如何搭建Redis集群与Jedis连接集群

1.redis-cluster架构图

架构细节:
(1)所有的redis节点彼此互联(PING-PONG机制),内部使用二进制协议优化传输速度和带宽.
(2)节点的fail是通过集群中超过半数的节点检测失效时才生效.
(3)客户端与redis节点直连,不需要中间proxy层.客户端不需要连接集群所有节点,连接集群中任何一个可用节点即可
(4)redis-cluster把所有的物理节点映射到[0-16383]slot上,cluster 负责维护node<->slot<->value

Redis 集群中内置了 16384 个哈希槽，当需要在 Redis 集群中放置一个 key-value 时，redis 先对 key 使用 crc16 算法算出一个结果，然后把结果对 16384 求余数，这样每个 key 都会对应一个编号在 0-16383 之间的哈希槽，redis 会根据节点数量大致均等的将哈希槽映射到不同的节点

示例如下：

2.redis-cluster投票:容错

(1)集群中所有master参与投票,如果半数以上master节点与其中一个master节点通信超过(cluster-node-timeout),认为该master节点挂掉.
(2):什么时候整个集群不可用(cluster_state:fail)
如果集群任意master挂掉,且当前master没有slave，则集群进入fail状态。也可以理解成集群的[0-16383]slot映射不完全时进入fail状态。如果集群超过半数以上master挂掉，无论是否有slave，集群进入fail状态。

3.搭建Ruby环境

redis集群管理工具redis-trib.rb依赖ruby环境，首先需要安装ruby环境。1）安装ruby    [root@localhost bin]#yum install ruby    [root@localhost bin]#yum install rubygems2）使用sftp工具上传redis-4.0.0.gem至/java下3）安装ruby和redis的接口程序    [root@localhost java]#gem install redis-4.0.0.gem4）将Redis集群搭建脚本文件复制到/opt/java/redis-cluster目录下    [root@localhost /]# cd /java/redis-4.0.0/src/    [root@localhost src]# ll *.rb    -rwxrwxr-x. 1 root root 48141 4月   1 2015 redis-trib.rb    [root@localhost src]# cp redis-trib.rb /opt/java/redis-cluster/ -r

4.集群的搭建过程

搭建集群最少也得需要3台主机，如果每台主机再配置一台从机的话，则最少需要6台机器。1）创建6个redis实例，需要端口号7001~7006，复制出一个7001机器[root@localhost redis]# cp bin ../redis-cluster/7001 -r2）如果存在持久化文件，则删除[root@localhost 7001]# rm -rf appendonly.aof  dump.rdb3）设置集群参数和修改端口

4）复制出7002-7006机器，然后修改7002-7006机器的端口[root@localhost redis-cluster]# cp 7001/ 7002 -r[root@localhost redis-cluster]# cp 7001/ 7003 -r[root@localhost redis-cluster]# cp 7001/ 7004 -r[root@localhost redis-cluster]# cp 7001/ 7005 -r[root@localhost redis-cluster]# cp 7001/ 7006 -r5）启动7001-7006这六台机器[root@localhost redis-cluster]# vi start.shcd 7001./redis-server redis.confcd ..cd 7002./redis-server redis.confcd ..cd 7003./redis-server redis.confcd ..cd 7004./redis-server redis.confcd ..cd 7005./redis-server redis.confcd ..cd 7006./redis-server redis.confcd ..[root@localhost redis-cluster]# chmod 777 start.sh [root@localhost redis-cluster]# ./start.sh [root@localhost redis-cluster]# ps -ef|grep redisroot       3750   3677  0 20:52 pts/2    00:00:00 cp -i redis-trib.rb /opt/java/redis-clusterroot       3779   3677  0 20:54 pts/2    00:00:00 cp -i redis-trib.rb /opt/java/redis-cluster -rroot       3791      1  1 20:55 ?        00:00:00 ./redis-server *:7001 [cluster]root       3795      1  0 20:55 ?        00:00:00 ./redis-server *:7002 [cluster]root       3799      1  0 20:55 ?        00:00:00 ./redis-server *:7003 [cluster]root       3803      1  0 20:55 ?        00:00:00 ./redis-server *:7004 [cluster]root       3807      1  1 20:55 ?        00:00:00 ./redis-server *:7005 [cluster]root       3811      1  0 20:55 ?        00:00:00 ./redis-server *:7006 [cluster]root       3815   3444  0 20:55 pts/1    00:00:00 grep --color=auto redis6）创建集群[root@localhost redis-cluster]# vi startCluster.sh ./redis-trib.rb create --replicas l 10.39.12.237:7001 10.39.12.237:7002 10.39.12.237:7003 10.39.12.237:7004 10.39.12.237:7005 10.39.12.237:7006[root@localhost redis-cluster]# chmod 777 startCluster.sh [root@localhost redis-cluster]# ./startCluster.sh >>> Creating clusterConnecting to node 10.39.12.237:7001: OK>>> Performing hash slots allocation on 6 nodes...Using 6 masters:10.39.12.237:700110.39.12.237:700210.39.12.237:700310.39.12.237:700410.39.12.237:700510.39.12.237:7006............................Can I set the above configuration? (type 'yes' to accept): yes..........................[OK] All nodes agree about slots configuration.>>> Check for open slots...>>> Check slots coverage...[OK] All 16384 slots covered.

