Redis实现集群搭建+集群读写的示例_Redis

问题

容量不够，redis 如何进行扩容？并发写操作， redis 如何分摊？另外，主从模式，薪火相传模式，主机宕机，导致 ip 地址发生变化，应用程序中配置需要修改对应的主机地址、端口等信息。

之前通过代理主机来解决，但是 redis7.0 中提供了解决方案。就是 无中心化集群 配置：即每个节点都可以和其他节点进行联系。如 a、b、c 节点。想访问 b 节点，可以先访问 a 节点，a 节点会去联系 b 节点。无须代理服务器或者负载均衡去找对应的节点

什么是集群

redis 集群实现了对 redis 的水平扩容，即启动 n 个 redis 节点，将整个数据库分布存储在这 n 个节点中，每个节点存储总数据的 1/n。

redis 集群通过分区（partition）来提供一定程度的可用性（availability）：即使集群中有一部分节点失效或者无法进行通讯，集群也可以继续处理命令请求。

环境准备

将 rdb、aof 文件都删除掉
三台虚拟机，新建目录/myredis/cluster
制作 6 个实例，三主三从，三主机端口分别为 6381，6383，6385。三从机端口分别为6382，6384，6386（具体端口视情况）
每一个配置文件的基本信息修改（和 主从复制 - 哨兵模式 一样）
- 开启 daemonize yes
- 指定 6 个端口，不能重复
- 6 个 pid 文件名字配置，不能重复，尽量以加上端口进行识别
- 6 个 log 文件名字，不能重复，尽量以加上端口进行识别
- 6 个 dump.rdb 名字，不能重复，尽量以加上端口进行识别
- appendonly 关掉或者换名字
每一个配置文件的集群信息修改
- cluster-enabled yes：打开集群模式
- cluster-config-file nodes-6379.conf：设定节点配置文件名
- cluster-node-timeout 15000：设定节点失联时间，超过该时间（毫秒），集群自动进行主从切换

配置文件模板（替换端口号）：

[root@redis-cluster2 cluster]# cat rediscluster6383.conf 
bind 0.0.0.0
daemonize yes
protected-mode no
logfile "/myredis/cluster/cluster6383.log"
pidfile /myredis/cluster6383.pid
dir /myredis/cluster
dbfilename dump6383.rdb
appendonly yes
appendfilename "appendonly6383.aof"
requirepass 111111
masterauth 111111
port 6383

cluster-enabled yes
cluster-config-file nodes-6383.conf
cluster-node-timeout 5000

将以上配置文件分别写入到三台虚拟机中，每个虚拟机其两个redis服务，使用redis-server指定配置文件启动

[root@redis-cluster2 cluster]# redis-server /myredis/cluster/rediscluster6383.conf 
[root@redis-cluster2 cluster]# redis-server /myredis/cluster/rediscluster6384.conf 
[root@redis-cluster2 cluster]# ps -ef | grep redis
root        1950       1  0 15:38 ?        00:00:00 redis-server 0.0.0.0:6383 [cluster]
root        1956       1  0 15:38 ?        00:00:00 redis-server 0.0.0.0:6384 [cluster]
root        1962    1569  0 15:38 pts/0    00:00:00 grep --color=auto redis

通过命令redis-cli为集群构建主从关系

[root@k8s-master01 cluster]# redis-cli -a 111111 --cluster create --cluster-replicas 1 192.168.58.129:6381 192.168.58.129:6382 192.168.58.130:6383 192.168.58.130:6384 192.168.58.212:6385 192.168.58.212:6386
warning: using a password with '-a' or '-u' option on the command line interface may not be safe.
>>> performing hash slots allocation on 6 nodes...
master[0] -> slots 0 - 5460
master[1] -> slots 5461 - 10922
master[2] -> slots 10923 - 16383
adding replica 192.168.58.130:6384 to 192.168.58.129:6381
adding replica 192.168.58.212:6386 to 192.168.58.130:6383
adding replica 192.168.58.129:6382 to 192.168.58.212:6385
m: 772165af2d8a6b4600833ff36f33d1fe02acfa96 192.168.58.129:6381
   slots:[0-5460] (5461 slots) master
s: 5edb851c0aa5de08924f1d079c21b668e74e14ab 192.168.58.129:6382
   replicates c1e8aaf10e92cd3aebffe1247d8c99a9d857e916
m: e722f20399055c4543aa5a60697a1c6cebfe8e06 192.168.58.130:6383
   slots:[5461-10922] (5462 slots) master
s: afc75f35d9856b15040460f3373fd658907e1cc8 192.168.58.130:6384
   replicates 772165af2d8a6b4600833ff36f33d1fe02acfa96
m: c1e8aaf10e92cd3aebffe1247d8c99a9d857e916 192.168.58.212:6385
   slots:[10923-16383] (5461 slots) master
s: a256bdaeafd97ff59a4e59d994046ff102e7509b 192.168.58.212:6386
   replicates e722f20399055c4543aa5a60697a1c6cebfe8e06
can i set the above configuration? (type 'yes' to accept): yes
>>> nodes configuration updated
>>> assign a different config epoch to each node
>>> sending cluster meet messages to join the cluster
waiting for the cluster to join
.
>>> performing cluster check (using node 192.168.58.129:6381)
m: 772165af2d8a6b4600833ff36f33d1fe02acfa96 192.168.58.129:6381
   slots:[0-5460] (5461 slots) master
   1 additional replica(s)
s: afc75f35d9856b15040460f3373fd658907e1cc8 192.168.58.130:6384
   slots: (0 slots) slave
   replicates 772165af2d8a6b4600833ff36f33d1fe02acfa96
s: 5edb851c0aa5de08924f1d079c21b668e74e14ab 192.168.58.129:6382
   slots: (0 slots) slave
   replicates c1e8aaf10e92cd3aebffe1247d8c99a9d857e916
m: e722f20399055c4543aa5a60697a1c6cebfe8e06 192.168.58.130:6383
   slots:[5461-10922] (5462 slots) master
   1 additional replica(s)
s: a256bdaeafd97ff59a4e59d994046ff102e7509b 192.168.58.212:6386
   slots: (0 slots) slave
   replicates e722f20399055c4543aa5a60697a1c6cebfe8e06
m: c1e8aaf10e92cd3aebffe1247d8c99a9d857e916 192.168.58.212:6385
   slots:[10923-16383] (5461 slots) master
   1 additional replica(s)
[ok] all nodes agree about slots configuration.
>>> check for open slots...
>>> check slots coverage...
[ok] all 16384 slots covered.
[root@k8s-master01 cluster]# ll
total 52
drwxr-xr-x. 2 root root  4096 dec  1 15:30 appendonlydir
-rw-r--r--. 1 root root 10718 dec  1 15:50 cluster6381.log
-rw-r--r--. 1 root root 15205 dec  1 15:50 cluster6382.log
-rw-r--r--. 1 root root   171 dec  1 15:49 dump6382.rdb
-rw-r--r--. 1 root root   799 dec  1 15:49 nodes-6381.conf
-rw-r--r--. 1 root root   811 dec  1 15:49 nodes-6382.conf
-rw-r--r--. 1 root root   347 dec  1 15:32 rediscluster6381.conf
-rw-r--r--. 1 root root   346 dec  1 15:32 rediscluster6382.conf

