Redis 虛擬IP切換

在sentinel進(jìn)行切換時(shí)還會(huì)自動(dòng)調(diào)用一個(gè)腳本（如果設(shè)置的話），做一些自動(dòng)化操作，比如如果我們需要一個(gè)虛擬IP永遠(yuǎn)飄在Master上（這個(gè)VIP可不是被應(yīng)用用來(lái)連接redis 的，用過(guò)的人都知道連接redis sentinel并不依賴于VIP的），那么可以在sentinel配置文件中配置：

sentinel client-reconfig-script mymaster /redis/script/failover.sh

在發(fā)生主從切換，Master發(fā)生變化時(shí)，該腳本會(huì)被sentinel進(jìn)行調(diào)用，調(diào)用的參數(shù)如其配置文件所描述的：

# The following arguments are passed to the script:
#
# <master-name> <role> <state> <from-ip> <from-port> <to-ip> <to-port>
#
# <state> is currently always "failover"
# <role> is either "leader" or "observer"
# 
# The arguments from-ip, from-port, to-ip, to-port are used to communicate
# the old address of the master and the new address of the elected slave
# (now a master).

因此，我們可以在failover.sh中進(jìn)行判斷，如果該腳本所運(yùn)行的主機(jī)IP等于新的Master IP，那么將VIP加上，如果不等于，則該機(jī)器為Slave，就去掉VIP。通過(guò)這種方式進(jìn)行VIP的切換：

#!/bin/sh
_DEBUG="on"
DEBUGFILE=/tmp/sentinel_failover.log
VIP='192.168.2.120'
MASTERIP=${6}
MASK='24'
IFACE='eno33554960'
MYIP=$(ip -4 -o addr show dev ${IFACE}| grep -v secondary| awk '{split($4,a,"/");print a[1]}')

DEBUG () {
        if [ "$_DEBUG" = "on" ]; then
                echo `$@` >>  ${DEBUGFILE}
        fi
}

set -e
DEBUG date 
DEBUG echo $@  
DEBUG echo "Master: ${MASTERIP} My IP: ${MYIP}"
if [ ${MASTERIP} = ${MYIP} ]; then
        if [ $(ip addr show ${IFACE} | grep ${VIP} | wc -l) = 0 ]; then
                /sbin/ip addr add ${VIP}/${MASK} dev ${IFACE}
        DEBUG date
                DEBUG echo "/sbin/ip addr add ${VIP}/${MASK} dev ${IFACE}"
        DEBUG date
        DEBUG echo "IP Arp cleaning: /usr/sbin/arping -q -f -c 1 -A ${VIP} -I ${IFACE}" 
                /usr/sbin/arping -q -f -c 1 -A ${VIP} -I ${IFACE}
        DEBUG date 
        DEBUG echo "IP Failover finished!"
        fi
        exit 0
else
        if [ $(ip addr show ${IFACE} | grep ${VIP} | wc -l) != 0 ]; then
                /sbin/ip addr del ${VIP}/${MASK} dev ${IFACE}
                DEBUG echo "/sbin/ip addr del ${VIP}/${MASK} dev ${IFACE}"
        fi
        exit 0
fi
exit 1

最早這樣的用法是一個(gè)日本人寫(xiě)的blog，請(qǐng)參見(jiàn)：http://blog.youyo.info/blog/2014/05/24/redis-cluster/