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Redis 集群管理常見操作

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Redis 內置客戶端 redis-cli 通過 --cluster 選項集成了多個 Redis 集群管理工具, 這些工具可以執行創建集群、向集群中添加或移除節點、對集群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, 幫助大家初步地了解這些工具的基本用法。
創建集群的工作可以通過 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群:

$ 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, 用戶可以看到集群包含的主從節點數量, 以及集群中的鍵、槽分布信息:

$ 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
在擁有了集群之後, 用戶就可以通過執行 add-node 命令或者 del-node 命令, 向集群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 添加至集群當中:

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 移出集群:

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 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:

當集群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。 為了解決這個問題, 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 個槽的集群來說:

$ 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
#####...#####

在復雜均衡操作執行完畢之後, 集群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.

在集群的所有節點中執行命令
如果用戶想要對集群中的所有節點執行同一個命令, 那麽可以通過 call 命令來完成。 比如說, 通過執行以下命令, 用戶就可以讓集群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了解到這些命令。 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。

Redis 集群管理常見操作