Redis Cluster 自動化安裝，擴容和縮容 之前寫過一篇基於python的redis集群自動化安裝的實現，基於純命令的集群實現還是相當繁瑣的，因此官方提供了redis-trib.rb這個工具雖然官方的的redis-trib.rb提供了集群創建、 檢查、 修複、均衡等命令行工具，之所個人接受不 ...
Redis Cluster 自動化安裝，擴容和縮容
之前寫過一篇基於python的redis集群自動化安裝的實現，基於純命令的集群實現還是相當繁瑣的，因此官方提供了redis-trib.rb這個工具
雖然官方的的redis-trib.rb提供了集群創建、 檢查、 修複、均衡等命令行工具，之所個人接受不了redis-trib.rb，原因在於redis-trib.rb無法自定義實現集群中節點的主從關係。
比如ABCDEF6個節點，在創建集群的過程中必然要明確指定哪些是主，哪些是從，主從對應關係，可惜通過redis-trib.rb無法自定義控制，參考如下截圖。
更多的時候，是需要明確指明哪些機器作為主節點，哪些作為從節點，redis-trib.rb做不到自動控制集群中的哪些機器（實例）作為主，哪些機器（實例）作為從。
如果使用redis-trib.rb，還需要解決ruby的環境依賴，因此個人不太接受使用redis-trib.rb搭建集群。
引用《Redis開發與運維》裡面的原話：
如果部署節點使用不同的IP地址， redis-trib.rb會儘可能保證主從節點不分配在同一機器下， 因此會重新排序節點列表順序。
節點列表順序用於確定主從角色， 先主節點之後是從節點。
這說明：使用redis-trib.rb是無法人為地完全控制主從節點的分配的。
後面redis 5.0版本的Redis-cli --cluster已經實現了集群的創建，無需依賴redis-trib.rb，包括ruby環境，redis 5.0版本Redis-cli --cluster本身已經實現了集群等相關功能
但是基於純命令本身還是比較複雜的,尤其是在較為複雜的生產環境，通過手動方式來創建集群，擴容或者縮容，會存在一系列的手工操作，以及一些不安全因素。
所以，自動化的集群創建 ，擴容以及縮容是有必要的。
測試環境
這裡基於python3，以redis-cli --cluster命令為基礎，實現redis自動化集群，自動化擴容，自動化縮容
測試環境以單機多實例為示例，一共8個節點，
1，自動化集群的創建，6各節點（10001~10006）創建為3主（10001~10002）3從（10004~10006）的集群
2，集群的自動化擴容，增加新節點10007為主節點，同時添加10008為10007節點的slave節點
3，集群的自動化縮容，與2相反，移除集群中的10007以及其slave的10008節點
Redis集群創建
集群的本質是執行兩組命令，一個是將主節點加入到集群中，一個是依次對主節點添加slave節點。
但是期間會涉及到找到各個節點id的邏輯，因此手動實現的話，比較繁瑣。
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 ******
這裡使用python創建的過程中列印出來redis-cli --cluster 命令的日誌信息
[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集群擴容
redis擴容主要分為兩步：
1，增加主節點，同時為主節點增加從節點。
2，重新分配slot到新增加的master節點上。
主要命令如下：
增加主節點到集群中
redis-cli --cluster add-node 127.0.0.1:10007 127.0.0.1:10001 -a ******
為增加的主節點添加從節點
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
可見新加的節點成功重新分配了slot，集群擴容成功。
這裡有幾個需要註意的兩個問題，如果是自動化安裝的話：
1，add-node之後（不管是柱節點還是從節點），要sleep足夠長的時間（這裡是20秒），讓集群中所有的節點都meet到新節點，否則會擴容失敗
2，新節點的reshard之後要sleep足夠長的時間（這裡是20秒），否則繼續reshard其他節點的slot會導致上一個reshared失敗
整個過程如下
[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集群縮容
縮容按道理是擴容的反向操作.
從這個命令就可以看出來：del-node host:port node_id #刪除給定的一個節點，成功後關閉該節點服務。
縮容就縮容了，從集群中移除掉（cluster forget nodeid）某個主節點就行了，為什麼還要關閉？因此本文不會採用redis-cli --cluster del-node的方式縮容，而是通過普通命令行來縮容。
這裡的自定義縮容實質上分兩步
1，將移除的主節點的slot分配回集群中其他節點，這裡測試四個主節點縮容為三個主節點，實際上執行命令如下。
2，集群中的節點依次執行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
完整代碼如下
[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]#
其實到這裡並沒有結束，這裡要求縮容之後集群中的所有節點都要成功地執行cluster forget master_node_id(和slave_node_id)
否則其他節點仍然有10007節點的心跳信息，超過1分鐘之後，仍舊會將已經踢出集群的10007節點(以及從節點10008)會被添加回來
這就一開始就遇到一個奇葩問題，因為沒有在縮容後的集群的slave節點上執行cluster forget，被移除的節點，會不斷地被添加回來……。
參考這裡：http://www.redis.cn/commands/cluster-forget.html
完整的代碼實現如下
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 節點在前，master節點在後 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) # 返回擴容後，原始節點中，每個主節點需要遷出的slot數量 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') # 判斷新增的節點是否歸屬於當前集群， # 如果已經歸屬於當前集群且不占用slot，則先踢出當前集群 cluster forget nodeid,或者終止，給出告警，總之，怎麼開心怎麼來 # 登錄集群中的任何一個節點 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'
