文章来源:https://www.cnblogs.com/hello-tl/p/9244550.html
原理 1.集群管理器将16384个哈希槽点平均分配到三台master上，只有master会有槽点。具体算法是对key进行哈希求余，得到的余数落在那个节点的哈希槽点范围内，就分到那台master上 2.只有master才有槽点 3.一个从节点只对应一个master节点，即只会复制那个master节点的数据。如果master节点坏了，其中一个slave节点会升级为master。如果master和从节点都坏了，那么master对应的数据就丢了。 4.只有主节点可以被写入，从节点只是同步。 5.AOF同步保存，RDB有保存的规则。
0.准备六个虚拟机 / 六台服务器
集群中有三个主节点，三个从节点，一共六个结点。因此要构建六个redis的docker容器。
在宿主机中将这六个独立的redis结点关联成一个redis集群。需要用到官方提供的ruby脚本。
安装好之后必须步骤
1.开启22 / 6379 / 16379 端口 注意：每一台虚拟机上都是如此执行
# systemctl start firewalld # firewall-cmd --zone=public --add-port=22/tcp --permanent # firewall-cmd --zone=public --add-port=6379/tcp --permanent # firewall-cmd --zone=public --add-port=16379/tcp --permanent # systemctl restart firewalld.service # yum install net-tools
2.更新 yum 原 # yum update (属实个人习惯 跟redis集群搭建并没任何软用)
3.安装 wget # yum install wget (属实个人习惯 跟redis集群搭建并没任何软用)
4.安装 vim # yum install vim (属实个人习惯 跟redis集群搭建并没任何软用)
5.ContOS 7.4 64 (mysql 优化工具 pt-query-digest 学习) root 123456：mysql 123456 跟咱们没关系
虚拟机明明上的ip地址已经标明
2.我用的linux远程工具是xshell 4 链接这六台虚拟机
3.安装docker（来自小田吃饺子-博客园） docker 安装 ：https://www.cnblogs.com/hello-tl/p/8901132.html
安装完并且启动docker
5.拉取redis4.0镜像并且启动
注意：每一个虚拟机上都是如此配置
docker安装redis详情步骤 （来自小田吃饺子-博客园） docker 安装redis : https://www.cnblogs.com/hello-tl/p/9239474.html
1.添加镜像 # docker pull redis:4.0 2.创建conf文件目录 # mkdir /data # mkdir /data/redis # mkdir /data/redis/conf4.0 3.创建redis.conf并且写入内容 # vim /data/redis/conf4.0/redis.conf 内容如下 # 持久化 appendonly yes # 端口 port 6379 # 密码 # requirepass password # masterauth password # 集群配置 cluster-enabled yes cluster-config-file nodes.conf cluster-node-timeout 5000 cluster-announce-ip xxx.xxx.x.xxx [自己电脑的ip] cluster-announce-port 6379 cluster-announce-bus-port 16379 4.创建自定义network # docker network create redis-net 5.执行命令启动 # docker run -d -ti -p 6379:6379 -p 16379:16379 -v /data/redis/conf4.0/redis.conf:/usr/local/etc/redis/redis.conf -v /data/redis/data:/data --restart always --name redis4.0 --net redis-net --sysctl net.core.somaxconn=1024 redis redis-server /usr/local/etc/redis/redis.conf
6.拉取ruby
# docker pull ruby:2.4
7.通过启动ruby来实现集群
注：随意一台服务器上运行即可
echo yes | docker run -i --rm --net=host ruby sh -c ' gem install redis && wget http://download.redis.io/redis-stable/src/redis-trib.rb && ruby redis-trib.rb create --replicas 1 192.168.1.152:6379 192.168.1.177:6379 192.168.1.187:6379 192.168.1.197:6379 192.168.1.105:6379 192.168.1.138:6379 '
注：进入集群
# docker run -it redis:4.0 redis-cli -c -h 172.17.0.1 -p 6379
8.以上命令显示 （表示成功）
Successfully installed redis-4.0.1 1 gem installed --2018-07-04 04:50:10-- http://download.redis.io/redis-stable/src/redis-trib.rb Resolving download.redis.io (download.redis.io)... 109.74.203.151 Connecting to download.redis.io (download.redis.io)|109.74.203.151|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 65991 (64K) [text/plain] Saving to: 'redis-trib.rb' 0K .......... .......... .......... .......... .......... 77% 107K 0s 50K .......... .... 100% 20.3M=0.5s 2018-07-04 04:50:11 (138 KB/s) - 'redis-trib.rb' saved [65991/65991] >>> Creating cluster >>> Performing hash slots allocation on 6 nodes... Using 3 masters: 192.168.1.152:6379 192.168.1.177:6379 192.168.1.187:6379 Adding replica 192.168.1.105:6379 to 192.168.1.152:6379 Adding replica 192.168.1.138:6379 to 192.168.1.177:6379 Adding replica 192.168.1.197:6379 to 192.168.1.187:6379 M: ef114f1afe3b19247bd2855d6c8b06558061df28 192.168.1.152:6379 slots:0-5460 (5461 slots) master M: 73e5be149d2ae5c73025da0cc3f5badc21e57c58 192.168.1.177:6379 slots:5461-10922 (5462 slots) master M: 99d6ecfa496726f50d5e24cebaa94648cde54b0a 192.168.1.187:6379 slots:10923-16383 (5461 slots) master S: 52c058d234b23db447fc9d5761d32af1cb60d911 192.168.1.197:6379 replicates 99d6ecfa496726f50d5e24cebaa94648cde54b0a S: e7af3586b42dbfe3bf312bd6b46b99ded953e5a1 192.168.1.105:6379 replicates ef114f1afe3b19247bd2855d6c8b06558061df28 S: a6f9990f84f5cef22d2293c320720f7b0d818dea 192.168.1.138:6379 replicates 73e5be149d2ae5c73025da0cc3f5badc21e57c58 Can I set the above configuration? (type 'yes' to accept): >>> 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 192.168.1.151:6379) M: ef114f1afe3b19247bd2855d6c8b06558061df28 192.168.1.152:6379 slots:0-5460 (5461 slots) master 1 additional replica(s) M: 73e5be149d2ae5c73025da0cc3f5badc21e57c58 192.168.1.177:6379 slots:5461-10922 (5462 slots) master 1 additional replica(s) S: a6f9990f84f5cef22d2293c320720f7b0d818dea 192.168.1.138:6379 slots: (0 slots) slave replicates 73e5be149d2ae5c73025da0cc3f5badc21e57c58 S: 52c058d234b23db447fc9d5761d32af1cb60d911 192.168.1.197:6379 slots: (0 slots) slave replicates 99d6ecfa496726f50d5e24cebaa94648cde54b0a S: e7af3586b42dbfe3bf312bd6b46b99ded953e5a1 192.168.1.105:6379 slots: (0 slots) slave replicates ef114f1afe3b19247bd2855d6c8b06558061df28 M: 99d6ecfa496726f50d5e24cebaa94648cde54b0a 192.168.1.187:6379 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.