keepalive高可用

1. 安装 Keepalived

  • 在主机 C 和 D 上安装 Keepalived：
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    sudo yum install keepalived -y  # CentOS/RHEL
    sudo apt-get install keepalived -y  # Debian/Ubuntu

2. 配置 Keepalived

  • 配置 Keepalived 以管理 VIP 并在故障转移时运行自定义脚本。

  • 在主机 C 上创建/编辑 /etc/keepalived/keepalived.conf：

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    ! Configuration File for keepalived

    global_defs {
            #keepalived机器标识，无特殊作用，一般为机器名
            router_id  LVS_DEVEL
    }


    vrrp_instance VI_1 {
        state MASTER
        interface bond0
        virtual_router_id 51
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass your_password
        }
        virtual_ipaddress {
            192.168.1.100/24 dev bond0
        }
        track_script {
            chk_service
        }
        notify_master "/etc/keepalived/master.sh"
        notify_backup "/etc/keepalived/backup.sh"
        notify_fault "/etc/keepalived/fault.sh"
        nopreempt           # 添加这个参数以防止主机故障恢复后自动切回-防止业务的断层
    }

    vrrp_script chk_service {
        script "/etc/keepalived/check_service.sh"
        interval 2
        weight -20
    }

  • 在主机 D 上创建/编辑 /etc/keepalived/keepalived.conf：

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    ! Configuration File for keepalived

    global_defs {
            #keepalived机器标识，无特殊作用，一般为机器名
            router_id  LVS_DEVEL
    }


    vrrp_instance VI_1 {
        state BACKUP
        interface bond0
        virtual_router_id 51
        priority 50
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass your_password
        }   
        virtual_ipaddress {
            192.168.1.100/24 dev bond0
        }
        track_script {
            chk_service
        }
        notify_master "/etc/keepalived/master.sh"
        notify_backup "/etc/keepalived/backup.sh"
        notify_fault "/etc/keepalived/fault.sh"
    }

    vrrp_script chk_service {
        script "/etc/keepalived/check_service.sh"
        interval 2
        weight -20
    }

  • 192.168.1.100/24 dev bond0 #ip是虚拟ip 这里bond0 是虚拟网卡名称（通过bond技术来让双网卡做冗余-详情看linux双网卡冗余篇）

  • 自行编写以下三个脚本（不是必须）：

    notify_master “/etc/keepalived/master.sh” #选举为master时执行脚本
    notify_backup “/etc/keepalived/backup.sh” #选举为backup时执行脚本
    notify_fault “/etc/keepalived/fault.sh” #故障时执行脚本

3. 编写自定义脚本

  • /etc/keepalived/check_service.sh：用于检查业务服务是否运行
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    #!/bin/bash
    # 检查业务服务是否运行的脚本
    # 假设业务服务名为 "my_service"
    if systemctl status my_service > /dev/null; then
        exit 0
    else
        exit 1
    fi

4. 设置脚本权限

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sudo chmod +x /etc/keepalived/*.sh

5. 启动 Keepalived

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sudo systemctl start keepalived
sudo systemctl enable keepalived

nginx + keepalived 高可用配置参考

扩展

配置多个Virtual Router

在主机A和主机B上分别配置Keepalived
以下是主机A上的配置示例，你需要在主机B上进行类似的配置，但将state字段设置为BACKUP，并调整priority字段。

主机A的Keepalived配置（/etc/keepalived/keepalived.conf)

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! Configuration File for keepalived

# 全局配置
global_defs {
   router_id LVS_DEVEL
}

# 配置虚拟路由器1（服务1）
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass 1111
    }

    virtual_ipaddress {
        192.168.1.140
    }
}

# 配置虚拟路由器2（服务2）
vrrp_instance VI_2 {
    state MASTER
    interface eth0
    virtual_router_id 52
    priority 100
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass 2222
    }

    virtual_ipaddress {
        192.168.1.141
    }
}

主机B的Keepalived配置（/etc/keepalived/keepalived.conf)

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! Configuration File for keepalived

global_defs {
   router_id LVS_DEVEL
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 51
    priority 90
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass 1111
    }

    virtual_ipaddress {
        192.168.1.140
    }
}

vrrp_instance VI_2 {
    state BACKUP
    interface eth0
    virtual_router_id 52
    priority 90
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass 2222
    }

    virtual_ipaddress {
        192.168.1.141
    }
}