标签：keepalived配置 redis集群 redis主从复制 redis高可用 redis-sentinel
为上层应用提供高可靠、低延迟、低（无限接近0）数据损失的Redis缓存服务
采用同一网络内的三台主机（可以是物理主机、虚拟机或docker容器），要求三台主机之间都能相互访问，每一台主机上都安装redis-server、redis-sentinel和keepalived。
redis-server负责提供Redis缓存服务，三台主机间的关系是master-slave-slave
redis-sentinel负责提供Redis高可用，三台主机间的关系与redis-server相同
keepalived负责提供VIP地址供上层应用使用，三台主机的关系是master-backup-backup，VIP始终在redis-server master上，保证对上层应用可写可读。
三台主机的冗余度是1，也就是说当有一台主机宕机时另外两台中至少有一台主机可以提供Redis缓存服务
redis-server提供单实例的Redis缓存服务，redis-sentinel能在一台主机挂掉时自动的将某一台可用主机上的redis-server由slave状态切换成master状态。
keepalived通过vrrp_script检测当前主机上的redis-server是否以master状态运行，如果当前主机上的redis-server正在以master状态运行，则将vrrp_instance标记为存活状态，并分配VIP；如果当前主机上的redis-server正在以slave状态运行，则将vrrp_instance标记为错误状态。当某台主机宕机后，其他两台主机上的keepalived会将VIP切换到新的master（当前主机上的redis-server正在以master状态运行）上。
由于keepalived的VIP切换有延迟（大约40ms），因此上层应用不能过分依赖Redis，例如大规模并发性的短时间内向Redis插入大量数据。
如图所示，有三台主机，分别标识为Redis1、Redis2、Redis3，它们的角色和配置等信息如下：
| 主机标识 | Redis1 | Redis2 | Redis3 |
| IP地址 | 192.168.1.241 | 192.168.1.242 | 192.168.1.243 |
| 预设配置 | redis-server master keepalived master | redis-server slave keepalived backup | redis-server slave keepalived backup |
| VIP |
步骤概述
安装：安装redis-server、redis-sentinel、keepalived
配置：配置Redis1、Redis2、Redis3，主要是编辑各个服务的配置文件
启动：先启动redis-server、再启动redis-sentinel、最后自动keepalived
验证：模拟一台主机宕机，主机网络中断，redis-server、redis-sentinel、keepalived三个服务任何一个发生故障的情况。
（1）设定主机名（建议设定为fqdn格式）、同步时间、更改文件描述符最大打开数量、更改内核参数、配置编译环境、配置防火墙在此就不赘述了。
（2）安装redis-server和redis-sentinel
Redis的安装由于只是bin二进制可执行文件和data目录比较重要，因此简化安装如下
# http://download.redis.io/redis-stable.tar.gz wget -c http://download.redis.io/releases/redis-3.0.7.tar.gz tar zxf redis-3.0.7.tar.gz cd redis-3.0.7 make cd \cp redis-3.0.7/src/redis-benchmark /usr/local/sbin/ \cp redis-3.0.7/src/redis-check-aof /usr/local/sbin/ \cp redis-3.0.7/src/redis-check-dump /usr/local/sbin/ \cp redis-3.0.7/src/redis-cli /usr/local/sbin/ \cp redis-3.0.7/src/redis-sentinel /usr/local/sbin/ \cp redis-3.0.7/src/redis-server /usr/local/sbin/ mkdir /etc/redis mkdir -p /data/redis-6379/
（3）安装keepalived
# http://www.keepalived.org/documentation.html wget -c http://www.keepalived.org/software/keepalived-1.2.19.tar.gz tar zxf keepalived-1.2.19.tar.gz cd keepalived-1.2.19 ./configure --prefix=/usr/local/keepalived make make install cp /usr/local/keepalived/sbin/keepalived /usr/sbin/ cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/ mkdir /etc/keepalived
keepalived的配置文件在后面添加
（4）Redis1上的redis-sentinel配置文件
cat >/etc/redis/sentinel.conf<<eof port 26379 dir /tmp sentinel monitor mymaster 192.168.1.241 6379 2 sentinel down-after-milliseconds mymaster 30000 sentinel parallel-syncs mymaster 1 sentinel failover-timeout mymaster 180000 eof
Redis2和Redis3上的redis-sentinel配置文件与Redis1上的redis-sentinel配置文件内容相同。
（5）Redis1上的redis-server的配置文件
