简介
Redis Cluster是Redis官方的一个高可用分布式解决方案，其优点是高可用，缺点是不能保证数据强一致。在这里使用docker容器来搭建一套6节点(3主，3从)Redis-Cluster集群环境。
环境准备
操作系统版本：CentOS Linux release 7.6.1810 (Core)
docker版本：19.03.13
服务器IP地址：192.168.112.136
redis版本：5.0.9
redis实例端口：8001--8006
docker安装
首先需要在CentOS系统上安装好docker软件，目前docker软件分为社区版ce和企业版ee，企业版是需要收费的，所以在这里使用社区版，要安装docker软件，CentOS系统的内核版本高于 3.10。
下面是docker安装步骤
yum install -y yum-utils device-mapper-persistent-data lvm2yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repoyum install docker-ce启动并加入开机启动systemctl start dockersystemctl enable docker由于docker默认是从国外拉取镜像，速度会比较慢，所以需要配置docker从国内的镜像网站拉取镜像，其配置步骤如下所示
将国内镜像网站添加到daemon.json配置文件
>/etc/docker/daemon.json{ "registry-mirrors": [ "https://registry.docker-cn.com", "https://docker.mirrors.ustc.edu.cn", "https://reg-mirror.qiniu.com", "https://mirror.ccs.tencentyun.com" ]}添加完成之后，需要重启docker服务器，使配置生效
systemctl daemon-reloadsystemctl restart dockerdocker服务器重启之后，使用docker info命令，检查配置是否生效
redis镜像拉取
在docker-hub官网，有很多版本的redis镜像可供选择，在这里，选择redis:5.0.9-buster进行拉取
[root@mysql ~]# docker pull redis:5.0.9-buster[root@mysql ~]# docker imagesREPOSITORY TAG IMAGE ID CREATED SIZEredis 5.0.9-buster c440306287f4 7 days ago 98.3MB创建redis目录和配置文件
由于这里需要配置6个redis实例的配置文件，所以在这里，可以先创建一个模板配置文件，之后使用代码批量替换的方式来创建每个redis的配置文件。
创建模板文件
创建目录
创建目录mkdir -p /data/docker_redis/编写redis_cluster.conf.template文件vi redis_cluster.conf.templateport ${PORT}requirepass 1234masterauth 1234protected-mode nodaemonize noappendonly yescluster-enabled yescluster-config-file nodes.confcluster-node-timeout 5000cluster-announce-ip 192.168.112.136cluster-announce-port ${PORT}cluster-announce-bus-port 1${PORT}在这里需要讲解2个参数
cluster-announce-port：此端口为redis提供服务端口，用于应用客户端连接
cluster-announce-bus-port：此端口用于redis集群进行故障检测、配置更新、故障转移授权和内部通讯使用，不用于应用客户端连接使用。
创建6个redis实例的数据目录，配置文件目录和配置文件
for port in `seq 8001 8006`; do \ mkdir -p /data/redis_data/${port}/conf \ && PORT=${port} envsubst < /data/docker_redis/redis_cluster.conf.template > /data/redis_data/${port}/conf/redis.conf \ && mkdir -p /data/redis_data/${port}/data;\done使用tree命令检查创建的目录和文件
[root@mysql data]$ tree redis_data/redis_data/|-- 8001| |-- conf| | `-- redis.conf| `-- data|-- 8002| |-- conf| | `-- redis.conf| `-- data|-- 8003| |-- conf| | `-- redis.conf| `-- data|-- 8004| |-- conf| | `-- redis.conf| `-- data|-- 8005| |-- conf| | `-- redis.conf| `-- data`-- 8006 |-- conf | `-- redis.conf `-- data18 directories, 6 files批量创建容器
在这里使用for循环批量创建redis容器，代码如下所示
for port in $(seq 8001 8006); do \ docker run -d -it -p ${port}:${port} -p 1${port}:1${port} --restart always --name redis-${port} \ -v /data/redis_data/${port}/conf/redis.conf:/usr/local/etc/redis/redis.conf \ -v /data/redis_data/${port}/data:/data \ redis:5.0.9-buster redis-server /usr/local/etc/redis/redis.conf; \done在这里使用-v参数，让容器的redis配置参数和数据全部使用宿主机的文件目录。这样做的好处是，保证redis的数据不丢失。
查看刚刚创建的redis容器
