Redis+Keepalived高可用環境部署記錄

散盡浮華發表於2018-05-07

Keepalived 實現VRRP（虛擬路由冗餘）協議，從路由級別實現VIP切換，可以完全避免類似heartbeat腦裂問題，可以很好的實現主從、主備、互備方案，尤其是無狀態業務，有狀態業務就需要額外花些功夫了。既然Mysql可以使用Keepalived很好的做到主從切換，那麼Redis自然可以使用這種方式實現高可用。

Redis主從實現完全沒有Mysql成熟，僅僅是可用而已，經過測試主從也不是那麼完全不靠譜，主要問題在於同步連線斷開之後需要重新全量同步，如果頻繁進行會對主服務帶來很大效能影響。但現實中主從機器往往要求放在一個機櫃同一臺交換裝置下，網路閃斷情況極低；再者主從同步在同步數量量大情況下，需要將快取區調得足夠大，不然也容易造成連線斷開。
實現切換邏輯如下：A和B兩臺機器
1）A 、B機器依次啟動，A機作為主、B機為從。
2）主A機掛掉，B機接管業務並作為主。
3）A機起來，作為從SLAVEOF B。
4）B機掛掉，A機再切回主。

在Keepalived 有兩個角色：Master(一個)、Backup（多個），如果設定一個為Master，但Master掛了後再起來，必然再次業務又一次切換，這對於有狀態服務是不可接受的。解決方案就是兩臺機器都設定為Backup，而且優先順序高的Backup設定為nopreemt 不搶佔。

部署記錄：

0）伺服器資訊

192.168.10.205    redis-master     需要安裝redis(3.2.0版本)、keepalived(1.3.2版本)
192.168.10.206    redis-slave      需要安裝redis(3.2.0版本)、keepalived(1.3.2版本)
192.168.10.230    VIP

關閉兩個節點機器的iptables和selinux（兩個節點上都要操作）
[root@redis-master ~]# /etc/init.d/iptables stop
[root@redis-master ~]# vim /etc/sysconfig/selinux
......
SELINUX=disabled
[root@redis-master ~]# setenforce 0
[root@redis-master ~]# getenforce 
Permissive

1）安裝redis服務及主從配置（兩個節點機都要操作）

[root@redis-master ~]# cd /usr/local/src/
[root@redis-master src]# wget http://download.redis.io/releases/redis-3.2.0.tar.gz
[root@redis-master src]# tar -zvxf redis-3.2.0.tar.gz
[root@redis-master src]# cd redis-3.2.0
[root@redis-master redis-3.2.0]# make

新增相關檔案及命令
[root@redis-master redis-3.2.0]# mkdir -p /usr/local/redis/bin/ 
[root@redis-master redis-3.2.0]# cd src
[root@redis-master src]# cp redis-benchmark redis-check-aof redis-check-rdb redis-cli redis-server redis-sentinel /usr/local/redis/bin/
[root@redis-master src]# cd ../
[root@redis-master redis-3.2.0]# cp redis.conf /etc/

新增redis啟動指令碼
[root@redis-master redis-3.2.0]# vim /etc/init.d/redis 
#!/bin/bash
#chkconfig: 2345 10 90
#description: Start and Stop redis

REDISPORT=6379

EXEC=/usr/local/redis/bin/redis-server

REDIS_CLI=/usr/local/redis/bin/redis-cli 

PIDFILE=/var/run/redis.pid

CONF="/etc/redis.conf"

case "$1" in

start)

if [ -f $PIDFILE ]

then

echo "$PIDFILE exists, process is already running or crashed"

else

echo "Starting Redis server..."

$EXEC $CONF

fi

if [ "$?"="0" ]

then

echo "Redis is running..."

fi

;;

stop)

if [ ! -f $PIDFILE ]

then

echo "$PIDFILE does not exist, process is not running"

else

PID=$(cat $PIDFILE)

echo "Stopping ..."

