Redis 內置客戶端 redis-cli 通過 --cluster 選項集成了多個 Redis 集羣管理工具， 這些工具可以執行創建集羣、向集羣中添加或移除節點、對集羣實施重分片以及負載均衡等操作， 它們每一個都非常強大：
$ redis-cli --cluster help
Cluster Manager Commands:
create host1:port1 ... hostN:portN
--cluster-replicas <arg>
check host:port
info host:port
fix host:port
reshard host:port
--cluster-from <arg>
--cluster-to <arg>
--cluster-slots <arg>
--cluster-yes
--cluster-timeout <arg>
--cluster-pipeline <arg>
rebalance host:port
--cluster-weight <node1=w1...nodeN=wN>
--cluster-use-empty-masters
--cluster-timeout <arg>
--cluster-simulate
--cluster-pipeline <arg>
--cluster-threshold <arg>
add-node new_host:new_port existing_host:existing_port
--cluster-slave
--cluster-master-id <arg>
del-node host:port node_id
call host:port command arg arg .. arg
set-timeout host:port milliseconds
import host:port
--cluster-from <arg>
--cluster-copy
--cluster-replace
help
For check, fix, reshard, del-node, set-timeout you can specify the host and port of any working node in the cluster.
本文將對上述工具的其中一些進行介紹， 幫助大家初步地瞭解這些工具的基本用法。
創建集羣的工作可以通過 create 命令來完成， 用戶只需要給定各個節點的地址以及想要設置的從服務器數量即可。 比如說， 通過執行以下命令， 我們可以創建出一個由三個主節點和三個從節點組成的集羣：
$ redis-cli --cluster create 127.0.0.1:30001 127.0.0.1:30002 127.0.0.1:30003 127.0.0.1:30004 127.0.0.1:30005 127.0.0.1:30006 --cluster-replicas 1 >>> Performing hash slots allocation on 6 nodes... Master[0] -> Slots 0 - 5460 Master[1] -> Slots 5461 - 10922 Master[2] -> Slots 10923 - 16383 Adding replica 127.0.0.1:30004 to 127.0.0.1:30001 Adding replica 127.0.0.1:30005 to 127.0.0.1:30002 Adding replica 127.0.0.1:30006 to 127.0.0.1:30003 >>> Trying to optimize slaves allocation for anti-affinity [WARNING] Some slaves are in the same host as their master M: 4979f8583676c46039672fb7319e917e4b303707 127.0.0.1:30001 slots:[0-5460] (5461 slots) master M: 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 127.0.0.1:30002 slots:[5461-10922] (5462 slots) master M: 07e230805903e4e1657743a2e4d8811a59e2f32f 127.0.0.1:30003 slots:[10923-16383] (5461 slots) master S: 4788fd4d92387fc5d38a2cd12f0c0d80fc0f6609 127.0.0.1:30004 replicates 4979f8583676c46039672fb7319e917e4b303707 S: b45a7f4355ea733a3177b89654c10f9c31092e92 127.0.0.1:30005 replicates 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 S: 7c56ffba63e3758bc4c2e9b6a55caf294bb21650 127.0.0.1:30006 replicates 07e230805903e4e1657743a2e4d8811a59e2f32f Can 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 cluster Waiting for the cluster to join .. >>> Performing Cluster Check (using node 127.0.0.1:30001) M: 4979f8583676c46039672fb7319e917e4b303707 127.0.0.1:30001 slots:[0-5460] (5461 slots) master 1 additional replica(s) S: 4788fd4d92387fc5d38a2cd12f0c0d80fc0f6609 127.0.0.1:30004 slots: (0 slots) slave replicates 4979f8583676c46039672fb7319e917e4b303707 S: b45a7f4355ea733a3177b89654c10f9c31092e92 127.0.0.1:30005 slots: (0 slots) slave replicates 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 S: 7c56ffba63e3758bc4c2e9b6a55caf294bb21650 127.0.0.1:30006 slots: (0 slots) slave replicates 07e230805903e4e1657743a2e4d8811a59e2f32f M: 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 127.0.0.1:30002 slots:[5461-10922] (5462 slots) master 1 additional replica(s) M: 07e230805903e4e1657743a2e4d8811a59e2f32f 127.0.0.1:30003 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.
