KeepAlived基础介绍

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高可用集群

集群Cluster

集群类型:

LB lvs/nginx(http/upstream, stream/upstream)
HA 高可用性

SPoF: Single Point of Failure

系统可用性的公式:A=MTBF/(MTBF+MTTR)

(0,1), 95%
几个9(指标): 99%, …, 99.999%，99.9999%;

系统故障:

硬件故障:设计缺陷、wear out(损耗)、自然灾害…
软件故障:设计缺陷

提升系统高用性的解决方案之降低MTTR:

手段:冗余redundant
active/passive 主备
active/active 双主
active --> HEARTBEAT --> passive
active <–> HEARTBEAT <–> active

高可用的是“服务”:

HA nginx service:

vip/nginx process[/shared storage]

资源:组成一个高可用服务的“组件”
(1) passive node的数量
(2) 资源切换

shared storage:

NAS:文件共享服务器;
SAN:存储区域网络，块级别的共享

Network partition:网络分区

quorum:法定人数

with quorum: > total/2
without quorum: <= total/2

隔离设备: fence

node:STONITH = Shooting The Other Node In The Head，断电重启
资源:断开存储的连接

TWO nodes Cluster

辅助设备:ping node, quorum disk

Failover:故障切换，即某资源的主节点故障时，将资源转移至其它节点的操作
Failback:故障移回，即某资源的主节点故障后重新修改上线后，将之前已转移至其它节点的资源重新切回的过程
HA Cluster实现方案:

ais:应用接口规范完备复杂的HA集群

RHCS:Red Hat Cluster Suite红帽集群套件
heartbeat
corosync

vrrp协议实现:虚拟路由冗余协议 keepalived

KeepAlived

keepalived:

vrrp协议:Virtual Router Redundancy Protocol

术语:

虚拟路由器:Virtual Router 虚拟路由器标识:VRID(0-255)，唯一标识虚拟路由器
物理路由器:

master:主设备
backup:备用设备
priority:优先级

VIP:Virtual IP
VMAC:Virutal MAC (00-00-5e-00-01-VRID)

通告:心跳，优先级等;周期性
工作方式:抢占式，非抢占式
安全工作:

认证:

无认证
简单字符认证:预共享密钥
MD5

工作模式:

主/备:单虚拟路径器
主/主:主/备(虚拟路径器1)，备/主(虚拟路径器2)

keepalived: vrrp协议的软件实现，原生设计目的为了高可用ipvs服务
功能:

vrrp协议完成地址流动
为vip地址所在的节点生成ipvs规则(在配置文件中预先定义)
为ipvs集群的各RS做健康状态检测
基于脚本调用接口通过执行脚本完成脚本中定义的功能，进而影响集群事务，以此支持nginx、haproxy等服务

组件:

核心组件:

vrrp stack
ipvs wrapper
checkers

控制组件:配置文件分析器
IO复用器
内存管理组件

KeepAlived 组成

KeepAlived组成

KeepAlived基础介绍_ipad

KeepAlived实现

HA Cluster 配置准备:

(1) 各节点时间必须同步

ntp, chrony

(2) 确保iptables及selinux不会成为阻碍
(3) 各节点之间可通过主机名互相通信(对KA并非必须)

建议使用/etc/hosts文件实现

(4) 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)

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

配置文件组件部分:
TOP HIERACHY

GLOBAL CONFIGURATION

Global definitions
Static routes/addresses

VRRPD CONFIGURATION

VRRP synchronization group(s):vrrp同步组
VRRP instance(s):即一个vrrp虚拟路由器

LVS CONFIGURATION

Virtual server group(s)
Virtual server(s):ipvs集群的vs和rs

两台主机，主，从实验

1 selinux ,iptables ,time

在proxy1上

#vim keepalived.conf

! 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 proxy1
   vrrp_mcast_group4 224.1.1.1
}

vrrp_instance VI_1 {
    state MASTER
    interface eth1
    virtual_router_id 66
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        172.18.0.200/16
    }
}

在proxy2上

#vim keepalived.conf

! 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 proxy2  ######
   vrrp_mcast_group4 224.1.1.1
}

vrrp_instance VI_1 {
    state BACKUP  #####
    interface eth1
    virtual_router_id 66
    priority 80  #####
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        172.18.0.200/16
    }
}

