

2keepalived配置

2.1下载keepalived

#master

root@master \~# dnf install keepalived -y

Updating Subscription Management repositories.

Unable to read consumer identity

This system is not registered with an entitlement server. You can use "rhc" or "subscription-manager" to register.

Last metadata expiration check: 0:08:59 ago on Tue 18 Mar 2025 07:25:43 PM CST.

Dependencies resolved.

=================================================

Package Arch Version Repo Size

=================================================

Installing:

keepalived x86_64 2.2.8-3.el9 AppStream 564 k

Transaction Summary

=================================================

Install 1 Package

Total size: 564 k

Installed size: 1.6 M

Downloading Packages:

Running transaction check

Transaction check succeeded.

Running transaction test

Transaction test succeeded.

Running transaction

Preparing : 1/1

Installing : keepalived-2.2.8-3.el 1/1

Running scriptlet: keepalived-2.2.8-3.el 1/1

Verifying : keepalived-2.2.8-3.el 1/1

Installed products updated.

Installed:

keepalived-2.2.8-3.el9.x86_64

Complete!

#backup

root@backup \~# dnf install keepalived -y

Updating Subscription Management repositories.

Unable to read consumer identity

This system is not registered with an entitlement server. You can use "rhc" or "subscription-manager" to register.

Last metadata expiration check: 0:08:59 ago on Tue 18 Mar 2025 07:25:43 PM CST.

Dependencies resolved.

=============================================

Package Arch Version Repo Size

=============================================

Installing:

keepalived

x86_64 2.2.8-3.el9 AppStream 564 k

Transaction Summary

=============================================

Install 1 Package

Total size: 564 k

Installed size: 1.6 M

Downloading Packages:

Running transaction check

Transaction check succeeded.

Running transaction test

Transaction test succeeded.

Running transaction

Preparing : 1/1

Installing : keepalived-2.2.8- 1/1

Running scriptlet: keepalived-2.2.8- 1/1

Verifying : keepalived-2.2.8- 1/1

Installed products updated.

Installed:

keepalived-2.2.8-3.el9.x86_64

Complete!

2.2配置keepalived

#备份配置文件

root@master \~# rpm -qc keepalived

/etc/keepalived/keepalived.conf

/etc/sysconfig/keepalived

root@master \~# cp /etc/keepalived//keepalived.conf{,.bak}

root@backup \~# rpm -qc keepalived

/etc/keepalived/keepalived.conf

/etc/sysconfig/keepalived

root@backup \~# cp /etc/keepalived//keepalived.conf{,.bak}

#master

root@master \~# cat /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

router_id master

}

vrrp_instance VI_1 {

state MASTER

interface ens160

virtual_router_id 51

priority 100

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.33.100

}

}

#backup

root@backup \~# vim /etc/keepalived/keepalived.conf

root@backup \~# cat /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {

router_id master

}

vrrp_instance VI_1 {

state MASTER

interface ens160

virtual_router_id 51

priority 90

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.33.100

}

}

#启动keepalived服务

root@master \~# systemctl start keepalived

root@backup \~# systemctl start keepalived

#IP查看

root@master \~# ip add

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:29:7b:ad:14 brd ff:ff:ff:ff:ff:ff

altname enp3s0

inet 192.168.33.30/24 brd 192.168.33.255 scope global noprefixroute ens160

valid_lft forever preferred_lft forever

inet 192.168.33.100/32 scope global ens160

valid_lft forever preferred_lft forever

inet6 fe80::20c:29ff:fe7b:ad14/64 scope link noprefixroute

valid_lft forever preferred_lft forever

root@backup \~# ip add

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:29:0f:fe:20 brd ff:ff:ff:ff:ff:ff

altname enp3s0

inet 192.168.33.32/24 brd 192.168.33.255 scope global noprefixroute ens160

valid_lft forever preferred_lft forever

inet6 fe80::20c:29ff:fe0f:fe20/64 scope link noprefixroute

valid_lft forever preferred_lft forever

#暂停服务，虚拟ip消失

root@master \~# systemctl stop keepalived.service

root@master \~# ip add

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:29:7b:ad:14 brd ff:ff:ff:ff:ff:ff

altname enp3s0

inet 192.168.33.30/24 brd 192.168.33.255 scope global noprefixroute ens160

valid_lft forever preferred_lft forever

inet6 fe80::20c:29ff:fe7b:ad14/64 scope link noprefixroute

valid_lft forever preferred_lft forever

root@backup \~# ip add

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:29:0f:fe:20 brd ff:ff:ff:ff:ff:ff

altname enp3s0

inet 192.168.33.32/24 brd 192.168.33.255 scope global noprefixroute ens160

valid_lft forever preferred_lft forever

inet6 fe80::20c:29ff:fe0f:fe20/64 scope link noprefixroute

valid_lft forever preferred_lft forever

实验完成！！！

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