通過執行 info 命令， 用戶可以看到集羣包含的主從節點數量， 以及集羣中的鍵、槽分佈信息：
$ redis-cli --cluster info 127.0.0.1:30001 127.0.0.1:30001 (4979f858...) -> 1 keys | 5461 slots | 1 slaves. 127.0.0.1:30002 (4ff303d9...) -> 4 keys | 5462 slots | 1 slaves. 127.0.0.1:30003 (07e23080...) -> 3 keys | 5461 slots | 1 slaves. [OK] 8 keys in 3 masters. 0.00 keys per slot on average.
添加節點/移除節點
在擁有了集羣之後， 用戶就可以通過執行 add-node 命令或者 del-node 命令， 向集羣裏面添加新節點又或者移除已有的節點。
比如說， 通過執行以下命令， 我們可以把節點 30007 添加至集羣當中：在此我向大家推薦一個架構學習交流裙。交流學習裙號：821169538，裏面會分享一些資深架構師錄製的視頻錄像
redis-cli --cluster add-node 127.0.0.1:30007 127.0.0.1:30001 >>> Adding node 127.0.0.1:30007 to cluster 127.0.0.1:30001 >>> Performing Cluster Check (using node 127.0.0.1:30001) ... [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. >>> Send CLUSTER MEET to node 127.0.0.1:30007 to make it join the cluster. [OK] New node added correctly.
又或者通過執行以下命令， 將 ID 爲 e1971e... 的節點 30007 移出集羣：
redis-cli --cluster del-node 127.0.0.1:30001 e1971eef02709cf4698a6fcb09935a910982ab3b >>> Removing node e1971eef02709cf4698a6fcb09935a910982ab3b from cluster 127.0.0.1:30001 >>> Sending CLUSTER FORGET messages to the cluster... >>> SHUTDOWN the node.
通過執行 reshard 命令， 用戶可以將指定數量的槽從一個節點遷移至另一個節點。 比如說， 通過執行以下命令， 我們可以將 ID 爲 4979f... 的節點 30001 目前負責的其中 10 個槽轉交給 ID 爲 1cd87d... 的節點 30007 負責：
$ redis-cli --cluster reshard 127.0.0.1:30001 --cluster-from 4979f8583676c46039672fb7319e917e4b303707 --cluster-to 1cd87d132101893b7aa2b81cf333b2f7be9e1b75 --cluster-slots 10
>>> Performing Cluster Check (using node 127.0.0.1:30001)
M: 4979f8583676c46039672fb7319e917e4b303707 127.0.0.1:30001
slots:[0-5460] (5461 slots) master
1 additional replica(s)
S: 4788fd4d92387fc5d38a2cd12f0c0d80fc0f6609 127.0.0.1:30004
slots: (0 slots) slave
replicates 4979f8583676c46039672fb7319e917e4b303707
S: b45a7f4355ea733a3177b89654c10f9c31092e92 127.0.0.1:30005
slots: (0 slots) slave
replicates 4ff303d96f5c7436ce8ce2fa6e306272e82cd454
M: 1cd87d132101893b7aa2b81cf333b2f7be9e1b75 127.0.0.1:30007
slots: (0 slots) master
S: 7c56ffba63e3758bc4c2e9b6a55caf294bb21650 127.0.0.1:30006
slots: (0 slots) slave
replicates 07e230805903e4e1657743a2e4d8811a59e2f32f
M: 4ff303d96f5c7436ce8ce2fa6e306272e82cd454 127.0.0.1:30002
slots:[5461-10922] (5462 slots) master
1 additional replica(s)
M: 07e230805903e4e1657743a2e4d8811a59e2f32f 127.0.0.1:30003
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.