5.连接集群

-c：指定是集群连接[root@localhost 7001]# ./redis-cli -h 192.168.1.110 -p 7001 -c192.168.1.110:7001> set test hello-> Redirected to slot [6918] located at 10.39.12.237:7003OK10.39.12.237:7003> get test"hello"10.39.12.237:7003> 

6.查看集群信息

10.39.12.237:7003> cluster infocluster_state:okcluster_slots_assigned:16384cluster_slots_ok:16384cluster_slots_pfail:0cluster_slots_fail:0cluster_known_nodes:6cluster_size:6cluster_current_epoch:6cluster_my_epoch:3cluster_stats_messages_sent:5335cluster_stats_messages_received:5335

7.查看集群节点

10.39.12.237:7003> cluster nodes534dd9ab4c373f3a145c1f5838003e141f46a608 10.39.12.237:7005 slave  - 0 1513258673541 5 connected 10923-136524a8a2716ed36415bd82b91dc3662ca56d999bced 10.39.12.237:7001 master - 0 1513258676590 1 connected 0-2730f22201dcb909630c98105099311aa1742280237e 10.39.12.237:7003 myself,master - 0 0 3 connected 5461-8191a090f5b3e28a5ce7b237f2872f40a39f0213c5d7 10.39.12.237:7002 master - 0 1513258677607 2 connected 2731-54609f2df6a9df345ab2314fc5a109c70a6e031e7297 10.39.12.237:7004 slave  - 0 1513258678623 4 connected 8192-10922310cb997e025ac596fb690413f7d06acc8f671e3 10.39.12.237:7006 slave  - 0 1513258679640 6 connected 13653-16383

8.维护节点

1）添加主节点集群创建成功后可以向集群中添加节点，下面是添加一个master主节点，添加7007结点作为新节点。[root@localhost redis-cluster]# ./redis-trib.rb add-node 10.39.12.237:7007 10.39.12.237:70012）hash槽重新分配添加完主节点需要对主节点进行hash槽分配，这样该主节才可以存储数据。查看集群中槽占用情况，redis集群有16384个槽，集群中的每个结点分配自已槽，通过查看集群结点可以看到槽占用情况。127.0.0.1:7001> cluster nodes给刚添加的7007结点分配槽第一步：连接上集群（连接集群中任意一个可用结点都行）[root@localhost redis-cluster]# ./redis-trib.rb  reshard 10.39.12.237:7001第二步：输入要分配的槽数量

输入：100，表示要分配100个槽第三步：输入接收槽的结点id

输入：e4ccb3217026fcff20f5d4110883a5ac2d614b6dPS：这里准备给7007分配槽，通过cluster nodes查看7007结点id为：e4ccb3217026fcff20f5d4110883a5ac2d614b6d第四步：输入源结点id

