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使用 kafkat 在线扩缩容 kafka replicas

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07/31
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本文档应用环境为 kafka-0.8.2.0, 其余版本请先行测试

场景

线上很多 kafka 的 topic 的副本数为1,这样的设置丧失了 kafka 高可用的特性,所以我们需要把 topic 的副本数至少设置为2(当前3台 kafka)

我们使用 kafkat 这个工具,这个工具是 ruby 写的,所以我们先安装 ruby 环境

参考 https://ruby-china.org/wiki/rvm-guide

这时候你应该已经由了 gem 命令

继续参考https://github.com/airbnb/kafkat 把 kafkat 装上, 并配置好你的 kafka 环境参数到 ~/.kafkatcfg

实操

我们修改 topic 的 replicas 为2

[root@001 kafka]# kafkat partitions IM_APP_BINSPECT_MSG_TOPIC
Topic       Partition   Leader      Replicas                        ISRs
IM_APP_BINSPECT_MSG_TOPIC   0       2       [2]                         [2]
IM_APP_BINSPECT_MSG_TOPIC   1       3       [3]                         [3]
IM_APP_BINSPECT_MSG_TOPIC   2       1       [1]                         [1]
IM_APP_BINSPECT_MSG_TOPIC   3       2       [2]                         [2]
IM_APP_BINSPECT_MSG_TOPIC   4       3       [3]                         [3]
IM_APP_BINSPECT_MSG_TOPIC   5       1       [1]                         [1]
IM_APP_BINSPECT_MSG_TOPIC   6       2       [2]                         [2]
IM_APP_BINSPECT_MSG_TOPIC   7       3       [3]                         [3]
IM_APP_BINSPECT_MSG_TOPIC   8       1       [1]                         [1]
IM_APP_BINSPECT_MSG_TOPIC   9       2       [2]                         [2]
IM_APP_BINSPECT_MSG_TOPIC   10      3       [3]                         [3]
IM_APP_BINSPECT_MSG_TOPIC   11      1       [1]                         [1]
IM_APP_BINSPECT_MSG_TOPIC   12      2       [2]                         [2]
IM_APP_BINSPECT_MSG_TOPIC   13      3       [3]                         [3]
IM_APP_BINSPECT_MSG_TOPIC   14      1       [1]                         [1]
IM_APP_BINSPECT_MSG_TOPIC   15      2       [2]                         [2]
IM_APP_BINSPECT_MSG_TOPIC   16      3       [3]                         [3]
IM_APP_BINSPECT_MSG_TOPIC   17      1       [1]                         [1]
IM_APP_BINSPECT_MSG_TOPIC   18      2       [2]                         [2]
IM_APP_BINSPECT_MSG_TOPIC   19      3       [3]                         [3]
[root@001 kafka]# kafkat set-replication-factor IM_APP_BINSPECT_MSG_TOPIC --newrf 2 --brokers 1,2,3
This operation executes the following assignments:
Topic       Partition   Replicas
IM_APP_BINSPECT_MSG_TOPIC   0       [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   1       [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   2       [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   3       [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   4       [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   5       [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   6       [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   7       [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   8       [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   9       [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   10      [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   11      [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   12      [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   13      [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   14      [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   15      [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   16      [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   17      [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   18      [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   19      [3, 2]
Proceed (y/n)?
y
Beginning.
Started.
[root@001 kafka]# kafkat partitions IM_APP_BINSPECT_MSG_TOPIC
Topic       Partition   Leader      Replicas                        ISRs
IM_APP_BINSPECT_MSG_TOPIC   0       2       [2, 1]                          [2]
IM_APP_BINSPECT_MSG_TOPIC   1       3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   2       1       [1, 3]                          [1]
IM_APP_BINSPECT_MSG_TOPIC   3       2       [2, 1]                          [2]
IM_APP_BINSPECT_MSG_TOPIC   4       3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   5       1       [1, 3]                          [1]
IM_APP_BINSPECT_MSG_TOPIC   6       2       [2, 1]                          [2]
IM_APP_BINSPECT_MSG_TOPIC   7       3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   8       1       [1, 3]                          [1]
IM_APP_BINSPECT_MSG_TOPIC   9       2       [2, 1]                          [2]
IM_APP_BINSPECT_MSG_TOPIC   10      3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   11      1       [1, 3]                          [1]
IM_APP_BINSPECT_MSG_TOPIC   12      2       [2, 1]                          [2]
IM_APP_BINSPECT_MSG_TOPIC   13      3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   14      1       [1, 3]                          [1]
IM_APP_BINSPECT_MSG_TOPIC   15      2       [2, 1]                          [2]
IM_APP_BINSPECT_MSG_TOPIC   16      3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   17      1       [1, 3]                          [1]
IM_APP_BINSPECT_MSG_TOPIC   18      2       [2, 1]                          [2]
IM_APP_BINSPECT_MSG_TOPIC   19      3       [3, 2]                          [3]

解释

上面一共执行了3个命令

  1. kafkat partitions IM_APP_BINSPECT_MSG_TOPIC   查看 topic 的分区情况
  2. kafkat set-replication-factor IM_APP_BINSPECT_MSG_TOPIC --newrf 2 --brokers 1,2,3   重新设置副本数为2  --newrf 2  , 你有几个 broker就在--brokers 后面指定
  3. kafkat partitions IM_APP_BINSPECT_MSG_TOPIC    检查是否生效

根据 topic 数据量最后完成的时间也不同(大概几分钟)

这是最后的完成情况

[root@001 kafka]# kafkat partitions IM_APP_BINSPECT_MSG_TOPIC
Topic       Partition   Leader      Replicas                        ISRs
IM_APP_BINSPECT_MSG_TOPIC   0       2       [2, 1]                          [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   1       3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   2       1       [1, 3]                          [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   3       2       [2, 1]                          [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   4       3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   5       1       [1, 3]                          [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   6       2       [2, 1]                          [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   7       3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   8       1       [1, 3]                          [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   9       2       [2, 1]                          [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   10      3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   11      1       [1, 3]                          [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   12      2       [2, 1]                          [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   13      3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   14      1       [1, 3]                          [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   15      2       [2, 1]                          [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   16      3       [3, 2]                          [3, 2]
IM_APP_BINSPECT_MSG_TOPIC   17      1       [1, 3]                          [1, 3]
IM_APP_BINSPECT_MSG_TOPIC   18      2       [2, 1]                          [2, 1]
IM_APP_BINSPECT_MSG_TOPIC   19      3       [3, 2]                          [3, 2]