$REDIS_CLI -p $REDISPORT SHUTDOWN

while [ -x ${PIDFILE} ]

do

echo "Waiting for Redis to shutdown ..."

sleep 1

done

echo "Redis stopped"

fi

;;

restart|force-reload)

${0} stop

${0} start

;;

*)

echo "Usage: /etc/init.d/redis {start|stop|restart|force-reload}" >&2

exit 1

esac

新增執行許可權
[root@redis-master redis-3.2.0]# chmod 755 /etc/init.d/redis

設定開機自啟動
[root@redis-master redis-3.2.0]# chkconfig --add redis
[root@redis-master redis-3.2.0]# chkconfig redis on

建立redis狀態日誌
[root@redis-master redis-3.2.0]# mkdir /var/log/redis/
[root@redis-master redis-3.2.0]# touch /var/log/redis/redis.log

redis主從配置（先看下redis-master主節點的配置）
[root@redis-master redis-3.2.0]# vim /etc/redis.conf
.......
port 6379
.......
daemonize yes              #這個修改為yes
.......
bind 0.0.0.0               #繫結的主機地址。說明只能通過這個ip地址連線本機的redis。最好繫結0.0.0.0；注意這個不能配置成127.0.0.1，否則複製會失敗！用0.0.0.0或者本機ip地址都可以
.......
pidfile /var/run/redis.pid
.......
logfile /var/log/redis/redis.log
.......
dir  /var/redis/redis      #redis資料目錄
....... 
appendonly yes              #啟用AOF持久化方式
appendfilename "appendonly.aof"       #AOF檔案的名稱，預設為appendonly.aof
appendfsync everysec        #每秒鐘強制寫入磁碟一次，在效能和持久化方面做了很好的折中，是受推薦的方式。
.....
save 900 1                 #啟用RDB快照功能，預設就是啟用的
save 300 10
save 60 10000              ＃即在多少秒的時間內，有多少key被改變的資料新增到.rdb檔案裡
.......
slave-serve-stale-data yes    #預設就會開啟
slave-read-only yes
......
dbfilename dump.rdb       ＃快照檔名稱
......

另一個從節點redis-slave的redis.conf配置和上面基本差不多，只是多了下面一行配置：
slaveof 192.168.10.205 6379

接著建立redis的資料目錄
[root@redis-master redis-3.2.0]# mkdir -p /var/redis/redis

然後啟動兩個節點的redis服務
[root@redis-master redis-3.2.0]# /etc/init.d/redis start
Starting Redis server...
Redis is running...
[root@redis-master redis-3.2.0]# lsof -i:6379
COMMAND     PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
redis-ser 17265 root    4u  IPv4  59068      0t0  TCP *:6379 (LISTEN)

2）Keepalived安裝（兩個節點機都要操作）

[root@redis-master ~]# yum -y install openssl openssl-devel
[root@redis-master ~]# cd /usr/local/src/
[root@redis-master src]# wget http://www.keepalived.org/software/keepalived-1.4.0.tar.gz
[root@redis-master src]# tar -zvxf keepalived-1.4.0.tar.gz
[root@redis-master src]# cd keepalived-1.4.0
[root@redis-master keepalived-1.4.0]# ./configure && make && make install

檔案配置
[root@redis-master keepalived-1.4.0]# mkdir /etc/keepalived
[root@redis-master keepalived-1.4.0]# mkdir /usr/local/keepalived/scripts/ -p
[root@redis-master keepalived-1.4.0]# cp /usr/local/src/keepalived-1.4.0/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
[root@redis-master keepalived-1.4.0]# cp /usr/local/src/keepalived-1.4.0/keepalived/etc/init.d/keepalived /etc/init.d/
[root@redis-master keepalived-1.4.0]# cp /usr/local/sbin/keepalived /usr/sbin
[root@redis-master keepalived-1.4.0]# cp /usr/local/src/keepalived-1.4.0/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

