KeepAlived的实现示例

KeepAlived的实现

    HA Cluster配置准备：
        各节点时间必须同步
            ntp（6）, chrony（7）
            1》在centos6上
                ntpdate  172.18.0.1
                vim /etc/ntp.conf
                    server  ip地址 iburst   #与谁的服务址进行同步
                service ntpd start
                chkconfig ntpd on
            2》在centos7上
                ntpdate 172.18.0.1
                vim /etc/chrony.conf
                    server  ip地址 iburst
                systemctl start chronyd
                systemctl enable chronyd
            3》为什么要先同步时间再去修改配置文件？
                因为如果时间相差的太多是不会同步的，所以必须用ntpdate命令将时间先同步后再去修改配置文件。
                ntpdate命令是暴力同步命令，而服务ntpd和chronyd是弱同步，会进行不断的更新。
        确保iptables 及selinux 不会成为阻碍
        各节点之间可通过主机名互相通信（对KeepAlived 并非必须）建议使用/etc/hosts 文件实现
            1》在centos6上
                vim /etc/sysconfig/network
                    HOSTNAME=
                vim  /etc/hosts
                    ip地址  HOSTNAME
                退出重新登录
            2》在centos7上
                hostnamectl set-hostname  HOSTNAME
                vim /etc/hosts
                    ip地址  HOSTNAME
                退出重新登录
            3》测试，ping HOSTNAME
        各节点之间的root 用户可以基于密钥认证的ssh服务完成互相通信（对KA并非必须）
            1》在centos6和centos7上
                生成密钥对
                    ssh-keygen 
                将公钥拷贝给对方
                    ssh-copy-id -i id_rsa.pub HOSTNAME（ip地址）
            2》测试，直接使用ssh 登录
        
    keepalived 安装配置：
        CentOS 6.4+ Base源
        程序环境：
            主配置文件：/etc/keepalived/keepalived.conf
            主程序文件：/usr/sbin/keepalived
            Unit File ：/usr/lib/systemd/system/keepalived.service
            Unit File 的环境配置文件：/etc/sysconfig/keepalived

高可用的ipvs 集群示例

    ! Configuration File for keepalived
    global_defs {
        notification_email {
            root@localhost
        }
        notification_email_from keepalived@localhost
        smtp_server 127.0.0.1
        smtp_connect_timeout 30
        router_id node1
        vrrp_mcast_group4 224.0.100.10
    }
    vrrp_instance VI_1 {
        state MASTER
        interface eth0
        virtual_router_id 6
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 571f97b2
        }
        virtual_ipaddress {
            172.16.0.10/16 dev eth0
        }
        notify_master "/etc/keepalived/notify.sh master"
        notify_backup "/etc/keepalived/notify.sh backup"
        notify_fault "/etc/keepalived/notify.sh fault"
    }
    virtual_server 172.16.0.10 80 {
        delay_loop 3
        lb_algo rr
        lb_kind DR
        protocol TCP
        sorry_server 127.0.0.1 80
        real_server 172.16.0.11 80 {
            weight 1
            HTTP_GET {
                url {
                    path /
                    status_code 200
                }
            connect_timeout 1
            nb_get_retry 3
            delay_before_retry 1
            }
        }
    real_server 172.16.0.12 80 {
        weight 1
        HTTP_GET {
            url {
                path /
                status_code 200
            }
        connect_timeout 1
        nb_get_retry 3
        delay_before_retry 1
        }
        }
    }