第五步：输入yes开始移动槽到目标结点id

3）添加从节点集群创建成功后可以向集群中添加节点，下面是添加一个slave从节点，添加7008从结点，将7008作为7007的从结点。命令：./redis-trib.rb add-node --slave --master-id 主节点id 新节点的ip和端口 旧节点ip和端口[root@localhost redis-cluster]# ./redis-trib.rb add-node --slave --master-id 36c36b350c8bb38dcdded0daa21151b0eaae38d5 10.39.12.237:7008 10.39.12.237:7007注意：如果原来该结点在集群中的配置信息已经生成到cluster-config-file指定的配置文件中（如果cluster-config-file没有指定则默认为nodes.conf），这时可能会报错：[ERR] Node 10.39.12.237:7008 is not empty. Either the node already knows other nodes (check with CLUSTER NODES) or contains some key in database 0.解决方法是删除生成的配置文件nodes.conf，删除后再执行./redis-trib.rb add-node指令4）删除结点[root@localhost redis-cluster]#./redis-trib.rb del-node 10.39.12.237:7002 4b45eb75c8b428fbd77ab979b85080146a9bc017删除已经占有hash槽的结点会失败，报错如下：[ERR] Node 10.39.12.237:7002 is not empty! Reshard data away and try again.需要将该结点占用的hash槽分配出去

9.Jedis连接集群

1）防火墙配置[root@localhost /]# vim /etc/sysconfig/iptables

2）代码实现->1.创建JedisCluster类连接redis集群。    @Test    public void jedisCluster(){        Set<HostAndPort> nodes = new HashSet<>();        nodes.add(new HostAndPort("10.39.12.237", 7001));        nodes.add(new HostAndPort("10.39.12.237", 7002));        nodes.add(new HostAndPort("10.39.12.237", 7003));        nodes.add(new HostAndPort("10.39.12.237", 7004));        nodes.add(new HostAndPort("10.39.12.237", 7005));        nodes.add(new HostAndPort("10.39.12.237", 7006));        //JedisCluster对象,在系统中是单例存在        JedisCluster jedisCluster = new JedisCluster(nodes);        jedisCluster.set("s8", "hello world");        String result = jedisCluster.get("s8");        System.out.println(result);        jedisCluster.close();    }->2.使用spring配置applicationContext.xml<bean id="jedisCluster" class="redis.clients.jedis.JedisCluster">    <constructor-arg index="0">        <set>            <bean class="redis.clients.jedis.HostAndPort">                <constructor-arg index="0" value="10.39.12.237"></constructor-arg>                <constructor-arg index="1" value="7001"></constructor-arg>            </bean>            <bean class="redis.clients.jedis.HostAndPort">                <constructor-arg index="0" value="10.39.12.237"></constructor-arg>                <constructor-arg index="1" value="7002"></constructor-arg>            </bean>            <bean class="redis.clients.jedis.HostAndPort">                <constructor-arg index="0" value="10.39.12.237"></constructor-arg>                <constructor-arg index="1" value="7003"></constructor-arg>            </bean>            <bean class="redis.clients.jedis.HostAndPort">                <constructor-arg index="0" value="10.39.12.237"></constructor-arg>                <constructor-arg index="1" value="7004"></constructor-arg>            </bean>            <bean class="redis.clients.jedis.HostAndPort">                <constructor-arg index="0" value="10.39.12.237"></constructor-arg>                <constructor-arg index="1" value="7005"></constructor-arg>            </bean>            <bean class="redis.clients.jedis.HostAndPort">                <constructor-arg index="0" value="10.39.12.237"></constructor-arg>                <constructor-arg index="1" value="7006"></constructor-arg>            </bean>        </set>    </constructor-arg>    <constructor-arg index="1" ref="jedisPoolConfig"></constructor-arg> </bean>测试代码:    @Test    public void jedisClusterSpring(){        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:/config/applicationContext.xml");        JedisCluster jedis = (JedisCluster) applicationContext.getBean("jedisCluster");        jedis.set("s9", "welcome");        String result = jedis.get("s9");        System.out.println(result);    }