Redis Cluster 自动化安装，扩容和缩容
之前写过一篇基于python的redis集群自动化安装的实现，基于纯命令的集群实现还是相当繁琐的，因此官方提供了redis-trib.rb这个工具
虽然官方的的redis-trib.rb提供了集群创建、 检查、 修复、均衡等命令行工具，之所个人接受不了redis-trib.rb，原因在于redis-trib.rb无法自定义实现集群中节点的主从关系。
比如ABCDEF6个节点，在创建集群的过程中必然要明确指定哪些是主，哪些是从，主从对应关系，可惜通过redis-trib.rb无法自定义控制，参考如下截图。
更多的时候，是需要明确指明哪些机器作为主节点，哪些作为从节点，redis-trib.rb做不到自动控制集群中的哪些机器（实例）作为主，哪些机器（实例）作为从。
如果使用redis-trib.rb，还需要解决ruby的环境依赖，因此个人不太接受使用redis-trib.rb搭建集群。
引用《Redis开发与运维》里面的原话：
如果部署节点使用不同的IP地址， redis-trib.rb会尽可能保证主从节点不分配在同一机器下， 因此会重新排序节点列表顺序。
节点列表顺序用于确定主从角色， 先主节点之后是从节点。
这说明：使用redis-trib.rb是无法人为地完全控制主从节点的分配的。
后面redis 5.0版本的Redis-cli --cluster已经实现了集群的创建，无需依赖redis-trib.rb，包括ruby环境，redis 5.0版本Redis-cli --cluster本身已经实现了集群等相关功能
但是基于纯命令本身还是比较复杂的,尤其是在较为复杂的生产环境，通过手动方式来创建集群，扩容或者缩容，会存在一系列的手工操作，以及一些不安全因素。
所以，自动化的集群创建 ，扩容以及缩容是有必要的。
测试环境
这里基于python3，以redis-cli --cluster命令为基础，实现redis自动化集群，自动化扩容，自动化缩容
测试环境以单机多实例为示例，一共8个节点，
1，自动化集群的创建，6各节点（10001~10006）创建为3主（10001~10002）3从（10004~10006）的集群
2，集群的自动化扩容，增加新节点10007为主节点，同时添加10008为10007节点的slave节点
3，集群的自动化缩容，与2相反，移除集群中的10007以及其slave的10008节点
Redis集群创建
集群的本质是执行两组命令，一个是将主节点加入到集群中，一个是依次对主节点添加slave节点。
但是期间会涉及到找到各个节点id的逻辑，因此手动实现的话，比较繁琐。
主要命令如下：
################# create cluster #################
redis-cli --cluster create 127.0.0.1:10001 127.0.0.1:10002 127.0.0.1:10003 -a ****** --cluster-yes
################# add slave nodes #################
redis-cli --cluster add-node 127.0.0.1:10004 127.0.0.1:10001 --cluster-slave --cluster-master-id 6164025849a8ff9297664fc835bc851af5004f61 -a ******
redis-cli --cluster add-node 127.0.0.1:10005 127.0.0.1:10002 --cluster-slave --cluster-master-id 64e634307bdc339b503574f5a77f1b156c021358 -a ******
redis-cli --cluster add-node 127.0.0.1:10006 127.0.0.1:10003 --cluster-slave --cluster-master-id 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a -a ******
这里使用python创建的过程中打印出来redis-cli --cluster 命令的日志信息
[root@JD redis_install]# python3 create_redis_cluster.py ################# flush master/slave slots ################# ################# create cluster ################# redis-cli --cluster create 127.0.0.1:10001 127.0.0.1:10002 127.0.0.1:10003 -a ****** --cluster-yes Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe. >>> Performing hash slots allocation on 3 nodes... Master[0] -> Slots 0 - 5460 Master[1] -> Slots 5461 - 10922 Master[2] -> Slots 10923 - 16383 M: 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001 slots:[0-5460] (5461 slots) master M: 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002 slots:[5461-10922] (5462 slots) master M: 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003 slots:[10923-16383] (5461 slots) master >>> 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 127.0.0.1:10001) M: 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001 slots:[0-5460] (5461 slots) master M: 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003 slots:[10923-16383] (5461 slots) master M: 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002 slots:[5461-10922] (5462 slots) master [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. 0 ################# add slave nodes ################# redis-cli --cluster add-node 127.0.0.1:10004 127.0.0.1:10001 --cluster-slave --cluster-master-id 6164025849a8ff9297664fc835bc851af5004f61 -a ****** Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe. >>> Adding node 127.0.0.1:10004 to cluster 127.0.0.1:10001 >>> Performing Cluster Check (using node 127.0.0.1:10001) M: 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001 slots:[0-5460] (5461 slots) master M: 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003 slots:[10923-16383] (5461 slots) master M: 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002 slots:[5461-10922] (5462 slots) master [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. >>> Send CLUSTER MEET to node 127.0.0.1:10004 to make it join the cluster. Waiting for the cluster to join >>> Configure node as replica of 127.0.0.1:10001. [OK] New node added correctly. 