双主模式的lvs集群，拓扑、实现过程

    其中一个节点：
    ! Configuration File for keepalived
    global_defs {
        notification_email {
            root@localhost
        }
        notification_email_from kaadmin@localhost
        smtp_server 127.0.0.1
        smtp_connect_timeout 30
        router_id node1
        vrrp_mcast_group4 224.0.100.100
    }
    vrrp_instance VI_1 {
        state MASTER
        interface eth0
        virtual_router_id 6
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass f1bf7fde
        }
        virtual_ipaddress {
                172.16.0.80/16 dev eth0 label eth0:0
        }
        track_interface {
                eth0
        }
        notify_master "/etc/keepalived/notify.sh master"
        notify_backup "/etc/keepalived/notify.sh backup"
        notify_fault "/etc/keepalived/notify.sh fault"
    }
    vrrp_instance VI_2 {
        state BACKUP
        interface eth0
        virtual_router_id 8
        priority 98
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass f2bf7ade
        }
        virtual_ipaddress {
            172.16.0.90/16 dev eth0 label eth0:1
        }
        track_interface {
            eth0
        }
        notify_master "/etc/keepalived/notify.sh master"
        notify_backup "/etc/keepalived/notify.sh backup"
        notify_fault "/etc/keepalived/notify.sh fault"
    }
    virtual_server fwmark 3 {
        delay_loop 2
        lb_algo rr
        lb_kind DR
        nat_mask 255.255.0.0
        protocol TCP
        sorry_server 127.0.0.1 80
        real_server 172.16.0.11 80 {
            weight 1
            HTTP_GET {
                url {
                    path /
                    status_code 200
                }
                connect_timeout 2
                nb_get_retry 3
                delay_before_retry 3
            }
        }
    real_server 172.16.0.12 80 {
        weight 1
        HTTP_GET {
            url {
                path /
                status_code 200
            }
            connect_timeout 2
            nb_get_retry 3
            delay_before_retry 3
        }
        }
    }

keepalived 调用脚本进行资源监控

    keepalived 调用外部的辅助脚本进行资源监控，并根据监控的结果状态能实现优先动态调整。
    vrrp_script:
        自定义一个资源监控脚本或服务监控脚本，脚本可以返回成功或失败的值，vrrp实例脚本根据脚本返回的状态修改调度。
        公共定义，可被多个实例调用，定义在vrrp 实例之外。
    track_script:
        调用vrrp_script 定义的脚本去监控资源，定义在实例之内，调用事先定义的vrrp_script。
        调用跟踪脚本，使当前调度器减去一定的数值，使其优化级低于master配置。
    分两步：(1) 先定义一个脚本；(2)调用此脚本
        vrrp_script <SCRIPT_NAME> {
            script ""
            interval INT
            weight -INT
        }
        track_script {
            SCRIPT_NAME_1
            SCRIPT_NAME_2
        }

高可用的nginx

    ! Configuration File for keepalived
    global_defs {
        notification_email {
            root@localhost
        }
        notification_email_from keepalived@localhost
        smtp_server 127.0.0.1
        smtp_connect_timeout 30
        router_id node1
        vrrp_mcast_group4 224.0.100.100
    }
    vrrp_script chk_down {
        script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
        interval 1
        weight -20
    }
    vrrp_script chk_nginx {
        script "killall -0 nginx && exit 0 || exit 1"
        interval 1
        weight -20
        fall 2      #2 次检测失败为失败
        rise 1      #1 次检测成功为成功
    }
    vrrp_instance VI_1 {
        state MASTER
        interface eth0
        virtual_router_id 14
        priority 100
        advert_int 1
        authentication {
            auth_type PASS
            auth_pass 571f97b2
        }
        virtual_ipaddress {
            172.18.0.93/16 dev eth0
        }
        track_script {
            chk_down
            chk_nginx
        }
        notify_master "/etc/keepalived/notify.sh master"
        notify_backup "/etc/keepalived/notify.sh backup"
        notify_fault "/etc/keepalived/notify.sh fault"
    }

同步组

    LVS NAT模型VIP 和DIP需要同步，需要同步组
    vrrp_sync_group VG_1 {
        group {
            VI_1    # name of vrrp_instance (below)
            VI_2    # One for each moveable IP.
        }
    }
    vrrp_instance VI_1 {
        eth0
        vip
    }
    vrrp_instance VI_2 {
        eth1
        dip
    }