[root@mysql data]# docker psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMESf4c971ce2d84 redis:5.0.9-buster "docker-entrypoint.s鈥 6 seconds ago Up 5 seconds 0.0.0.0:8006->8006/tcp, 6379/tcp, 0.0.0.0:18006->18006/tcp redis-80061b5a8b0a1c93 redis:5.0.9-buster "docker-entrypoint.s鈥 7 seconds ago Up 6 seconds 0.0.0.0:8005->8005/tcp, 6379/tcp, 0.0.0.0:18005->18005/tcp redis-800535d8fe01fc71 redis:5.0.9-buster "docker-entrypoint.s鈥 7 seconds ago Up 6 seconds 0.0.0.0:8004->8004/tcp, 6379/tcp, 0.0.0.0:18004->18004/tcp redis-8004408e5302378a redis:5.0.9-buster "docker-entrypoint.s鈥 8 seconds ago Up 7 seconds 0.0.0.0:8003->8003/tcp, 6379/tcp, 0.0.0.0:18003->18003/tcp redis-8003c1c23c543233 redis:5.0.9-buster "docker-entrypoint.s鈥 8 seconds ago Up 7 seconds 0.0.0.0:8002->8002/tcp, 6379/tcp, 0.0.0.0:18002->18002/tcp redis-8002c752fab6c6b8 redis:5.0.9-buster "docker-entrypoint.s鈥 9 seconds ago Up 8 seconds 0.0.0.0:8001->8001/tcp, 6379/tcp, 0.0.0.0:18001->18001/tcp redis-8001创建redis-cluster集群
6个redis容器创建好之后，选择其中的一个容器进入，进行redis-cluster集群创建
[root@mysql bin]# docker-enter f4c971ce2d84root@f4c971ce2d84:~# redis-cli -a 1234 --cluster create 192.168.112.136:8001 192.168.112.136:8002 192.168.112.136:8003 192.168.112.136:8004 192.168.112.136:8005 192.168.112.136:8006 --cluster-replicas 1Warning: 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 - 5460Master[1] -> Slots 5461 - 10922Master[2] -> Slots 10923 - 16383Adding replica 192.168.112.136:8005 to 192.168.112.136:8001Adding replica 192.168.112.136:8006 to 192.168.112.136:8002Adding replica 192.168.112.136:8004 to 192.168.112.136:8003>>> Trying to optimize slaves allocation for anti-affinity[WARNING] Some slaves are in the same host as their masterM: c9e549f4d04d4466d2550d1e027412304099b1f2 192.168.112.136:8001 slots:[0-5460] (5461 slots) masterM: 0956927ee74737d5ff91a1885e77f94d531dab76 192.168.112.136:8002 slots:[5461-10922] (5462 slots) masterM: d6321788b2717b4142390c158ba70ca758f70964 192.168.112.136:8003 slots:[10923-16383] (5461 slots) masterS: 96d2cb55f163ecc13a714ba01d90348c1c3ad02f 192.168.112.136:8004 replicates c9e549f4d04d4466d2550d1e027412304099b1f2S: 8a771c26a95e82d9a6818e372d7c0226937670ac 192.168.112.136:8005 replicates 0956927ee74737d5ff91a1885e77f94d531dab76S: aa7c2f6173904973f041b35efc5200359188eb0f 192.168.112.136:8006 replicates d6321788b2717b4142390c158ba70ca758f70964Can 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 clusterWaiting for the cluster to join.>>> Performing Cluster Check (using node 192.168.112.136:8001)M: c9e549f4d04d4466d2550d1e027412304099b1f2 192.168.112.136:8001 slots:[0-5460] (5461 slots) master 1 additional replica(s)M: 0956927ee74737d5ff91a1885e77f94d531dab76 192.168.112.136:8002 slots:[5461-10922] (5462 slots) master 1 additional replica(s)S: 96d2cb55f163ecc13a714ba01d90348c1c3ad02f 192.168.112.136:8004 slots: (0 slots) slave replicates c9e549f4d04d4466d2550d1e027412304099b1f2S: aa7c2f6173904973f041b35efc5200359188eb0f 192.168.112.136:8006 slots: (0 slots) slave replicates d6321788b2717b4142390c158ba70ca758f70964S: 8a771c26a95e82d9a6818e372d7c0226937670ac 192.168.112.136:8005 slots: (0 slots) slave replicates 0956927ee74737d5ff91a1885e77f94d531dab76M: d6321788b2717b4142390c158ba70ca758f70964 192.168.112.136:8003 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.上述命令执行之后，redis-cluster集群就搭建好了，下面是整个redis-cluster集群的架构图
redis-cluster集群状态检查
检查redis-cluster集群状态