0 redis-cli --cluster add-node 127.0.0.1:10005 127.0.0.1:10002 --cluster-slave --cluster-master-id 64e634307bdc339b503574f5a77f1b156c021358 -a ****** Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe. >>> Adding node 127.0.0.1:10005 to cluster 127.0.0.1:10002 >>> Performing Cluster Check (using node 127.0.0.1:10002) M: 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002 slots:[5461-10922] (5462 slots) master S: 026f0179631f50ca858d46c2b2829b3af71af2c8 127.0.0.1:10004 slots: (0 slots) slave replicates 6164025849a8ff9297664fc835bc851af5004f61 M: 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003 slots:[10923-16383] (5461 slots) master M: 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001 slots:[0-5460] (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. >>> Send CLUSTER MEET to node 127.0.0.1:10005 to make it join the cluster. Waiting for the cluster to join >>> Configure node as replica of 127.0.0.1:10002. [OK] New node added correctly. 0 redis-cli --cluster add-node 127.0.0.1:10006 127.0.0.1:10003 --cluster-slave --cluster-master-id 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a -a ****** Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe. >>> Adding node 127.0.0.1:10006 to cluster 127.0.0.1:10003 >>> Performing Cluster Check (using node 127.0.0.1:10003) M: 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003 slots:[10923-16383] (5461 slots) master M: 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002 slots:[5461-10922] (5462 slots) master 1 additional replica(s) S: 23e1871c4e1dc1047ce567326e74a6194589146c 127.0.0.1:10005 slots: (0 slots) slave replicates 64e634307bdc339b503574f5a77f1b156c021358 M: 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001 slots:[0-5460] (5461 slots) master 1 additional replica(s) S: 026f0179631f50ca858d46c2b2829b3af71af2c8 127.0.0.1:10004 slots: (0 slots) slave replicates 6164025849a8ff9297664fc835bc851af5004f61 [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. >>> Send CLUSTER MEET to node 127.0.0.1:10006 to make it join the cluster. Waiting for the cluster to join >>> Configure node as replica of 127.0.0.1:10003. [OK] New node added correctly. 0 ################# cluster nodes info: ################# 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003@20003 myself,master - 0 1575947748000 53 connected 10923-16383 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002@20002 master - 0 1575947748000 52 connected 5461-10922 23e1871c4e1dc1047ce567326e74a6194589146c 127.0.0.1:10005@20005 slave 64e634307bdc339b503574f5a77f1b156c021358 0 1575947746000 52 connected 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001@20001 master - 0 1575947748103 51 connected 0-5460 026f0179631f50ca858d46c2b2829b3af71af2c8 127.0.0.1:10004@20004 slave 6164025849a8ff9297664fc835bc851af5004f61 0 1575947749000 51 connected 9f265545ebb799d2773cfc20c71705cff9d733ae 127.0.0.1:10006@20006 slave 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 0 1575947749105 53 connected [root@JD redis_install]#
Redis集群扩容
redis扩容主要分为两步：
1，增加主节点，同时为主节点增加从节点。
2，重新分配slot到新增加的master节点上。
主要命令如下：
增加主节点到集群中
redis-cli --cluster add-node 127.0.0.1:10007 127.0.0.1:10001 -a ******
为增加的主节点添加从节点
redis-cli --cluster add-node 127.0.0.1:10008 127.0.0.1:10007 --cluster-slave --cluster-master-id 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 -a ******
重新分片slot
############################ execute reshard #########################################
redis-cli -a redis@password --cluster reshard 127.0.0.1:10001 --cluster-from 6164025849a8ff9297664fc835bc851af5004f61 --cluster-to 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
############################ execute reshard #########################################
redis-cli -a redis@password --cluster reshard 127.0.0.1:10002 --cluster-from 64e634307bdc339b503574f5a77f1b156c021358 --cluster-to 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
############################ execute reshard #########################################