cat > /etc/redis/redis-6379.conf <<eof # maxmemory 268435456 maxmemory 256mb daemonize yes pidfile /data/redis-6379/redis-6379.pid port 6379 bind 0.0.0.0 tcp-backlog 511 timeout 0 tcp-keepalive 0 loglevel notice logfile /data/redis-6379/redis.log databases 16 save 900 1 save 300 10 save 60 10000 stop-writes-on-bgsave-error yes rdbcompression yes rdbchecksum yes dbfilename dumpredis-6379.rdb dir /data/redis-6379 slave-serve-stale-data yes slave-read-only yes repl-diskless-sync no repl-diskless-sync-delay 5 # repl-ping-slave-period 10 # repl-timeout 60 repl-disable-tcp-nodelay no # repl-backlog-size 1mb # repl-backlog-ttl 3600 slave-priority 100 # min-slaves-to-write 3 # min-slaves-max-lag 10 appendonly no appendfilename "appendonly.aof" appendfsync everysec no-appendfsync-on-rewrite no auto-aof-rewrite-percentage 100 auto-aof-rewrite-min-size 64mb aof-load-truncated yes lua-time-limit 5000 slowlog-log-slower-than 10000 slowlog-max-len 128 latency-monitor-threshold 0 notify-keyspace-events "" hash-max-ziplist-entries 512 hash-max-ziplist-value 64 list-max-ziplist-entries 512 list-max-ziplist-value 64 set-max-intset-entries 512 zset-max-ziplist-entries 128 zset-max-ziplist-value 64 hll-sparse-max-bytes 3000 activerehashing yes client-output-buffer-limit normal 0 0 0 client-output-buffer-limit slave 256mb 64mb 60 client-output-buffer-limit pubsub 32mb 8mb 60 hz 10 aof-rewrite-incremental-fsync yes eof
（6）Redis2与Redis3上的redis-server配置文件
cat > /etc/redis/redis-6379.conf <<eof slaveof 192.168.1.241 6379 # maxmemory 268435456 maxmemory 256mb daemonize yes pidfile /data/redis-6379/redis-6379.pid port 6379 bind 0.0.0.0 tcp-backlog 511 timeout 0 tcp-keepalive 0 loglevel notice logfile /data/redis-6379/redis.log databases 16 save 900 1 save 300 10 save 60 10000 stop-writes-on-bgsave-error yes rdbcompression yes rdbchecksum yes dbfilename dumpredis-6379.rdb dir /data/redis-6379 slave-serve-stale-data yes slave-read-only yes repl-diskless-sync no repl-diskless-sync-delay 5 # repl-ping-slave-period 10 # repl-timeout 60 repl-disable-tcp-nodelay no # repl-backlog-size 1mb # repl-backlog-ttl 3600 slave-priority 100 # min-slaves-to-write 3 # min-slaves-max-lag 10 appendonly no appendfilename "appendonly.aof" appendfsync everysec no-appendfsync-on-rewrite no auto-aof-rewrite-percentage 100 auto-aof-rewrite-min-size 64mb aof-load-truncated yes lua-time-limit 5000 slowlog-log-slower-than 10000 slowlog-max-len 128 latency-monitor-threshold 0 notify-keyspace-events "" hash-max-ziplist-entries 512 hash-max-ziplist-value 64 list-max-ziplist-entries 512 list-max-ziplist-value 64 set-max-intset-entries 512 zset-max-ziplist-entries 128 zset-max-ziplist-value 64 hll-sparse-max-bytes 3000 activerehashing yes client-output-buffer-limit normal 0 0 0 client-output-buffer-limit slave 256mb 64mb 60 client-output-buffer-limit pubsub 32mb 8mb 60 hz 10 aof-rewrite-incremental-fsync yes eof
（7）Redis1上的keepalived配置文件(vim /etc/keepalived/keepalived.conf)
关于keepalived的配置文件
keepalived的配置文件默认是没有的，当然sample&example文件还是有的，通常在PREFIX/etc/sample目录下。
keepalived master和backup（backups）之间不同的是：
1.优先级的不同，master的优先级priority的数字要高一些
