keepalived高可用性介绍

keepalived:

Linux Cluster

LB: lvs, nginx

HA：keepalived, heartbeat, corosync, cman

HP：

分布式存储：HDFS

分布式计算：YARN,

batch: MapReduce

in-memory: spark

stream: storm

keepalived：

Acitve/Passive

lvs: vip, ipvs rules

nginx: vip, nginx service

resource, 高可用资源

HA Service: resources

ntp: network time protocol

vrrp：virtual route redundent protocol

Master/Backup

keepalived：

vrrp协议在Linux主机上以守护进程方式的实现；

能够根据配置文件自动生成ipvs规则；

对各RS做健康状态检测；

组件：

vrrp stack

checkers

ipvs wrapper --> ipvs

配置文件的组成部分：

GLOBAL CONFIGURATION

VRRPD CONFIGURATION

vrrp instance

vrrp synchonization group

LVS CONFIGURATION

HA Cluster配置前提：

1、本机的主机名，要与hostname(uname -n)获得的名称保持一致；

CentOS 6: /etc/sysconfig/network

CentOS 7: hostnamectl set-hostname HOSTNAME

各节点要能互相解析主机名；一般建议通过hosts文件进行解析；

2、各节点时间同步；

3、确保iptables及selinux不会成为服务阻碍；

virtual_ipaddress {

/ brd dev scope label

192.168.200.17/24 dev eth1

192.168.200.18/24 dev eth2 label eth2:1

}

nopreempt：非抢占模式；默认为抢占模式；

lvs-NAT模式配置

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

}

邮件通知方式：

在vi中的主机状态发生改变生发送通知：

# notify scripts, alert as above

notify_master |

notify_backup |

notify_fault |

notify |

smtp_alert

配置示例：

! 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 LVS_DEVEL

vrrp_mcast_group4 224.0.1.118

}

vrrp_script chk_mt {

script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"

interval 1

weight -20

}

vrrp_instance VI_1 {

state MASTER

interface eno16777736

virtual_router_id 144

priority 100

advert_int 1

authentication {

auth_type PASS

auth_pass 84ae57f7f4f6

}

virtual_ipaddress {

172.16.100.88/16 dev eno16777736 label eno16777736:1

}

track_script {

chk_mt

}

notify_master "/etc/keepalived/notify.sh master"

notify_backup "/etc/keepalived/notify.sh backup"

notify_fault "/etc/keepalived/notify.sh fault"

}

virtual_server 172.16.100.88 80 {

delay_loop 6

lb_algo wrr

lb_kind DR

nat_mask 255.255.0.0

protocol TCP

sorry_server 127.0.0.1 80

real_server 172.16.100.6 80 {

weight 1

HTTP_GET {

url {

path /

status_code 200

}

connect_timeout 3

nb_get_retry 3

delay_before_retry 3

}

}

real_server 172.16.100.69 80 {

weight 2

HTTP_GET {

url {

path /

status_code 200

}

connect_timeout 3

nb_get_retry 3

delay_before_retry 3

}

}

}

通知脚本：

#!/bin/bash

# Author: zhanx

# description: An example of notify script

#

vip=172.16.100.88

contact='root@localhost'

notify() {

mailsubject="`hostname` to be $1: $vip floating"

mailbody="`date '+%F %H:%M:%S'`: vrrp transition, `hostname` changed to be $1"

echo $mailbody | mail -s "$mailsubject" $contact

}

case "$1" in

master)

notify master

exit 0

;;

backup)

notify backup

exit 0

;;

fault)

notify fault

exit 0

;;

*)

echo 'Usage: `basename $0` {master|backup|fault}'

exit 1

;;

esac

keepalived：

HTTP_GET

SSL_GET(https)

TCP_CHECK

示例：

HTTP_GET {

url {

path /

status_code 200

}

connect_timeout 3

nb_get_retry 3

delay_before_retry 3

}

TCP_CHECK {

connect_timeout 3

}

HA Services:

nginx