redis-cli -a redis@password --cluster reshard 127.0.0.1:10003 --cluster-from 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a --cluster-to 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
################# cluster nodes info: #################
026f0179631f50ca858d46c2b2829b3af71af2c8 127.0.0.1:10004@20004 slave 6164025849a8ff9297664fc835bc851af5004f61 0 1575960493000 64 connected
9f265545ebb799d2773cfc20c71705cff9d733ae 127.0.0.1:10006@20006 slave 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 0 1575960493849 66 connected
64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002@20002 master - 0 1575960494852 65 connected 6826-10922
23e1871c4e1dc1047ce567326e74a6194589146c 127.0.0.1:10005@20005 slave 64e634307bdc339b503574f5a77f1b156c021358 0 1575960492000 65 connected
4854375c501c3dbfb4e2d94d50e62a47520c4f12 127.0.0.1:10008@20008 slave 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 0 1575960493000 67 connected
8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003@20003 master - 0 1575960493000 66 connected 12288-16383
3645e00a8ec3a902bd6effb4fc20c56a00f2c982 127.0.0.1:10007@20007 myself,master - 0 1575960493000 67 connected 0-1364 5461-6825 10923-12287
6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001@20001 master - 0 1575960492848 64 connected 1365-5460
可见新加的节点成功重新分配了slot，集群扩容成功。
这里有几个需要注意的两个问题，如果是自动化安装的话：
1，add-node之后（不管是柱节点还是从节点），要sleep足够长的时间（这里是20秒），让集群中所有的节点都meet到新节点，否则会扩容失败
2，新节点的reshard之后要sleep足够长的时间（这里是20秒），否则继续reshard其他节点的slot会导致上一个reshared失败
整个过程如下
[root@JD redis_install]# python3 create_redis_cluster.py #########################cleanup instance################################# #########################add node into cluster################################# redis-cli --cluster add-node 127.0.0.1:10007 127.0.0.1:10001 -a redis@password Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe. >>> Adding node 127.0.0.1:10007 to cluster 127.0.0.1:10001 >>> Performing Cluster Check (using node 127.0.0.1:10001) M: 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001 slots:[0-5460] (5461 slots) master 1 additional replica(s) S: 9f265545ebb799d2773cfc20c71705cff9d733ae 127.0.0.1:10006 slots: (0 slots) slave replicates 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a M: 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003 slots:[10923-16383] (5461 slots) master 1 additional replica(s) S: 026f0179631f50ca858d46c2b2829b3af71af2c8 127.0.0.1:10004 slots: (0 slots) slave replicates 6164025849a8ff9297664fc835bc851af5004f61 S: 23e1871c4e1dc1047ce567326e74a6194589146c 127.0.0.1:10005 slots: (0 slots) slave replicates 64e634307bdc339b503574f5a77f1b156c021358 M: 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002 slots:[5461-10922] (5462 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. >>> Send CLUSTER MEET to node 127.0.0.1:10007 to make it join the cluster. [OK] New node added correctly. 0 redis-cli --cluster add-node 127.0.0.1:10008 127.0.0.1:10007 --cluster-slave --cluster-master-id 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 -a ****** Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe. >>> Adding node 127.0.0.1:10008 to cluster 127.0.0.1:10007 >>> Performing Cluster Check (using node 127.0.0.1:10007) M: 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 127.0.0.1:10007 slots: (0 slots) master S: 026f0179631f50ca858d46c2b2829b3af71af2c8 127.0.0.1:10004 slots: (0 slots) slave replicates 6164025849a8ff9297664fc835bc851af5004f61 S: 9f265545ebb799d2773cfc20c71705cff9d733ae 127.0.0.1:10006 slots: (0 slots) slave replicates 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a M: 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002 slots:[5461-10922] (5462 slots) master 1 additional replica(s) S: 23e1871c4e1dc1047ce567326e74a6194589146c 127.0.0.1:10005 slots: (0 slots) slave replicates 64e634307bdc339b503574f5a77f1b156c021358 M: 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003 slots:[10923-16383] (5461 slots) master 1 additional replica(s) M: 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001 slots:[0-5460] (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. >>> Send CLUSTER MEET to node 127.0.0.1:10008 to make it join the cluster. Waiting for the cluster to join >>> Configure node as replica of 127.0.0.1:10007. [OK] New node added correctly. 