設定開機啟動
[root@redis-master keepalived-1.4.0]# chmod +x /etc/init.d/keepalived
[root@redis-master keepalived-1.4.0]# chkconfig --add keepalived
[root@redis-master keepalived-1.4.0]# chkconfig keepalived on

redis主從配置簡單說明

redis的主從複製實現簡單卻功能強大，其具有以下特點：
1）一個master支援多個slave連線，slave可以接受其他slave的連線
2）主從同步時，master和slave都是非阻塞的

redis主從複製可以用來：
1）data redundancy（資料冗餘）
2）slave作為master的擴充套件，提供一些read-only的服務
3）可以將資料持久化放在slave做，從而提升master效能

通過簡單的配置slave（master端無需配置），使用者就能使用redis的主從複製，即只需在slave端的redis.conf檔案中配置下面一行：
slaveof <masterip> <masterport>
表示該redis服務作為slave，masterip和masterport分別為master 的ip和port

其他配置：
masterauth <master-password>
如果master設定了安全密碼，則此處設定為相應的密碼

slave-serve-stale-data yes  當slave丟失master或者同步正在進行時，如果發生對slave的服務請求：
slave-serve-stale-data設定為yes則slave依然正常提供服務
slave-serve-stale-data設定為no則slave返回client錯誤："SYNC with master in progress"

repl-ping-slave-period 10
slave傳送PINGS到master的時間間隔

repl-timeout 60
IO超時時間

3）redis+keepalived配置

a）先進行redis-master主節點的高可用配置
[root@redis-master ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@redis-master ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
  router_id redis-master
}

vrrp_script chk_redis {
  script "/usr/local/keepalived/scripts/redis_check.sh 127.0.0.1 6379"        #監控指令碼  
  interval 2                                    #監控時間
  timeout 2                                     #超時時間
  fall 3
}

vrrp_instance redis {
  state BACKUP                              
  interface eth0
  lvs_sync_daemon_interface eth0
  virtual_router_id 202
  priority 150                              #權重值                  
  nopreempt                                 #nopreempt：設定不搶佔，這裡只能設定在state為backup的節點上，而且這個節點的優先順序必須比另外節點的高
  advert_int 1

  authentication {                          #all node must same              
    auth_type PASS                            #加密    
    auth_pass 1111                            #密碼 
  }

  virtual_ipaddress {
    192.168.10.230                            #VIP地址                  
  }

  track_script {
    chk_redis
  }

notify_master "/usr/local/keepalived/scripts/redis_master.sh 127.0.0.1 192.168.10.206 6379"
notify_backup "/usr/local/keepalived/scripts/redis_backup.sh 127.0.0.1 192.168.10.206 6379"
notify_fault /usr/local/keepalived/scripts/redis_fault.sh
notify_stop /usr/local/keepalived/scripts/redis_stop.sh
}

b）接著進行redis-slave從節點的高可用配置
[root@redis-slave ~]# cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak
[root@redis-slave ~]# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived

global_defs {
  router_id redis-slave
}

vrrp_script chk_redis{
  script "/usr/local/keepalived/scripts/redis_check.sh 127.0.0.1 6379"                            
  interval 2                                     
  timeout 2                                     
  fall 3                                    
}

vrrp_instance redis {
  state BACKUP                                     
  interface eth0                                
  lvs_sync_daemon_interface eth0                      
  virtual_router_id 202
  priority  100                               
  nopreempt 
  advert_int 1

  authentication {   
    auth_type PASS                               
    auth_pass 1111                         
  }

  virtual_ipaddress {
    192.168.10.230                                     
  }

  track_script {
  chk_redis
  }

notify_master "/usr/local/keepalived/scripts/redis_master.sh 127.0.0.1 192.168.10.205 6379"
notify_backup "/usr/local/keepalived/scripts/redis_backup.sh 127.0.0.1 192.168.10.205 6379"
notify_fault /usr/local/keepalived/scripts/redis_fault.sh
notify_stop /usr/local/keepalived/scripts/redis_stop.sh
}

