How to build a Redis cluster

Redis cluster is a distributed service cluster composed of multiple master-slave node groups. It has replication, high availability and sharding features. Redis cluster can complete node removal and failover functions without sentinel. Each node needs to be set to cluster mode. This cluster mode has no central node and can be expanded horizontally. According to official documents, it can be linearly expanded to tens of thousands of nodes (the official recommendation is no more than 1,000 nodes). The performance and high availability of the redis cluster are better than the previous version of sentinel mode, and the cluster configuration is very simple.

Build environment

System: centos7.4

Server Kingsoft Cloud

Install ruby ​​environment

[root@jsy-bj-test00 ~]# yum install -y ruby rubygems

Copy 6 copies of redis service

[work@jsy-bj-test00 ~]$ cp -rp redis redis1
[work@jsy-bj-test00 ~]$ cp -rp redis redis2
[work@jsy-bj-test00 ~]$ cp -rp redis redis3

Redis configuration file modification

#六个节点需做如下更改[work@jsy-bj-test00 ~]$ vim redis1/etc/redis.conf
[work@jsy-bj-test00 ~]$ sed -i 's/port 6379/port 6380/g' redis5/etc/redis.conf #修改端口 port 6380#打开注释，开启集群模式cluster-enabled yes#集群的配置文件cluster-config-file nodes-6380.conf
[work@jsy-bj-test00 ~]$ sed -i 's/cluster-config-file nodes-6379.conf/cluster-config-file nodes-6380.conf/g' redis5/etc/redis.conf#pidfile文件pidfile /var/run/redis_6380.pid
[work@jsy-bj-test00 ~]$ sed -i 's/pidfile \/var\/run\/redis_6380.pid/pidfile \/var\/run\/redis_6380.pid/g' redis5/etc/redis.conf#日志文件  logfile "/home/work/logs/redis/6380.log"[work@jsy-bj-test00 ~]$ sed -i 's/logfile "\/home\/work\/logs\/redis\/6379.log"/logfile "\/home\/work\/logs\/redis\/6380.log"/g' redis5/etc/redis.conf#rdb持久化文件  dbfilename dump6380.rdb
[work@jsy-bj-test00 ~]$ sed -i 's/dbfilename dump6379.rdb/dbfilename dump6380.rdb/g' redis5/etc/redis.conf#请求超时，单位毫秒cluster-node-timeout 5000#开启aof持久化方式appendonly yes#配置持久化文件appendfilename "appendonly6379.aof"[work@jsy-bj-test00 ~]$ sed -i 's/appendfilename "appendonly6379.aof"/appendfilename "appendonly6383.aof"/g' redis5/etc/redis.conf

Write cluster start script and stop script

Start script start_all.sh

/home/work/redis/bin/redis-server /home/work/redis/etc/redis.conf &
/home/work/redis/bin/redis-server /home/work/redis/etc/redis6380.conf &
/home/work/redis/bin/redis-server /home/work/redis/etc/redis6381.conf &
/home/work/redis/bin/redis-server /home/work/redis/etc/redis6382.conf &
/home/work/redis/bin/redis-server /home/work/redis/etc/redis6383.conf &
/home/work/redis/bin/redis-server /home/work/redis/etc/redis6384.conf &

Close the script stop_all.sh

/home/work/redis/bin/redis-cli -p 6379 -a test shutdown
/home/work/redis/bin/redis-cli -p 6380 -a test shutdown
/home/work/redis/bin/redis-cli -p 6381 -a test shutdown
/home/work/redis/bin/redis-cli -p 6382 -a test shutdown
/home/work/redis/bin/redis-cli -p 6383 -a test shutdown
/home/work/redis/bin/redis-cli -p 6384 -a test shutdown

Execute the create cluster command

The following error is reported

[work@jsy-bj-test00 src]$ ./redis-trib.rb create --replicas 1 127.0.0.1:6379 127.0.0.1:6380 127.0.0.1:6381 127.0.0.1:6382 127.0.0.1:6383 127.0.0.1:6384
/usr/share/rubygems/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- redis (LoadError)
from /usr/share/rubygems/rubygems/core_ext/kernel_require.rb:55:in `require'from ./redis-trib.rb:25:in `

‘

Cause: The error when installing the redis interface reported that the ruby ​​version is too low

[root@jsy-bj-test00 ~]# gem install redisFetching: redis-4.1.3.gem (100%)
ERROR: Error installing redis:
redis requires Ruby version >= 2.3.0.

The solution is to download the latest stable version source code from the official website http://www.ruby-lang.org/en/downloads/ for compilation and installation

[work@jsy-bj-test00 soft]$ tar zxvf ruby-2.7.0.tar.gz
[work@jsy-bj-test00 soft]$ cd ruby-2.7.0
[work@jsy-bj-test00 ruby-2.7.0]$ ./configure --prefix=/home/work/ruby && make && make install

Install redis interface

[work@jsy-bj-test00 bin]$ gem install redis

Execute the create cluster command again

[work@jsy-bj-test00 src]$ ./redis-trib.rb create --replicas 1 127.0.0.1:6379 127.0.0.1:6380 127.0.0.1:6381 127.0.0.1:6382 127.0.0.1:6383 127.0.0.1:6384
>>> Creating cluster
>>> Performing hash slots allocation on 6 nodes...
......
>>> 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 127.0.0.1:6379)
......
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.