0 #########################reshard slots################################# ############################ execute reshard ######################################### redis-cli -a redis@password --cluster reshard 127.0.0.1:10001 --cluster-from 6164025849a8ff9297664fc835bc851af5004f61 --cluster-to 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1 ############################ execute reshard ######################################### redis-cli -a redis@password --cluster reshard 127.0.0.1:10002 --cluster-from 64e634307bdc339b503574f5a77f1b156c021358 --cluster-to 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1 ############################ execute reshard ######################################### redis-cli -a redis@password --cluster reshard 127.0.0.1:10003 --cluster-from 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a --cluster-to 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1 ################# cluster nodes info: ################# 026f0179631f50ca858d46c2b2829b3af71af2c8 127.0.0.1:10004@20004 slave 6164025849a8ff9297664fc835bc851af5004f61 0 1575960493000 64 connected 9f265545ebb799d2773cfc20c71705cff9d733ae 127.0.0.1:10006@20006 slave 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 0 1575960493849 66 connected 64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002@20002 master - 0 1575960494852 65 connected 6826-10922 23e1871c4e1dc1047ce567326e74a6194589146c 127.0.0.1:10005@20005 slave 64e634307bdc339b503574f5a77f1b156c021358 0 1575960492000 65 connected 4854375c501c3dbfb4e2d94d50e62a47520c4f12 127.0.0.1:10008@20008 slave 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 0 1575960493000 67 connected 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003@20003 master - 0 1575960493000 66 connected 12288-16383 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 127.0.0.1:10007@20007 myself,master - 0 1575960493000 67 connected 0-1364 5461-6825 10923-12287 6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001@20001 master - 0 1575960492848 64 connected 1365-5460 [root@JD redis_install]#
Redis集群缩容
缩容按道理是扩容的反向操作.
从这个命令就可以看出来：del-node host:port node_id #删除给定的一个节点，成功后关闭该节点服务。
缩容就缩容了，从集群中移除掉（cluster forget nodeid）某个主节点就行了，为什么还要关闭？因此本文不会采用redis-cli --cluster del-node的方式缩容，而是通过普通命令行来缩容。
这里的自定义缩容实质上分两步
1，将移除的主节点的slot分配回集群中其他节点，这里测试四个主节点缩容为三个主节点，实际上执行命令如下。
2，集群中的节点依次执行cluster forget master_node_id(slave_node_id)
############################ execute reshard #########################################
redis-cli -a ****** --cluster reshard 127.0.0.1:10001 --cluster-from 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-to 6164025849a8ff9297664fc835bc851af5004f61 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
############################ execute reshard #########################################
redis-cli -a ****** --cluster reshard 127.0.0.1:10002 --cluster-from 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-to 64e634307bdc339b503574f5a77f1b156c021358 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
############################ execute reshard #########################################
redis-cli -a ****** --cluster reshard 127.0.0.1:10003 --cluster-from 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-to 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
{'host': '127.0.0.1', 'port': 10001, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10001, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10002, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10002, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10003, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10003, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10004, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10004, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10005, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10005, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10006, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10006, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