实验：启用ka的日志

vim /etc/sysconfig/keepalived

KEEPALIVED_OPTIONS="-D -S 3"

vim /etc/rsyslog.conf

local3.*   /var/log/keepalived.log

重启两个服务

systemctl restart rsyslog.service

systemctl restart keepalived.service

实验：keepalived 实现主主IP

proxy1

vim keepalived.conf

global_defs {
   notification_email {
     root@localhost
   }
   notification_email_from keepalived@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id proxy1
   vrrp_mcast_group4 224.1.1.1
}

vrrp_instance VI_1 {
    state MASTER
    interface eth1
    virtual_router_id 66
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        172.18.0.200/16
    }
}
vrrp_instance VI_2 {
    state BACKUP
    interface eth1
    virtual_router_id 88
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 654321
    }
    virtual_ipaddress {
        172.18.0.201/16
    }
}

proxy2

cat keepalived.conf

! 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 proxy2
   vrrp_mcast_group4 224.1.1.1
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth1
    virtual_router_id 66
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        172.18.0.200/16
    }
}
vrrp_instance VI_2 {
    state MASTER
    interface eth1
    virtual_router_id 88
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 654321
    }
    virtual_ipaddress {
        172.18.0.201/16
    }
}

keepAlived 配置

KeepAlived配置

配置语法:
配置虚拟路由器:

  vrrp_instance <STRING> { 
  .... 
  }

专用参数:

state MASTER|BACKUP:当前节点在此虚拟路由器上的初始状态;
只能有一个是MASTER，余下的都应该为BACKUP
interface IFACE_NAME:绑定为当前虚拟路由器使用的物理接口
virtual_router_id VRID:当前虚拟路由器惟一标识，范围是0-255
priority 100:当前物理节点在此虚拟路由器中的优先级;范围1-254
advert_int 1:vrrp通告的时间间隔，默认1s

authentication { #认证机制 
  auth_type AH|PASS 
  auth_pass <PASSWORD> 仅前8位有效 
} 
virtual_ipaddress { #虚拟IP
  <IPADDR>/<MASK> brd <IPADDR> dev <STRING> scope <SCOPE> label <LABEL>
  192.168.200.17/24 dev eth1 
  192.168.200.18/24 dev eth2 label eth2:1 
} 
track_interface { #配置监控网络接口，一旦出现故障，则转为FAULT状态 实现地址转移 
  eth0 
  eth1
   ... 
}

nopreempt:定义工作模式为非抢占模式
preempt_delay 300:抢占式模式，节点上线后触发新选举操作的延迟时长，默认模式
定义通知脚本:

notify_master |: 当前节点成为主节点时触发的脚本
notify_backup |: 当前节点转为备节点时触发的脚本
notify_fault |: 当前节点转为“失败”状态时触发的脚本
notify |: 通用格式的通知触发机制，一个脚本可完成以上三种状态的转换时的通知

KeepAlived单主配置示例

单主配置示例:

! 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 #主机名，在另一结点为node2 
  vrrp_mcast_group4 224.0.100.100 
}

vrrp_instance VI_1 { 
  state MASTER      #在另一个结点上为BACKUP
  interface eth0 
  virtual_router_id 6       #多个节点必须相同
  priority 100        #在另一个结点上为90 
  advert_int 1        #通告间隔1s
  authentication { 
    auth_type PASS#预共享密钥认证 
    auth_pass 571f97b2 
  } 
  virtual_ipaddress {
    172.18.100.66/16 dev eth0 label eth0:0 
  }
  track_interface { 
    eth0 
  } 
}

KeepAlived双主配置

脚本的调用方法:
在vrrp_instance VI_1 语句块最后面加下面行

notify_master “/etc/keepalived/notify.sh master”
notify_backup “/etc/keepalived/notify.sh backup”
notify_fault “/etc/keepalived/notify.sh fault”

示例通知脚本

#!/bin/bash
# 
contact='root@localhost' 
notify() { 
  mailsubject="$(hostname) to be $1, vip floating"
  mailbody="$(date +'%F %T'): vrrp transition, $(hostname) changed to be $1" 
  echo "$mailbody" | mail -s "$mailsubject" $contact 
}
case $1 in 
master) 
  notify master 
  ;; 
backup) 
  notify backup 
  ;; 
fault) 
  notify fault 
  ;; 
*) 
  echo "Usage: $(basename $0) {master|backup|fault}" 
  exit 1
  ;; 
esac

KeepAlived双主配置
双主模型示例:

! 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 224.0.100.100 
}

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 
  }
} 

  vrrp_instance VI_2 { 
    state BACKUP 
    interface eth0 
    virtual_router_id 8 
    priority 98 
    advert_int 1 
    authentication { 
      auth_type PASS 
      auth_pass 578f07b2 
    } 
    virtual_ipaddress { 
      172.16.0.11/16 dev eth0 
    } 
}

实验：实现状态切换时脚本执行

cat keepalived.conf

! 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 proxy1
   vrrp_mcast_group4 224.1.1.1
}

vrrp_instance VI_1 {
    state MASTER
    interface eth1
    virtual_router_id 66
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        172.18.0.200/16
    }
    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 eth1
    virtual_router_id 88
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 654321
    }
    virtual_ipaddress {
        172.18.0.201/16
    }
     notify_master "/etc/keepalived/notify.sh master"
     notify_backup "/etc/keepalived/notify.sh backup"
     notify_fault "/etc/keepalived/notify.sh fault"
}

KeepAlived支持IPVS

虚拟服务器:

配置参数:

  virtual_server IP port | virtual_server fwmark int { 
    ... 
    real_server { 
      ...
    }
      ... 
  }

常用参数

delay_loop <INT>:检查后端服务器的时间间隔
lb_algo rr|wrr|lc|wlc|lblc|sh|dh:定义调度方法
lb_kind NAT|DR|TUN:集群的类型
persistence_timeout <INT>:持久连接时长
protocol TCP:服务协议，仅支持TCP
sorry_server <IPADDR> <PORT>:所有RS故障时，备用服务器地址
real_server <IPADDR> <PORT>
{
weight <INT> RS权重
notify_up <STRING>|<QUOTED-STRING> RS上线通知脚本
notify_down <STRING>|<QUOTED-STRING> RS下线通知脚本
HTTP_GET|SSL_GET|TCP_CHECK|SMTP_CHECK|MISC_CHEC K { … }:定义当前主机的健康状态检测方法
}

KeepAlived配置检测

HTTP_GET|SSL_GET:应用层检测

  HTTP_GET|SSL_GET { 
    url {
      path <URL_PATH>:定义要监控的URL
      status_code <INT>:判断上述检测机制为健康状态的响应码 
      digest <STRING>:判断为健康状态的响应的内容的校验码 
    }
  connect_timeout <INTEGER>:连接请求的超时时长
  nb_get_retry <INT>:重试次数
  delay_before_retry <INT>:重试之前的延迟时长
  connect_ip <IP ADDRESS>:向当前RS哪个IP地址发起健康状态检测请求 
  connect_port <PORT>:向当前RS的哪个PORT发起健康状态检测请求 
  bindto <IP ADDRESS>:发出健康状态检测请求时使用的源地址 
  bind_port <PORT>:发出健康状态检测请求时使用的源端口
  }

传输层检测 TCP_CHECK

  TCP_CHECK { 
    connect_ip <IP ADDRESS>:向当前RS的哪个IP地址发起健康状态检测请求 
    connect_port <PORT>:向当前RS的哪个PORT发起健 康状态检测请求 
    bindto <IP ADDRESS>:发出健康状态检测请求时使用 的源地址 
    bind_port <PORT>:发出健康状态检测请求时使用的源 端口 
    connect_timeout <INTEGER>:连接请求的超时时长 
  }

单主模型IPVS示例

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

双主模式的lvs集群，拓扑、实现过程;

配置示例(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 
    } 
  }
 }

实验：主主模型实现LVS的DR模型

1 proxy1

cat keepalived.conf

! 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 proxy1
   vrrp_mcast_group4 224.1.1.1
}

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 66
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.27.100/24
    }
    notify_master "/etc/keepalived/notify.sh master"
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault "/etc/keepalived/notify.sh fault"
}
virtual_server 192.168.27.100 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    #persistence_timeout 50
    protocol TCP
    sorry_server 127.0.0.1 80
    real_server 192.168.27.27 80 {
        weight 1
        HTTP_GET {
            url {
              path /
              status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.27.37 80 {
        weight 1
        HTTP_GET {
            url {
              path /
              status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
vrrp_instance VI_2{
    state BACKUP
    interface eth0
    virtual_router_id 88
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.27.200/24
    }
    notify_master "/etc/keepalived/notify.sh master"
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault "/etc/keepalived/notify.sh fault"
}
virtual_server 192.168.27.200 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    #persistence_timeout 50
    protocol TCP
    sorry_server 127.0.0.1 80
    real_server 192.168.27.28 80 {
        weight 1
        HTTP_GET {
            url {
              path /
              status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.27.38 80 {
        weight 1
        HTTP_GET {
            url {
              path /
              status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