root@f4c971ce2d84:~# redis-cli -a 1234 --cluster check 192.168.112.136:8001Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.192.168.112.136:8001 (c9e549f4...) -> 0 keys | 5461 slots | 1 slaves.192.168.112.136:8002 (0956927e...) -> 0 keys | 5462 slots | 1 slaves.192.168.112.136:8003 (d6321788...) -> 0 keys | 5461 slots | 1 slaves.[OK] 0 keys in 3 masters.0.00 keys per slot on average.>>> Performing Cluster Check (using node 192.168.112.136:8001)M: c9e549f4d04d4466d2550d1e027412304099b1f2 192.168.112.136:8001 slots:[0-5460] (5461 slots) master 1 additional replica(s)M: 0956927ee74737d5ff91a1885e77f94d531dab76 192.168.112.136:8002 slots:[5461-10922] (5462 slots) master 1 additional replica(s)S: 96d2cb55f163ecc13a714ba01d90348c1c3ad02f 192.168.112.136:8004 slots: (0 slots) slave replicates c9e549f4d04d4466d2550d1e027412304099b1f2S: aa7c2f6173904973f041b35efc5200359188eb0f 192.168.112.136:8006 slots: (0 slots) slave replicates d6321788b2717b4142390c158ba70ca758f70964S: 8a771c26a95e82d9a6818e372d7c0226937670ac 192.168.112.136:8005 slots: (0 slots) slave replicates 0956927ee74737d5ff91a1885e77f94d531dab76M: d6321788b2717b4142390c158ba70ca758f70964 192.168.112.136:8003 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.检查redis集群节点信息
root@f4c971ce2d84:~# redis-cli -c -a 1234 -h 192.168.112.136 -p 8001192.168.112.136:8001> cluster nodes0956927ee74737d5ff91a1885e77f94d531dab76 192.168.112.136:8002@18002 master - 0 1603265855374 2 connected 5461-1092296d2cb55f163ecc13a714ba01d90348c1c3ad02f 192.168.112.136:8004@18004 slave c9e549f4d04d4466d2550d1e027412304099b1f2 0 1603265856080 4 connectedaa7c2f6173904973f041b35efc5200359188eb0f 192.168.112.136:8006@18006 slave d6321788b2717b4142390c158ba70ca758f70964 0 1603265855575 6 connected8a771c26a95e82d9a6818e372d7c0226937670ac 192.168.112.136:8005@18005 slave 0956927ee74737d5ff91a1885e77f94d531dab76 0 1603265855575 5 connectedd6321788b2717b4142390c158ba70ca758f70964 192.168.112.136:8003@18003 master - 0 1603265856382 3 connected 10923-16383c9e549f4d04d4466d2550d1e027412304099b1f2 192.168.112.136:8001@18001 myself,master - 0 1603265855000 1 connected 0-5460在这里可以很清晰明了的看到有3个master节点和3个slave节点的IP地址和端口信息。
redis-cluster连接测试
redis-cluster搭建好之后，随意连接一个redis节点，无论是主节点还是从节点都可以，在这里选择连接一个从节点。
192.168.112.136:8001> cluster nodes0956927ee74737d5ff91a1885e77f94d531dab76 192.168.112.136:8002@18002 master - 0 1603265855374 2 connected 5461-1092296d2cb55f163ecc13a714ba01d90348c1c3ad02f 192.168.112.136:8004@18004 slave c9e549f4d04d4466d2550d1e027412304099b1f2 0 1603265856080 4 connectedaa7c2f6173904973f041b35efc5200359188eb0f 192.168.112.136:8006@18006 slave d6321788b2717b4142390c158ba70ca758f70964 0 1603265855575 6 connected8a771c26a95e82d9a6818e372d7c0226937670ac 192.168.112.136:8005@18005 slave 0956927ee74737d5ff91a1885e77f94d531dab76 0 1603265855575 5 connectedd6321788b2717b4142390c158ba70ca758f70964 192.168.112.136:8003@18003 master - 0 1603265856382 3 connected 10923-16383c9e549f4d04d4466d2550d1e027412304099b1f2 192.168.112.136:8001@18001 myself,master - 0 1603265855000 1 connected 0-5460root@f4c971ce2d84:~# redis-cli -c -a 1234 -h 192.168.112.136 -p 8004Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.192.168.112.136:8004> 192.168.112.136:8004> set 5 test5-> Redirected to slot [9974] located at 192.168.112.136:8002192.168.112.136:8002>仔细看一下，当在slave节点写入数据时，redis-cluster将你的写请求重定向到另一个master节点了，至于原因，在这里就不说了，下次在讲解redis-cluster集群原理篇再细讲。
测试查询
root@f4c971ce2d84:~# redis-cli -c -a 1234 -h 192.168.112.136 -p 8006Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.192.168.112.136:8006> 192.168.112.136:8006> get 5-> Redirected to slot [9974] located at 192.168.112.136:8002"test5"192.168.112.136:8002>在这里查询也被路由重定向了。