完整代码如下
[root@JD redis_install]# python3 create_redis_cluster.py
############################ execute reshard #########################################
redis-cli -a ****** --cluster reshard 127.0.0.1:10001 --cluster-from 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-to 6164025849a8ff9297664fc835bc851af5004f61 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
############################ execute reshard #########################################
redis-cli -a ****** --cluster reshard 127.0.0.1:10002 --cluster-from 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-to 64e634307bdc339b503574f5a77f1b156c021358 --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
############################ execute reshard #########################################
redis-cli -a ****** --cluster reshard 127.0.0.1:10003 --cluster-from 3645e00a8ec3a902bd6effb4fc20c56a00f2c982 --cluster-to 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1
{'host': '127.0.0.1', 'port': 10001, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10001, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10002, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10002, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10003, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10003, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10004, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10004, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10005, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10005, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
{'host': '127.0.0.1', 'port': 10006, 'password': '******'}--->cluster forget 3645e00a8ec3a902bd6effb4fc20c56a00f2c982
{'host': '127.0.0.1', 'port': 10006, 'password': '******'}--->cluster forget 4854375c501c3dbfb4e2d94d50e62a47520c4f12
################# cluster nodes info: #################
23e1871c4e1dc1047ce567326e74a6194589146c 127.0.0.1:10005@20005 slave 64e634307bdc339b503574f5a77f1b156c021358 0 1575968426000 76 connected
026f0179631f50ca858d46c2b2829b3af71af2c8 127.0.0.1:10004@20004 slave 6164025849a8ff9297664fc835bc851af5004f61 0 1575968422619 75 connected
6164025849a8ff9297664fc835bc851af5004f61 127.0.0.1:10001@20001 myself,master - 0 1575968426000 75 connected 0-5460
9f265545ebb799d2773cfc20c71705cff9d733ae 127.0.0.1:10006@20006 slave 8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 0 1575968425000 77 connected
8b75325c59a7242344d0ebe5ee1e0068c66ffa2a 127.0.0.1:10003@20003 master - 0 1575968427626 77 connected 10923-16383
64e634307bdc339b503574f5a77f1b156c021358 127.0.0.1:10002@20002 master - 0 1575968426000 76 connected 5461-10922
[root@JD redis_install]#
其实到这里并没有结束，这里要求缩容之后集群中的所有节点都要成功地执行cluster forget master_node_id(和slave_node_id)
否则其他节点仍然有10007节点的心跳信息，超过1分钟之后，仍旧会将已经踢出集群的10007节点(以及从节点10008)会被添加回来
这就一开始就遇到一个奇葩问题，因为没有在缩容后的集群的slave节点上执行cluster forget，被移除的节点，会不断地被添加回来……。
参考这里：http://www.redis.cn/commands/cluster-forget.html
完整的代码实现如下
import os import time import redis from time import ctime,sleep def create_redis_cluster(list_master_node,list_slave_node): print('################# flush master/slave slots #################') for node in list_master_node: currenrt_conn = redis.StrictRedis(host=node["host"], port=node["port"], password=node["password"], decode_responses=True) currenrt_conn.execute_command('flushall') currenrt_conn.execute_command('cluster reset') for node in list_slave_node: currenrt_conn = redis.StrictRedis(host=node["host"], port=node["port"], password=node["password"], decode_responses=True) #currenrt_conn.execute_command('flushall') currenrt_conn.execute_command('cluster reset') print('################# create cluster #################') master_nodes = '' for node in list_master_node: master_nodes = master_nodes + node["host"] + ':' + str(node["port"]) + ' ' command = "redis-cli --cluster create {0} -a ****** --cluster-yes".format(master_nodes) print(command) msg = os.system(command) print(msg) time.sleep(5) print('################# add slave nodes #################') counter = 0 for node in list_master_node: currenrt_conn = redis.StrictRedis(host=node["host"], port=node["port"], password=node["password"], decode_responses=True) current_master_node = node["host"] + ':' + str(node["port"]) current_slave_node = list_slave_node[counter]["host"] + ':' + str(list_slave_node[counter]["port"]) myid = currenrt_conn.cluster('myid') #slave 节点在前，master节点在后 command = "redis-cli --cluster add-node {0} {1} --cluster-slave --cluster-master-id {2} -a ****** ". format(current_slave_node,current_master_node,myid) print(command) msg = os.system(command) counter = counter + 1 print(msg) # show cluster nodes info time.sleep(10) print("################# cluster nodes info: #################") cluster_nodes = currenrt_conn.execute_command('cluster nodes') print(cluster_nodes) # 返回扩容后，原始节点中，每个主节点需要迁出的slot数量 def get_migrated_slot(list_master_node,n): migrated_slot_count = int(16384/len(list_master_node)) - int(16384/(len(list_master_node)+n)) return migrated_slot_count def redis_cluster_expansion(list_master_node,dict_master_node,dict_slave_node): new_master_node = dict_master_node["host"] + ':' + str(dict_master_node["port"]) new_slave_node = dict_slave_node["host"] + ':' + str(dict_slave_node["port"]) print("#########################cleanup instance#################################") new_master_conn = redis.StrictRedis(host=dict_master_node["host"], port=dict_master_node["port"], password=dict_master_node["password"], decode_responses=True) new_master_conn.execute_command('flushall') new_master_conn.execute_command('cluster reset') new_master_id = new_master_conn.cluster('myid') new_slave_conn = redis.StrictRedis(host=dict_slave_node["host"], port=dict_slave_node["port"], password=dict_slave_node["password"], decode_responses=True) new_slave_conn.execute_command('cluster reset') new_slave_id = new_slave_conn.cluster('myid') #new_slave_conn.execute_command('slaveof no one') # 判断新增的节点是否归属于当前集群， # 如果已经归属于当前集群且不占用slot，则先踢出当前集群 cluster forget nodeid,或者终止，给出告警，总之，怎么开心怎么来 # 登录集群中的任何一个节点 cluster_node_conn = redis.StrictRedis(host=list_master_node[0]["host"], port=list_master_node[0]["port"], password=list_master_node[0]["password"],decode_responses=True) dict_node_info = cluster_node_conn.cluster('nodes') '''dict_node_info format example : { '127.0.0.1:10008@20008': {'node_id': '1d10c3ce3b9b7f956a26122980827fe6ce623d22', 'flags': 'master', 'master_id': '-','last_ping_sent': '0', 'last_pong_rcvd': '1575599442000', 'epoch': '8', 'slots': [], 'connected': True}, '127.0.0.1:10002@20002': {'node_id': '64e634307bdc339b503574f5a77f1b156c021358', 'flags': 'master', 'master_id': '-', 'last_ping_sent': '0', 'last_pong_rcvd': '1575599442000', 'epoch': '7', 'slots': [['5461', '10922']], 'connected': True}, '127.0.0.1:10001@20001': {'node_id': '6164025849a8ff9297664fc835bc851af5004f61', 'flags': 'myself,master', 'master_id': '-', 'last_ping_sent': '0', 'last_pong_rcvd': '1575599438000', 'epoch': '6', 'slots': [['0', '5460']], 'connected': True}, '127.0.0.1:10007@20007': {'node_id': '307f589ec7b1eb7bd65c680527afef1e30ce2303', 'flags': 'master', 'master_id': '-', 'last_ping_sent': '0', 'last_pong_rcvd': '1575599443599', 'epoch': '5', 'slots': [], 'connected': True}, '127.0.0.1:10005@20005': {'node_id': '23e1871c4e1dc1047ce567326e74a6194589146c', 'flags': 'slave', 'master_id': '64e634307bdc339b503574f5a77f1b156c021358', 'last_ping_sent': '0', 'last_pong_rcvd': '1575599441000', 'epoch': '7', 'slots': [], 'connected': True}, '127.0.0.1:10004@20004': {'node_id': '026f0179631f50ca858d46c2b2829b3af71af2c8', 'flags': 'slave', 'master_id': '6164025849a8ff9297664fc835bc851af5004f61', 'last_ping_sent': '0', 'last_pong_rcvd': '1575599440000', 'epoch': '6', 'slots': [], 