2 proxy2

cat keepalived.conf

! 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 proxy2
   vrrp_mcast_group4 224.1.1.1
}

vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 66
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.27.100/24
    }
    notify_master "/etc/keepalived/notify.sh master"
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault "/etc/keepalived/notify.sh fault"
}
virtual_server 192.168.27.100 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    #persistence_timeout 50
    protocol TCP
    sorry_server 127.0.0.1 80
    real_server 192.168.27.27 80 {
        weight 1
        HTTP_GET {
            url {
              path /
              status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.27.37 80 {
        weight 1
        HTTP_GET {
            url {
              path /
              status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}
vrrp_instance VI_2 {
    state MASTER
    interface eth0
    virtual_router_id 88
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.27.200/24
    }
    notify_master "/etc/keepalived/notify.sh master"
    notify_backup "/etc/keepalived/notify.sh backup"
    notify_fault "/etc/keepalived/notify.sh fault"
}
virtual_server 192.168.27.200 80 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    #persistence_timeout 50
    protocol TCP
    sorry_server 127.0.0.1 80
    real_server 192.168.27.28 80 {
        weight 1
        HTTP_GET {
            url {
              path /
              status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.27.38 80 {
        weight 1
        HTTP_GET {
            url {
              path /
              status_code 200
            }
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}

3 rs1和rs2 脚本

cat /root/lvs_dr_rs.sh

#!/bin/bash
#Author:wangxiaochun
#Date:2017-08-13
vip=192.168.27.100
vip2=192.168.27.200
mask='255.255.255.255'
dev=lo:1
dev2=lo:2

case $1 in
start)
    echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
    echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
    echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
    echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce
    ifconfig $dev $vip netmask $mask #broadcast $vip up
    ifconfig $dev2 $vip2 netmask $mask #broadcast $vip up
    #route add -host $vip dev $dev
    echo "The RS Server is Ready!"
    ;;
stop)
    ifconfig $dev down
    ifconfig $dev2 down
    echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
    echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore
    echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce
    echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce
    echo "The RS Server is Canceled!"
    ;;
*) 
    echo "Usage: $(basename $0) start|stop"
    exit 1
    ;;
esac

4 rs1和rs2

cat /etc/httpd/conf.d/vhosts.conf

<virtualhost 192.168.27.100:80>
documentroot /data/web1
<directory /data/web1>
require all granted
</directory>
</virtualhost>

<virtualhost 192.168.27.200:80>
documentroot /data/web2
<directory /data/web2>
require all granted
</directory>
</virtualhost>

5 rs1和rs2

tree /data

/data

├── web1

│?? └── index.html

└── web2

└── index.html

rs1

echo 192.168.27.100 RS1 > /data/web1/index.html

echo 192.168.27.200 RS1 > /data/web1/index.html

rs2

echo 192.168.27.100 RS2 > /data/web1/index.html

echo 192.168.27.200 RS2 > /data/web1/index.html

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:自定义资源监控脚本，vrrp实例根据脚本返回值，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
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 
}

示例:高可用nginx服务

! 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 
}

实验：ka实现nginx高可用性

1 proxy1

cat keepalived.conf

! 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 proxy1
   vrrp_mcast_group4 224.1.1.1
}
vrrp_script chk_down {
        script '[ -f "/etc/keepalived/down" ] && exit 1 || exit 0'
        interval 1
        weight -30
}
vrrp_script chk_nginx {
script "killall -0 nginx && exit 0 || exit 1"
interval 1
weight -30
fall 2 
rise 2 
}
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 66
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.27.100/24
    }
    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"
}

2 proxy2

cat keepalived.conf

! 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 proxy2
   vrrp_mcast_group4 224.1.1.1
}
vrrp_script chk_down {
        script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
        interval 1
        weight -30
}
vrrp_script chk_nginx {
script "killall -0 nginx && exit 0 || exit 1"
interval 1
weight -30
fall 2 
rise 1 
}
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 66
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 123456
    }
    virtual_ipaddress {
        192.168.27.100/24
    }
    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"
}