如何在Kafka中修改Topic的preferred replica

操作背景

假如topic test.example中partition 0的replicas为[0,4]，则0为preferred replica，应该成为leader。 
这时我们期望4为preferred replica，并变成leader。

执行步骤如下：

1.查看当前的topic详细信息： 
lizhitao@users-MacBook-Pro-2:~$ ./bin/kafka-topics.sh –zookeeper 192.168.2.225:2183/config/mobile/mq –describe –topic test.example 
Topic:test.example PartitionCount:12 ReplicationFactor:2 Configs: 
Topic: test.example Partition: 0 Leader: 0 Replicas: 0,4 Isr: 0,4 
Topic: test.example Partition: 1 Leader: 1 Replicas: 1,5 Isr: 1,5 
Topic: test.example Partition: 2 Leader: 2 Replicas: 2,3 Isr: 2,3 
Topic: test.example Partition: 3 Leader: 0 Replicas: 0,4 Isr: 0,4 
Topic: test.example Partition: 4 Leader: 1 Replicas: 1,5 Isr: 1,5 
Topic: test.example Partition: 5 Leader: 2 Replicas: 2,3 Isr: 2,3 
Topic: test.example Partition: 6 Leader: 0 Replicas: 0,4 Isr: 0,4 
Topic: test.example Partition: 7 Leader: 1 Replicas: 1,5 Isr: 1,5 
Topic: test.example Partition: 8 Leader: 2 Replicas: 2,3 Isr: 2,3 
Topic: test.example Partition: 9 Leader: 0 Replicas: 0,4 Isr: 0,4 
Topic: test.example Partition: 10 Leader: 1 Replicas: 1,5 Isr: 1,5 
Topic: test.example Partition: 11 Leader: 2 Replicas: 2,3 Isr: 2,3

2.修改replicas的顺序 
lizhitao@users-MacBook-Pro-2:~$ cat partitions-to-move.json 
{ 
“partitions”: [ 
{ 
“topic”: “test.example”, 
“partition”: 0, 
“replicas”: [ 
4, 
0 
] 
} 
], 
“version”: 1 
}

lizhitao@users-MacBook-Pro-2:~$ ./bin/kafka-reassign-partitions.sh –zookeeper 192.168.2.225:2183/config/mobile/mq –reassignment-json-file partitions-to-move.json –execute

3.更改leader 
lizhitao@users-MacBook-Pro-2:~$ cat topicPartitionList.json 
{ 
“partitions”: 
[ 
{“topic”: “test.example”, “partition”: 0} 
] 
}

lizhitao@users-MacBook-Pro-2:~$ ./bin/kafka-preferred-replica-election.sh –zookeeper 192.168.2.225:2183/config/mobile/mq –path-to-json-file topicPartitionList.json

4.检查replicas leader切换情况 
lizhitao@users-MacBook-Pro-2:~$ ./bin/kafka-topics.sh –zookeeper 192.168.2.225:2183/config/mobile/mq –describe –topic test.example 
Topic:test.example PartitionCount:12 ReplicationFactor:2 Configs: 
Topic: test.example Partition: 0 Leader: 4 Replicas: 4,0 Isr: 0,4 
Topic: test.example Partition: 1 Leader: 1 Replicas: 1,5 Isr: 1,5 
Topic: test.example Partition: 2 Leader: 2 Replicas: 2,3 Isr: 2,3 
Topic: test.example Partition: 3 Leader: 0 Replicas: 0,4 Isr: 0,4 
Topic: test.example Partition: 4 Leader: 1 Replicas: 1,5 Isr: 1,5 
Topic: test.example Partition: 5 Leader: 2 Replicas: 2,3 Isr: 2,3 
Topic: test.example Partition: 6 Leader: 0 Replicas: 0,4 Isr: 0,4 
Topic: test.example Partition: 7 Leader: 1 Replicas: 1,5 Isr: 1,5 
Topic: test.example Partition: 8 Leader: 2 Replicas: 2,3 Isr: 2,3 
Topic: test.example Partition: 9 Leader: 0 Replicas: 0,4 Isr: 0,4 
Topic: test.example Partition: 10 Leader: 1 Replicas: 1,5 Isr: 1,5 
Topic: test.example Partition: 11 Leader: 2 Replicas: 2,3 Isr: 2,3