'connected': True}, '127.0.0.1:10006@20006': {'node_id': '9f265545ebb799d2773cfc20c71705cff9d733ae', 'flags': 'slave', 'master_id': '8b75325c59a7242344d0ebe5ee1e0068c66ffa2a', 'last_ping_sent': '0', 'last_pong_rcvd': '1575599442000', 'epoch': '8', 'slots': [], 'connected': True}, '127.0.0.1:10003@20003': {'node_id': '8b75325c59a7242344d0ebe5ee1e0068c66ffa2a', 'flags': 'master', 'master_id': '-', 'last_ping_sent': '0', 'last_pong_rcvd': '1575599442599', 'epoch': '8', 'slots': [['10923', '16383']], 'connected': True} } ''' dict_master_node_in_cluster = 0 dict_slave_node_in_cluster = 0 for key_node in dict_node_info: if new_master_node in key_node: dict_master_node_in_cluster = 1 if len(dict_node_info[key_node]['slots']) > 0: print('error: ' +new_master_node + ' already existing in cluster and alloted slots,execute break......') return if new_slave_node in key_node: dict_slave_node_in_cluster = 1 if len(dict_node_info[key_node]['slots']) > 0: print('error: ' +new_slave_node + ' already existing in cluster and alloted slots,execute break......') return if dict_master_node_in_cluster == 1: for master_node in list_master_node: key_node_conn = redis.StrictRedis(host=master_node["host"], port=master_node["port"],password=master_node["password"], decode_responses=True) print('waring: ' + new_master_node + ' already existing in cluster,cluster forget it......') forget_command = 'cluster forget {0}'.format(new_master_id) key_node_conn.execute_command(forget_command) if dict_slave_node_in_cluster == 1: for master_node in list_master_node: key_node_conn = redis.StrictRedis(host=master_node["host"], port=master_node["port"],password=master_node["password"], decode_responses=True) print('waring: ' + new_slave_node + ' already existing in cluster,forget it......') forget_command = 'cluster forget {0}'.format(new_slave_id) key_node_conn.execute_command(forget_command) print("#########################add node into cluster#################################") try: cluster_node = list_master_node[0]["host"] + ':' + str(list_master_node[0]["port"]) # 1,待加入节点在前，第二个节点为集群中的任意一个节点 add_node_command = " redis-cli --cluster add-node {0} {1} -a ****** ".format(new_master_node,cluster_node) print(add_node_command) print(os.system(add_node_command)) time.sleep(20) # slave 节点在前，master节点在后 add_node_command = " redis-cli --cluster add-node {0} {1} --cluster-slave --cluster-master-id {2} -a ****** ". format(new_slave_node,new_master_node,new_master_id) print(add_node_command) print(os.system(add_node_command)) time.sleep(20) except Exception as e: print('add new node error,the reason is:') print(e) print("#########################reshard slots#################################") migrated_slot_count = get_migrated_slot(list_master_node,1) for node in list_master_node: current_master_conn = redis.StrictRedis(host=node["host"], port=node["port"], password=node["password"], decode_responses=True) current_master_node = node["host"] + ':' + str(node["port"]) current_master_node_id = current_master_conn.cluster('myid') ''' example:3节点-->扩容4节点，每个迁移1365 ''' try: command = r'''redis-cli -a ****** --cluster reshard {0} --cluster-from {1} --cluster-to {2} --cluster-slots {3} --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1 '''. format(current_master_node,current_master_node_id,new_master_id,migrated_slot_count) print('############################ execute reshard #########################################') print(command) msg = os.system(command) time.sleep(20) except Exception as e: print('reshard slots error,the reason is:') print(e) print("################# cluster nodes info: #################") cluster_nodes = new_master_conn.execute_command('cluster nodes') print(cluster_nodes) def redis_cluster_shrinkage(list_master_node,list_slave_node,dict_master_node,dict_slave_node): # 判断新增的节点是否归属于当前集群， # 如果不归属当前集群，则退出 cluster_node_conn = redis.StrictRedis(host=list_master_node[0]["host"], port=list_master_node[0]["port"], password=list_master_node[0]["password"],decode_responses=True) dict_node_info = cluster_node_conn.cluster('nodes') removed_master_node = dict_master_node["host"] + ':' + str(dict_master_node["port"])+'@'+str(dict_master_node["port"]+10000) removed_slave_node = dict_slave_node["host"] + ':' + str(dict_slave_node["port"])+'@'+str(dict_slave_node["port"]+10000) if not removed_master_node in dict_node_info.keys(): print('Error:'+ str(removed_master_node) +' not in cluster,exiting') return if not removed_slave_node in dict_node_info.keys(): print('Error:' + str(removed_slave_node) + ' not in cluster,exiting') return removed_master_conn = redis.StrictRedis(host=dict_master_node["host"], port=dict_master_node["port"], password=dict_master_node["password"], decode_responses=True) removed_master_id = removed_master_conn.cluster('myid') removed_slave_conn = redis.StrictRedis(host=dict_slave_node["host"], port=dict_slave_node["port"], password=dict_slave_node["password"], decode_responses=True) removed_slave_id = removed_slave_conn.cluster('myid') for node in list_master_node: current_master_conn = redis.StrictRedis(host=node["host"], port=node["port"], password=node["password"], decode_responses=True) current_master_node = node["host"] + ':' + str(node["port"]) current_master_node_id = current_master_conn.cluster('myid') ''' 4节点-->缩容3节点，平均将slot归还到三个master节点 ''' try: command = r'''redis-cli -a ****** --cluster reshard {0} --cluster-from {1} --cluster-to {2} --cluster-slots 1365 --cluster-yes --cluster-timeout 50000 --cluster-pipeline 10000 --cluster-replace >/dev/null 2>&1 '''. format(current_master_node, removed_master_id, current_master_node_id) print('############################ execute reshard #########################################') print(command) msg = os.system(command) time.sleep(10) except Exception as e: print('reshard slots error,the reason is:') print(e) removed_master_conn.execute_command('cluster reset') removed_slave_conn.execute_command('cluster reset') for master_node in list_master_node: master_node_conn = redis.StrictRedis(host=master_node["host"], port=master_node["port"],password=master_node["password"], decode_responses=True) foget_master_command = 'cluster forget {0}'.format(removed_master_id) foget_slave_command = 'cluster forget {0}'.format(removed_slave_id) print(str(master_node)+ '--->' + foget_master_command) print(str(master_node)+ '--->' + foget_slave_command) master_node_conn.execute_command(foget_master_command) master_node_conn.execute_command(foget_slave_command) for slave_node in list_slave_node: slave_node_conn = redis.StrictRedis(host=slave_node["host"], port=slave_node["port"], password=slave_node["password"], decode_responses=True) foget_master_command = 'cluster forget {0}'.format(removed_master_id) foget_slave_command = 'cluster forget {0}'.format(removed_slave_id) print(str(slave_node)+ '--->' +foget_master_command) print(str(slave_node)+ '--->' +foget_slave_command) slave_node_conn.execute_command(foget_master_command) slave_node_conn.execute_command(foget_slave_command) print("################# cluster nodes info: #################") cluster_nodes = cluster_node_conn.execute_command('cluster nodes') print(cluster_nodes) if __name__ == '__main__': # master node_1 = {'host': '127.0.0.1', 'port': 10001, 'password': '******'} node_2 = {'host': '127.0.0.1', 'port': 10002, 'password': '******'} node_3 = {'host': '127.0.0.1', 'port': 10003, 'password': '******'} # slave node_4 = {'host': '127.0.0.1', 'port': 10004, 'password': '******'} node_5 = {'host': '127.0.0.1', 'port': 10005, 'password': '******'} node_6 = {'host': '127.0.0.1', 'port': 10006, 'password': '******'} # 主从节点个数必须相同 list_master_node = [node_1, node_2, node_3] list_slave_node = [node_4, node_5, node_6] # 自动化集群创建 #create_redis_cluster(list_master_node,list_slave_node) # 自动化扩容 node_1 = {'host': '127.0.0.1', 'port': 10007, 'password': '******'} node_2 = {'host': '127.0.0.1', 'port': 10008, 'password': '******'} redis_cluster_expansion(list_master_node,node_1,node_2) # 自动化缩容， #redis_cluster_shrinkage(list_master_node,list_slave_node,node_1,node_2)