2.global_defs段的router_id都不一样，实际中可以用任意名字区分也可以用主机名区分
3.backup的配置文件中还有一个nopreempt字段，意思是设置为非抢占模式，作用是让master优先获取到VIP，并保证VIP是在原先的master上。
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 10
router_id keepalivedha_1
}
vrrp_script chk_http_port {
script "redis-cli info | grep role:master >/dev/null 2>&1"
interval 1
timeout 2
fall 2
rise 1
}
vrrp_sync_group VG_1 {
group {
VI_1
}
}
vrrp_instance VI_1 {
state BACKUP
interface eth1
#use_vmac keepalived
#vmac_xmit_base
mcast_src_ip 192.168.1.241
smtp_alert
virtual_router_id 20
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass password
}
virtual_ipaddress {
192.168.1.245
}
track_script {
chk_http_port
}
}（8）Redis2上的keepalived配置文件
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 10
router_id keepalivedha_2
}
vrrp_script chk_http_port {
script "redis-cli info | grep role:master >/dev/null 2>&1"
interval 1
timeout 2
fall 2
rise 1
}
vrrp_sync_group VG_1 {
group {
VI_1
}
}
vrrp_instance VI_1 {
state BACKUP
interface eth2
#use_vmac keepalived
#vmac_xmit_base
mcast_src_ip 192.168.1.242
smtp_alert
virtual_router_id 20
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass password
}
virtual_ipaddress {
192.168.1.245
}
track_script {
chk_http_port
}
nopreempt
}（9）Redis3上的keepalived配置文件
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 10
router_id keepalivedha_3
}
vrrp_script chk_http_port {
script "redis-cli info | grep role:master >/dev/null 2>&1"
interval 1
timeout 2
fall 2
rise 1
}
vrrp_sync_group VG_1 {
group {
VI_1
}
}
vrrp_instance VI_1 {
state BACKUP
interface eth1
#use_vmac keepalived
#vmac_xmit_base
mcast_src_ip 192.168.1.243
smtp_alert
virtual_router_id 20
priority 98
advert_int 1
authentication {
auth_type PASS
auth_pass password
}
virtual_ipaddress {
192.168.1.245
}
track_script {
chk_http_port
}
nopreempt
}（10）启动redis-server
redis-server /etc/redis/redis-6379.conf tail /data/redis-6379/redis.log
（11）启动redis-sentinel
redis-sentinel /etc/redis/redis-sentinel.conf tail /data/redis-6379/redis-sentinel.log
（12）启动keepalived
service keepalived start tail /var/log/messages
如果keepalived启动后日志如下图显示则表示启动成功。
先不模拟故障，先测试一下redis的set、get和复制情况
再测试一下模拟故障出现时redis的set、get和复制情况
停掉Redis1上的redis-server
Redis1上的VIP已经被移除
查看Redis2上的Redis状态和VIP状态
通过上图的黄色文字可以看出，VIP已经漂移到新的redis-server master了。
注意：VIP的漂移过程是需要时间的，时间大概需要10*4ms左右，如下图所示：
此时再次测试一下Redis的复制情况
由上图可见，Redis复制情况正常，上层应用依然可以使用Redis缓存服务。
如果一台主机宕机，则主机启动后，先启动redis-server、再启动redis-sentinel、最后自动keepalived。
如果多台主机宕机，则按照一台主机宕机的步骤做同样处理。
如果一台主机的中的某台服务停止，则直接启动该服务即可。
Redis Documention http://redis.io/documentation
Redis High Availability http://redis.io/topics/sentinel
Redis Replication http://redis.io/topics/replication
tag:Redis集群,Redis高可用,redis-sentinel,keepalived配置,Redis主从复制
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本文出自 “通信，我的最爱” 博客，请务必保留此出处http://dgd2010.blog.51cto.com/1539422/1742766
利用redis-sentinel+keepalived实现redis高可用
标签：keepalived配置 redis集群 redis主从复制 redis高可用 redis-sentinel
原文地址：http://dgd2010.blog.51cto.com/1539422/1742766