c）在redis-master和redis-slave兩個節點機器上都要建立監控指令碼（下面幾個指令碼，在兩個節點上都要同樣配置）
首先配置監控指令碼
[root@redis-master ~]# vim /usr/local/keepalived/scripts/redis_check.sh 
#!/bin/bash
ALIVE=`/usr/local/redis/bin/redis-cli -h $1 -p $2 PING`
LOGFILE="/var/log/keepalived-redis-check.log"
echo "[CHECK]" >> $LOGFILE
date >> $LOGFILE
if [ $ALIVE == "PONG" ]; then :
   echo "Success: redis-cli -h $1 -p $2 PING $ALIVE" >> $LOGFILE 2>&1
    exit 0
else
    echo "Failed:redis-cli -h $1 -p $2 PING $ALIVE " >> $LOGFILE 2>&1
    exit 1
fi

需要注意的是：
以下負責運作的關鍵指令碼：
notify_master /usr/local/keepalived/scripts/redis_master.sh
notify_backup /usr/local/keepalived/scripts/redis_backup.sh
notify_fault /usr/local/keepalived/scripts/redis_fault.sh
notify_stop /usr/local/keepalived/scripts/redis_stop.sh

因為Keepalived在轉換狀態時會依照狀態來呼叫：
當進入Master狀態時會呼叫notify_master
當進入Backup狀態時會呼叫notify_backup
當發現異常情況時進入Fault狀態呼叫notify_fault
當Keepalived程式終止時則呼叫notify_stop

溫馨提示：
以上的keepalived.conf檔案中的切換模式設定為nopreempt，意思是：
不搶佔VIP資源，此種模式要是所有的節點都必須設定為state BACKUP模式！
需要注意無論主備伺服器都需要設定為BACKUP，與以往KeepAlived的配置不同，其目的就是防止主伺服器恢復後重新搶回VIP，導致Redis切換從而影響穩定。

接著在redis-master主節點上建立notity_master與notify_backup指令碼：
[root@redis-master ~]# vim /usr/local/keepalived/scripts/redis_master.sh
#!/bin/bash
REDISCLI="/usr/local/redis/bin/redis-cli -h $1 -p $3"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[master]" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ... " >> $LOGFILE
$REDISCLI SLAVEOF $2 $3 >> $LOGFILE  2>&1

#echo "SLAVEOF $2 cmd can't excute ... " >> $LOGFILE
sleep 10                                               #延遲10秒以後待資料同步完成後再取消同步狀態
echo "Run SLAVEOF NO ONE cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1

[root@redis-master ~]# vim /usr/local/keepalived/scripts/redis_backup.sh
#!/bin/bash
REDISCLI="/usr/local/redis/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[BACKUP]" >> $LOGFILE
date >> $LOGFILE
echo "Being slave...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE 2>&1
$REDISCLI SLAVEOF $2 $3 >> $LOGFILE
sleep 100                                             #延遲100秒以後待資料同步完成後再取消同步狀態
exit(0)

[root@redis-master ~]# vim /usr/local/keepalived/scripts/redis_fault.sh
#!/bin/bash
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[fault]" >> $LOGFILE
date >> $LOGFILE

[root@redis-master ~]# vim /usr/local/keepalived/scripts/redis_stop.sh
#!/bin/bash
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[stop]" >> $LOGFILE
date >> $LOGFILE

[root@redis-master ~]# chmod 755 /usr/local/keepalived/scripts/*.sh
[root@redis-master ~]# ll /usr/local/keepalived/scripts/
total 20
-rwxr-xr-x. 1 root root 283 May  7 07:20 redis_backup.sh
-rwxr-xr-x. 1 root root 360 May  7 07:12 redis_check.sh
-rwxr-xr-x. 1 root root 102 May  7 07:22 redis_fault.sh
-rwxr-xr-x. 1 root root 445 May  7 07:16 redis_master.sh
-rwxr-xr-x. 1 root root 101 May  7 07:23 redis_stop.sh

