关于Flume中Chanel.Selector.header解释

flume内置的ChannelSelector有两种，分别是Replicating和Multiplexing。

Replicating类型的ChannelSelector会针对每一个Event，拷贝到所有的Channel中，这是默认的ChannelSelector。

replicating类型的ChannelSelector例子如下

 1 a1.sources = r1
 2 a1.channels = c1 c2 # 如果有100个Event，那么c1和c2中都会有这100个事件
 3
 4 a1.channels.c1.type = memory
 5 a1.channels.c1.capacity = 1000
 6 a1.channels.c1.transactionCapacity = 100
 7
 8
 9 a1.channels.c2.type = memory
10 a1.channels.c2.capacity = 1000
11 a1.channels.c2.transactionCapacity = 100

Multiplexing类型的ChannelSelector会根据Event中Header中的某个属性决定分发到哪个Channel。

multiplexing类型的ChannelSelector例子如下：

1 a1.sources = r1
2
3 a1.sources.source1.selector.type = multiplexing
4 a1.sources.source1.selector.header = validation # 以header中的validation对应的值作为条件
5 a1.sources.source1.selector.mapping.SUCCESS = c2 # 如果header中validation的值为SUCCESS，使用c2这个channel
6 a1.sources.source1.selector.mapping.FAIL = c1 # 如果header中validation的值为FAIL，使用c1这个channel
7 a1.sources.source1.selector.default = c1 # 默认使用c1这个channel

a1.sources.source1.selector.header = validation # 以header中的validation对应的值作为条件

同理，如下conf文件：

 1 # example.conf: A single-node Flume configuration
 2
 3 # Name the components on this agent
 4 a1.sources = r1
 5 a1.sinks = k1
 6 a1.channels = c1
 7
 8 # Describe/configure the source
 9 a1.sources.r1.type = netcat
10 a1.sources.r1.bind = localhost
11 a1.sources.r1.port = 44444
12
13 a1.sources.r1.interceptors = i1
14 a1.sources.r1.interceptors.i1.type = regex_extractor
15 a1.sources.r1.interceptors.i1.regex = (\\d):(\\d):(\\d)
16 a1.sources.r1.interceptors.i1.serializers = s1 s2 s3
17 a1.sources.r1.interceptors.i1.serializers.s1.name = ip
18 a1.sources.r1.interceptors.i1.serializers.s2.name = domain
19 a1.sources.r1.interceptors.i1.serializers.s3.name = course
20
21 a1.sources.r1.selector.type = multiplexing
22 a1.sources.r1.selector.header = course
23 a1.sources.r1.selector.default = c1
24
25 # Describe the sink
26 a1.sinks.k1.type = logger
27
28 # Use a channel which buffers events in memory
29 a1.channels.c1.type = memory
30 a1.channels.c1.capacity = 1000
31 a1.channels.c1.transactionCapacity = 100
32
33 # Bind the source and sink to the channel
34 a1.sources.r1.channels = c1
35 a1.sinks.k1.channel = c1

source r1中的头部有IP、Domain和cource三种信息，而r1的selector.header = course，表示selector只对IP，Domain和Cource中的Cource进行判断选择，然后再划分channel。