Ready to move 10 slots.
Source nodes:
M: 4979f8583676c46039672fb7319e917e4b303707 127.0.0.1:30001
slots:[0-5460] (5461 slots) master
1 additional replica(s)
Destination node:
M: 1cd87d132101893b7aa2b81cf333b2f7be9e1b75 127.0.0.1:30007
slots: (0 slots) master
Resharding plan:
Moving slot 0 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 1 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 2 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 3 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 4 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 5 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 6 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 7 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 8 from 4979f8583676c46039672fb7319e917e4b303707
Moving slot 9 from 4979f8583676c46039672fb7319e917e4b303707
Do you want to proceed with the proposed reshard plan (yes/no)? yes
Moving slot 0 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 1 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 2 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 3 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 4 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 5 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 6 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 7 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 8 from 127.0.0.1:30001 to 127.0.0.1:30007:
Moving slot 9 from 127.0.0.1:30001 to 127.0.0.1:30007:
當集羣中各個節點的槽配置趨於不均衡的時候， 各個節點負擔的載荷就可能會出現區別， 並導致某些節點超負荷運行， 而某些節點則長時間空置。 爲了解決這個問題， 用戶可以通過執行 rebalance 命令， 讓各個節點負責的槽數量重新回到平均狀態。
比如說， 對於以下這個由三個節點組成， 並且三個節點分別負責 2000 、 11384 和 3000 個槽的集羣來說：
$ redis-cli --cluster info 127.0.0.1:30001 127.0.0.1:30001 (61d1f17b...) -> 0 keys | 2000 slots | 1 slaves. 127.0.0.1:30002 (101fbae9...) -> 0 keys | 11384 slots | 1 slaves. 127.0.0.1:30003 (31822e0a...) -> 0 keys | 3000 slots | 1 slaves. [OK] 0 keys in 3 masters. 0.00 keys per slot on average.
我們可以通過執行以下命令來重新分配各個節點負責的槽：
$ redis-cli --cluster rebalance 127.0.0.1:30001 >>> Performing Cluster Check (using node 127.0.0.1:30001) [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered. >>> Rebalancing across 3 nodes. Total weight = 3.00 Moving 3462 slots from 127.0.0.1:30002 to 127.0.0.1:30001 #####...##### Moving 2461 slots from 127.0.0.1:30002 to 127.0.0.1:30003 #####...#####
在複雜均衡操作執行完畢之後， 集羣各個節點負責的槽數量將趨於平均， 這樣它們各自負擔的載荷也會重新回到平均狀態：
$ redis-cli --cluster info 127.0.0.1:30001 127.0.0.1:30001 (61d1f17b...) -> 0 keys | 5462 slots | 1 slaves. 127.0.0.1:30002 (101fbae9...) -> 0 keys | 5461 slots | 1 slaves. 127.0.0.1:30003 (31822e0a...) -> 0 keys | 5461 slots | 1 slaves. [OK] 0 keys in 3 masters. 0.00 keys per slot on average.
在集羣的所有節點中執行命令
如果用戶想要對集羣中的所有節點執行同一個命令， 那麼可以通過 call 命令來完成。 比如說， 通過執行以下命令， 用戶就可以讓集羣中的每個節點都執行 DBSIZE 命令， 從而得到各個節點各自的數據庫大小：
$ redis-cli --cluster call 127.0.0.1:30001 DBSIZE >>> Calling DBSIZE 127.0.0.1:30001: (integer) 0 127.0.0.1:30004: (integer) 0 127.0.0.1:30005: (integer) 3 127.0.0.1:30006: (integer) 0 127.0.0.1:30002: (integer) 3 127.0.0.1:30003: (integer) 0
好的， 關於 redis-cli --cluster 選項的簡單介紹就到此結束了， 希望這些介紹可以幫助大家更好地瞭解到這些命令。 大家有興趣的話， 也可以以此爲起點， 更加深入地學習這些命令。