將redis-master主節點上的上面5個指令碼直接複製到redis-slave節點上即可。
[root@redis-master ~]# rsync -e "ssh -p22" -avpgolr /usr/local/keepalived/scripts/*.sh root@192.168.10.206:/usr/local/keepalived/scripts/

到redis-slave從節點上檢視指令碼：
[root@redis-slave ~]# ll /usr/local/keepalived/scripts/
total 20
-rwxr-xr-x. 1 root root 283 May  7 07:20 redis_backup.sh
-rwxr-xr-x. 1 root root 360 May  7 07:12 redis_check.sh
-rwxr-xr-x. 1 root root 102 May  7 07:22 redis_fault.sh
-rwxr-xr-x. 1 root root 445 May  7 07:16 redis_master.sh
-rwxr-xr-x. 1 root root 101 May  7 07:23 redis_stop.sh

d）設定環境變數（兩個節點上都要設定）
[root@redis-master ~]# vim /etc/profile
......
export PATH=$PATH:/usr/local/redis/bin
[root@redis-master ~]# source /etc/profile

e）啟動兩個節點上的keepalived服務
[root@redis-master ~]# /etc/init.d/keepalived start
Starting keepalived:                                       [  OK  ]
[root@redis-master ~]# ps -ef|grep keepalived
root     32509     1  0 07:29 ?        00:00:00 keepalived -D
root     32510 32509  0 07:29 ?        00:00:00 keepalived -D
root     32512 32509  0 07:29 ?        00:00:00 keepalived -D
root     32515 32512  0 07:29 ?        00:00:00 keepalived -D
root     32517 32515  0 07:29 ?        00:00:00 /bin/bash /usr/local/keepalived/scripts/redis_backup.sh 127.0.0.1 192.168.10.206 6379
root     32529 14122  0 07:29 pts/1    00:00:00 grep keepalived

[root@redis-slave ~]# /etc/init.d/keepalived start
Starting keepalived:                                       [  OK  ]
[root@redis-slave ~]# ps -ef|grep keepalived
root     22277     1  0 07:29 ?        00:00:00 keepalived -D
root     22278 22277  0 07:29 ?        00:00:00 keepalived -D
root     22279 22277  0 07:29 ?        00:00:00 keepalived -D
root     22283 22279  0 07:29 ?        00:00:00 keepalived -D
root     22284 22283  0 07:29 ?        00:00:00 /bin/bash /usr/local/keepalived/scripts/redis_backup.sh 127.0.0.1 192.168.10.205 6379
root     22289 10868  0 07:29 pts/1    00:00:00 grep keepalived

檢視下redis-master主節點，發現vip資源已經有了
[root@redis-master ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:b1:9c:93 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.205/24 brd 192.168.10.255 scope global eth0
    inet 192.168.10.230/32 scope global eth0
    inet6 fe80::5054:ff:feb1:9c93/64 scope link 
       valid_lft forever preferred_lft forever

4）redis+keepalived主從高可用故障切換測試

a）分別啟動redis-master和redis-slave兩個節點的redis和keepalived服務（如上已啟動）
  
b）嘗試通過VIP連線Redis:
[root@redis-master ~]# redis-cli -h 192.168.10.230 INFO|grep role
role:master
[root@redis-master ~]# redis-cli -h 192.168.10.205 INFO|grep role
role:master
[root@redis-master ~]# redis-cli -h 192.168.10.206 INFO|grep role
role:slave
連線成功，Slave也連線上來了。
  
c）嘗試插入一些資料：
[root@redis-master ~]# redis-cli -h 192.168.10.230 SET Hello Redis
OK
  
從VIP讀取資料
[root@redis-master ~]# redis-cli -h 192.168.10.230 GET Hello
"Redis"
  
從redis-master主節點讀取資料
[root@redis-master ~]# redis-cli -h 192.168.10.205 GET Hello
"Redis"
  