Creation is successful, check cluster status

[work@jsy-bj-test00 ~]$ ./redis/bin/redis-cli -h 127.0.0.1 -p 6379 -c
127.0.0.1:6379> 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_sent:627
cluster_stats_messages_received:627

View cluster node information

127.0.0.1:6379> cluster nodes
565246bf31d8e05e464db7455521b1a9f165a9cd 127.0.0.1:6380 master - 0 1578447776230 2 connected 5461-10922
1b99b2a1e4b530501476ab48422c75f30423fd19 127.0.0.1:6383 slave 565246bf31d8e05e464db7455521b1a9f165a9cd 0 1578447778233 5 connected
735ad5778458059316794b9378d4b81aaff20322 127.0.0.1:6379 myself,master - 0 0 1 connected 0-5460
757c2c11ecebfc607aa10a6877e348d0e2da484f 127.0.0.1:6381 master - 0 1578447777732 3 connected 10923-16383
f22efc2bcfcd11cee6487ebc9c75de3b59f5e1d0 127.0.0.1:6382 slave 735ad5778458059316794b9378d4b81aaff20322 0 1578447776230 4 connected
b8bba94b9647caa8600363144fd7108082e45f56 127.0.0.1:6384 slave 757c2c11ecebfc607aa10a6877e348d0e2da484f 0 1578447777232 6 connected#这是很重要的命令，我们需要关心的信息有：#第一个参数：节点ID#第二个参数：IP:PORT@TCP 这里一个坑，jedis-2.9.0之前的版本解析@出错#第三个参数：标志（Master，Slave，Myself，Fail...）#第四个参数：如果是从机则是主机的节点ID#最后两个参数：连接的状态和槽的位置。

Cluster management related commands

#集群增加节点，先复制两个配置文件，并修改配置文件内容[work@jsy-bj-test00 etc]$ cp -p redis.conf redis6385.conf
[work@jsy-bj-test00 etc]$ cp -p redis.conf redis6386.conf
[work@jsy-bj-test00 etc]$ sed -i 's/6379/6385/g' redis6385.conf
[work@jsy-bj-test00 etc]$ sed -i 's/6379/6386/g' redis6386.conf

Start 6385 nodes

[work@jsy-bj-test00 bin]$ ./redis-server /home/work/redis/etc/redis6385.conf &

Softly connect the cluster management tool to the bin of redis

[work@jsy-bj-test00 bin]$ ln -s /home/work/soft/redis-3.2.11/src/redis-trib.rb /home/work/redis/bin/redis-trib.rb

Add the new node to the cluster master

[work@jsy-bj-test00 bin]$ ./redis-trib.rb add-node 127.0.0.1:6385 127.0.0.1:6379
>>> Adding node 127.0.0.1:6385 to cluster 127.0.0.1:6379
>>> Performing Cluster Check (using node 127.0.0.1:6379)
......
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
>>> Send CLUSTER MEET to node 127.0.0.1:6385 to make it join the cluster.
[OK] New node added correctly.

Check the cluster status, no slots are allocated

[work@jsy-bj-test00 bin]$ ./redis-cli -h 127.0.0.1 -p 6379 -c cluster nodes
d00d05f601df0b69df0c2cc532b636d2c83347be 127.0.0.1:6385 master - 0 1578450280191 0 connected

Assign slots to 6385 nodes

[work@jsy-bj-test00 bin]$ ./redis-trib.rb reshard 127.0.0.1:6379
>>> Performing Cluster Check (using node 127.0.0.1:6379)
......
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
How many slots do you want to move (from 1 to 16384)? 500
What is the receiving node ID? d00d05f601df0b69df0c2cc532b636d2c83347be
Please enter all the source node IDs.
Type 'all' to use all the nodes as source nodes for the hash slots.
Type 'done' once you entered all the source nodes IDs.
Source node #1:allDo you want to proceed with the proposed reshard plan (yes/no)? yes#第一个参数：需要移动槽的个数，#第二个参数：接受槽的节点ID，#第三个参数：输入"all"表示从所有原节点中获取槽，#第四个参数：输入"yes"开始移动槽到目标结点id#查看6385节点信息，已经分配槽位[work@jsy-bj-test00 bin]$ ./redis-cli -h 127.0.0.1 -p 6379 -c cluster nodes
d00d05f601df0b69df0c2cc532b636d2c83347be 127.0.0.1:6385 master - 0 1578452422167 7 connected 0-165 5461-5627 10923-11088

Add slave nodes, start 6386 nodes and join the cluster

[work@jsy-bj-test00 bin]$ ./redis-server /home/work/redis/etc/redis6386.conf &
[work@jsy-bj-test00 bin]$ ./redis-trib.rb add-node --slave --master-id d00d05f601df0b69df0c2cc532b636d2c83347be 127.0.0.1:6386 127.0.0.1:6385
>>> Adding node 127.0.0.1:6386 to cluster 127.0.0.1:6385
>>> Performing Cluster Check (using node 127.0.0.1:6385)
......
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
>>> Send CLUSTER MEET to node 127.0.0.1:6386 to make it join the cluster.
Waiting for the cluster to join.
>>> Configure node as replica of 127.0.0.1:6385.
[OK] New node added correctly.

View 6386 Node status

[work@jsy-bj-test00 bin]$ ./redis-cli -h 127.0.0.1 -p 6379 -c cluster nodes
6845878cbef3fe25f19a70a8db3eb29abb1b9ea6 127.0.0.1:6386 slave d00d05f601df0b69df0c2cc532b636d2c83347be 0 1578452805439 7 connected

Delete node

[work@jsy-bj-test00 bin]$ ./redis-trib.rb del-node 127.0.0.1:6383 1b99b2a1e4b530501476ab48422c75f30423fd19
>>> Removing node 1b99b2a1e4b530501476ab48422c75f30423fd19 from cluster 127.0.0.1:6383
>>> Sending CLUSTER FORGET messages to the cluster...
>>> SHUTDOWN the node.

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