Redis Cluster 简单配置与动态扩容
Redis 3.0 就要自带集群功能了, 去看了一下这里还有官方教程之后, 发现似乎必须用命令行来搞着, 而且官方提供的 redis-trib.rb 要求至少 3 个节点才能建立一个集群, 这规格是向党支部看齐么... 至少 3 个节点这个还是略坑, 而且不能自动添加节点 (难道要我启
Redis 3.0 就要自带集群功能了, 去看了一下这里还有官方教程之后, 发现似乎必须用命令行来搞着, 而且官方提供的 redis-trib.rb 要求至少 3 个节点才能建立一个集群, 这规格是向党支部看齐么...至少 3 个节点这个还是略坑, 而且不能自动添加节点 (难道要我启动个 py 的 subprocess 去掉 ruby?), 于是去看看源代码, 惊讶地发现, 原来限制 3 个节点起步的是 ruby 脚本, 而且调集群加节点平衡负载其实都可以用 redis 命令来完成. 好吧, 那我自己来连 socket 搞总行了吧.
结果一番折腾还真的可行的样子, 于是有了这篇文章和一个简单的工具. 那么首先说说怎么用 redis-cli 来做这些事情.
如何在 redis-cli 手动启动集群呢, 请随意连上一个空的支持集群模式的节点, 然后执行
cluster addslots 0 1 2 ... 16383<br>
... 可是要实打实地从头写到尾的哦. 所以如果可以的话, 手动写个脚本来干这事情吧.不过也可以略过这些步骤, 反正下面看看例子就行, 最后会给出一个 Python 工具来做这些.
接下来的例子中, 假定已经开好了一个集群, 共有 3 个 master 节点. 要在控制台检视这些节点, 请用 redis-cli 随意连上其中一个, 并执行
cluster nodes<br>
e7f4fcc0dd003fc107333a4132a471ad306d5513 127.0.0.1:8001 master - 0 1414033928009 3 connected 0-2729 8192-10921<br>bd239f7dbeaba9541586a708484cdce0ca99aba5 127.0.0.1:8000 master - 0 1414033929011 2 connected 2730-8191<br>787e06e9d96e6a9a3d02c7f3ec14e243882293e9 127.0.0.1:7999 myself,master - 0 0 1 connected 10922-16383<br>
- 节点 ID
- 节点地址
- 节点角色 (master / slave), 如果是当前节点, 还会有个 myself
- 对于 slave 而言, 其 master 节点的 ID
- 最后一次 ping 时间戳
- 最后一次 pong 时间戳
- 节点顺序号
- 节点连接状态
- 之后的所有 : 节点所配给的槽位, 如果槽位连续, 就以 BEGIN-END 表示, 不连续的由空格隔开
cluster meet 命令. 如cluster meet 127.0.0.1 7999<br>
e7f4fcc0dd003fc107333a4132a471ad306d5513 127.0.0.1:8001 master - 0 1414034715486 3 connected 0-2729 8192-10921<br>bd239f7dbeaba9541586a708484cdce0ca99aba5 127.0.0.1:8000 master - 0 1414034714983 2 connected 2730-8191<br>787e06e9d96e6a9a3d02c7f3ec14e243882293e9 127.0.0.1:7999 master - 0 1414034714482 1 connected 10922-16383<br><strong class="ntstrong">a0fa298711f5da94cb8acc0ed913970f7b00c7af 127.0.0.1:8010 myself,master - 0 0 0 connected</strong><br>
set "foo14308" "bar"<br>
第一步, 锁定槽位. 这个操作需要分开进行. 首先用 redis-cli 连上新节点 (上述例子中端口 8010 的那个) 并执行
cluster setslot 7 importing e7f4fcc0dd003fc107333a4132a471ad306d5513<br>
e7f4fcc0dd003fc107333a4132a471ad306d5513 的节点 (也就是 7 号槽位的所有者) 导入 7 号槽.接下来连上 7 号槽位的所有者所在的 8001 端口, 执行
cluster setslot 7 migrating a0fa298711f5da94cb8acc0ed913970f7b00c7af<br>
cluster getkeysinslot 7 10<br>
现在开始手动迁移这些键. 在 8001 端口的客户端上执行
migrate 127.0.0.1 8010 foo14308 0 15000<br>
因为只有这一个键, 所以现在整个槽的迁移已经完成了, 需要告知整个集群 7 号槽位已经被新节点承包了, 官方源码里 这里进行了广播, 在命令行里的话似乎需要逐个连接节点, 执行以下命令
cluster setslot 7 node a0fa298711f5da94cb8acc0ed913970f7b00c7af<br>
在知道以上这些的基础上, 做了一个简单的集群小工具, 能够在单节点上启动集群, 以及将一个新节点加入集群中并且自动平衡槽位. 此 Python 工具已加入 GitHub, 欢迎大家拍砖.
本文出自：http://blog.bitfoc.us, 原文地址：http://blog.bitfoc.us/?p=524, 感谢原作者分享。
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