從redis-slave從節點讀取資料
[root@redis-master ~]# redis-cli -h 192.168.10.206 GET Hello
"Redis"
  
e）然後開始模擬故障產生：
將redis-master主節點上的redis程式殺死：
[root@redis-master ~]# ps -ef|grep redis
root      4500 14122  0 08:04 pts/1    00:00:00 grep redis
root     17265     1  0 04:00 ?        00:00:07 /usr/local/redis/bin/redis-server 0.0.0.0:6379 
[root@redis-master ~]# kill -9 17265
[root@redis-master ~]# ps -ef|grep redis
root      4514 14122  0 08:04 pts/1    00:00:00 grep redis
  
檢視redis-master主節點上的Keepalived日誌
[root@redis-master ~]# tail -f /var/log/keepalived-redis-state.log
OK
[master]
Mon May  7 07:29:17 CST 2018
Being master....
Run SLAVEOF cmd ...
OK Already connected to specified master
Run SLAVEOF NO ONE cmd ...
OK
[fault]
Mon May  7 08:05:00 CST 2018
  
同時redis-slave從節點上的日誌顯示：
[root@redis-slave ~]# tail -f /var/log/keepalived-redis-state.log
Being slave....
Run SLAVEOF cmd ...
OK
[master]
Mon May  7 08:05:02 CST 2018
Being master....
Run SLAVEOF cmd ...
OK Already connected to specified master
Run SLAVEOF NO ONE cmd ...
OK
  
然後我們可以發現，redis-slave從節點已經接管服務，並且擔任Master的角色了。
redis-slave從節點上已經接管過來VIP資源了（大概需要等待2秒左右的時間，vip資源就切過來了）
[root@redis-slave ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:dd:84:6b brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.206/24 brd 192.168.10.255 scope global eth0
    inet 192.168.10.230/32 scope global eth0
    inet6 fe80::5054:ff:fedd:846b/64 scope link
       valid_lft forever preferred_lft forever
  
[root@redis-slave ~]# redis-cli -h 192.168.10.230 INFO|grep role
role:master
[root@redis-slave ~]# redis-cli -h 192.168.10.205 INFO|grep role
Could not connect to Redis at 192.168.10.205:6379: Connection refused
[root@redis-slave ~]# redis-cli -h 192.168.10.206 INFO|grep role
role:master
  
=======================================================================
然後再恢復redis-master主節點的redis程式
[root@redis-master ~]# /etc/init.d/redis start
/var/run/redis.pid exists, process is already running or crashed
Redis is running...
[root@redis-master ~]# rm -f /var/run/redis.pid
[root@redis-master ~]# /etc/init.d/redis start
Starting Redis server...
Redis is running...
[root@redis-master ~]# ps -ef|grep redis
root      4969     1  0 08:08 ?        00:00:00 /usr/local/redis/bin/redis-server 0.0.0.0:6379 
root      4977  4976  0 08:08 ?        00:00:00 /bin/bash /usr/local/keepalived/scripts/redis_backup.sh 127.0.0.1 192.168.10.206 6379
root      4987 14122  0 08:08 pts/1    00:00:00 grep redis
[root@redis-master ~]# lsof -i:6379
COMMAND    PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
redis-ser 4969 root    4u  IPv4  93698      0t0  TCP *:6379 (LISTEN)
redis-ser 4969 root    6u  IPv4  93709      0t0  TCP 192.168.10.205:43299->192.168.10.206:6379 (ESTABLISHED)
  
檢視redis-master上的Keepalived日誌
[root@redis-master ~]# tail -f /var/log/keepalived-redis-state.log
OK Already connected to specified master
Run SLAVEOF NO ONE cmd ...
OK
[fault]
Mon May  7 08:05:00 CST 2018
[BACKUP]
Mon May  7 08:08:34 CST 2018
Being slave....
Run SLAVEOF cmd ...
OK
  
檢視redis-slave上的Keepalived日誌
[root@redis-slave ~]# tail -f /var/log/keepalived-redis-state.log
Being slave....
Run SLAVEOF cmd ...
OK
[master]
Mon May  7 08:05:02 CST 2018
Being master....
Run SLAVEOF cmd ...
OK Already connected to specified master
Run SLAVEOF NO ONE cmd ...
OK
  
