Redis 叢集管理常見操作一覽
摘要：
Redis 內建客戶端redis-cli
通過--cluster
選項集成了多個 Redis 叢集管理工具，
這些工具可以執行建立叢集、向叢集中新增或移除節點、對叢集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 h...
Redis 內建客戶端redis-cli
通過--cluster
選項集成了多個 Redis 叢集管理工具，
這些工具可以執行建立叢集、向叢集中新增或移除節點、對叢集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: createhost1:port1 ... hostN:portN --cluster-replicas <arg> checkhost:port infohost:port fixhost:port reshardhost:port --cluster-from <arg> --cluster-to <arg> --cluster-slots <arg> --cluster-yes --cluster-timeout <arg> --cluster-pipeline <arg> rebalancehost:port --cluster-weight <node1=w1...nodeN=wN> --cluster-use-empty-masters --cluster-timeout <arg> --cluster-simulate --cluster-pipeline <arg> --cluster-threshold <arg> add-nodenew_host:new_port existing_host:existing_port --cluster-slave --cluster-master-id <arg> del-nodehost:port node_id callhost:port command arg arg .. arg set-timeouthost:port milliseconds importhost: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。
建立叢集的工作可以通過create
命令來完成，
使用者只需要給定各個節點的地址以及想要設定的從伺服器數量即可。
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叢集：
$ 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，
使用者可以看到叢集包含的主從節點數量，
以及叢集中的鍵、槽分佈資訊：
$ 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.
新增節點/移除節點
在擁有了叢集之後，
使用者就可以通過執行add-node
命令或者del-node
命令，
向叢集裡面新增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 新增至叢集當中：
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 為e1971e...
的節點 30007 移出叢集：
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，
使用者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 為4979f...
的節點 30001 目前負責的其中 10 個槽轉交給 ID 為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:
當叢集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執行，
而某些節點則長時間空置。
為了解決這個問題，
使用者可以通過執行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 個槽的叢集來說：
$ 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， 叢集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.
在叢集的所有節點中執行命令
如果使用者想要對叢集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，
使用者就可以讓叢集中的每個節點都執行DBSIZE
命令，
從而得到各個節點各自的資料庫大小：
$ 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，
也可以以此為起點，
更加深入地學習這些命令。
本文節選自尚未釋出的《Redis使用教程》（ofollow,noindex" target="_blank">RedisGuide.com
），
大家有興趣的話也可以關注一下本書，
裡面有關於redis-cli --cluster
工具更深入和更詳細的介紹。
黃健巨集
2018.11.21