以6381为切入点查看集群状态

[root@k8s-master01 cluster]# redis-cli -a 111111 -p 6381
warning: using a password with '-a' or '-u' option on the command line interface may not be safe.
127.0.0.1:6381> 
127.0.0.1:6381> info replication
# replication
role:master
connected_slaves:1
slave0:ip=192.168.58.130,port=6384,state=online,offset=224,lag=0
master_failover_state:no-failover
master_replid:6955624b397904832e2911972f1c9b871e8b86fc
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:224
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:224
127.0.0.1:6381>

集群指令

查看集群信息

127.0.0.1:6381> cluster nodes
afc75f35d9856b15040460f3373fd658907e1cc8 192.168.58.130:6384@16384 slave 772165af2d8a6b4600833ff36f33d1fe02acfa96 0 1733039642782 1 connected
5edb851c0aa5de08924f1d079c21b668e74e14ab 192.168.58.129:6382@16382 slave c1e8aaf10e92cd3aebffe1247d8c99a9d857e916 0 1733039641297 5 connected
e722f20399055c4543aa5a60697a1c6cebfe8e06 192.168.58.130:6383@16383 master - 0 1733039641617 3 connected 5461-10922
a256bdaeafd97ff59a4e59d994046ff102e7509b 192.168.58.212:6386@16386 slave e722f20399055c4543aa5a60697a1c6cebfe8e06 0 1733039641067 3 connected
c1e8aaf10e92cd3aebffe1247d8c99a9d857e916 192.168.58.212:6385@16385 master - 0 1733039640849 5 connected 10923-16383
772165af2d8a6b4600833ff36f33d1fe02acfa96 192.168.58.129:6381@16381 myself,master - 0 1733039639000 1 connected 0-5460

查看键的插槽值

cluster keyslot k1
192.168.58.129:6381> cluster keyslot k1
(integer) 12706
192.168.58.129:6381> cluster keyslot k2
(integer) 449

查看插槽值里有几个key

cluster countkeysinslot 4847             #只能看自己插槽的值

查询集群中的值

cluster getkeysinslot <slot> <count>     #返回 count 个 slot 槽中的键

查看单节点

127.0.0.1:6381> cluster info
cluster_state:ok
cluster_slots_assigned:16384
cluster_slots_ok:16384
cluster_slots_pfail:0
cluster_slots_fail:0
cluster_known_nodes:6
cluster_size:3
cluster_current_epoch:6
cluster_my_epoch:1
cluster_stats_messages_ping_sent:1226
cluster_stats_messages_pong_sent:1199
cluster_stats_messages_sent:2425
cluster_stats_messages_ping_received:1194
cluster_stats_messages_pong_received:1226
cluster_stats_messages_meet_received:5
cluster_stats_messages_received:2425
total_cluster_links_buffer_limit_exceeded:0

集群读写

在6381进行写操作时，set k1出现报错，显示到6385进行写，操作，set k2 却可以执行成功，这是为什么呢？

127.0.0.1:6381> set k1 v1
(error) moved 12706 192.168.58.212:6385
127.0.0.1:6381> set k2 v2
ok
127.0.0.1:6381> keys *
1) "k2"
127.0.0.1:6381>

是因为集群在创建时，分配了三个槽位，必须在各自的槽位进行写操作

如何解决？

防止路由失效，添加参数-c并新增两个key

127.0.0.1:6381> flushall
ok
127.0.0.1:6381> keys *
(empty array)
127.0.0.1:6381> quit
[root@k8s-master01 cluster]# redis-cli -a 111111 -p 6381 -c
warning: using a password with '-a' or '-u' option on the command line interface may not be safe.
127.0.0.1:6381> 
127.0.0.1:6381> 
127.0.0.1:6381> keys *
(empty array)
127.0.0.1:6381> set k1 v1 
-> redirected to slot [12706] located at 192.168.58.212:6385
ok
192.168.58.212:6385> 
192.168.58.212:6385> set k2 v2 
-> redirected to slot [449] located at 192.168.58.129:6381
ok

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