[root@redis-master ~]# redis-cli -h 192.168.10.230 INFO|grep role
role:master
[root@redis-master ~]# redis-cli -h 192.168.10.205 INFO|grep role
role:slave
[root@redis-master ~]# redis-cli -h 192.168.10.206 INFO|grep role
role:master
  
發現redis-master的redis服務再次啟動後，redis-master主節點成為salve角色了，redis-slave從節點還是master角色。
當redis-slave節點當機或redis服務關閉後，redis-master節點再次接管服務成為master角色，如此迴圈~~
  
關閉redis-slave從節點的reids服務
[root@redis-slave ~]# ps -ef|grep redis
root     15407     1  0 04:00 ?        00:00:10 /usr/local/redis/bin/redis-server 0.0.0.0:6379 
root     22900 10868  0 08:11 pts/1    00:00:00 grep redis
[root@redis-slave ~]# kill -9 15407
[root@redis-slave ~]# ps -ef|grep redis
root     22902 10868  0 08:11 pts/1    00:00:00 grep redis
  
檢視redis-slave上的Keepalived日誌
[root@redis-slave ~]# tail -f /var/log/keepalived-redis-state.log
.......
[stop]          //測試時發現，當redis-slave的redis服務關閉後，還需要重啟或關閉keepalived，才能將vip資源漂到redis-master節點上，所以日誌裡也就會出現這個stop資訊
Mon May  7 09:25:03 CST 2018
[BACKUP]
Mon May  7 09:25:04 CST 2018
Being slave....
Run SLAVEOF cmd ...
OK
 
檢視redis-master上的Keepalived日誌
[root@redis-master ~]# tail -f /var/log/keepalived-redis-state.log
.......
[master]
Mon May  7 09:25:03 CST 2018
Being master....
Run SLAVEOF cmd ...
OK Already connected to specified master
Run SLAVEOF NO ONE cmd ...
OK
 
檢視redis-master，發現VIP資源已經接管過來了（如果沒有按時切過來的話，只需重啟或關閉redis-slave節點那邊的keepalived服務即可）
[root@redis-master ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:b1:9c:93 brd ff:ff:ff:ff:ff:ff
    inet 192.168.10.205/24 brd 192.168.10.255 scope global eth0
    inet 192.168.10.230/32 scope global eth0
    inet6 fe80::5054:ff:feb1:9c93/64 scope link
       valid_lft forever preferred_lft forever
  
[root@redis-master ~]# redis-cli -h 192.168.10.230 INFO|grep role
role:master
[root@redis-master ~]# redis-cli -h 192.168.10.205 INFO|grep role
role:master
[root@redis-master ~]# redis-cli -h 192.168.10.206 INFO|grep role
Could not connect to Redis at 192.168.10.206:6379: Connection refused
  
發現redis-maste節點已經轉變為master角色了。
  
同樣，當reids-slave節點的redis服務重新啟動後，它將成為slave角色。
[root@redis-slave ~]# /etc/init.d/redis start
/var/run/redis.pid exists, process is already running or crashed
Redis is running...
[root@redis-slave ~]# rm -f /var/run/redis.pid
[root@redis-slave ~]# /etc/init.d/redis start
Starting Redis server...
Redis is running...
[root@redis-slave ~]# lsof -i:6379
COMMAND     PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
redis-ser 23244 root    4u  IPv4 3049509      0t0  TCP *:6379 (LISTEN)
redis-ser 23244 root    6u  IPv4 3049513      0t0  TCP dns.kevin.cn:44931->192.168.10.205:6379 (ESTABLISHED)
  
[root@redis-master ~]# redis-cli -h 192.168.10.230 INFO|grep role
role:master
[root@redis-master ~]# redis-cli -h 192.168.10.205 INFO|grep role
role:master
[root@redis-master ~]# redis-cli -h 192.168.10.206 INFO|grep role
role:slave

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