Flume实战案例 -- 从HDFS上读取某个文件到本地目录

需求分析

• 我们从HDFS上的特定目录下的文件，读取到本地目录下的特定目录下

• 根据需求，首先定义以下3大要素

  • 数据源组件，即source ——监控HDFS目录文件 : exec 'tail -f'

  • 下沉组件，即sink—— file roll sink

  • 通道组件，即channel——可用file channel 也可以用内存channel

flume配置文件开发

• 配置文件编写：

  cd /bigdata/install/flume-1.9.0/conf/
  vim hdfs2local.conf
  

• 内容如下

  # Name the components on this agent
  a1.sources = r1
  a1.sinks = k1
  a1.channels = c1
  
  # Describe/configure the source
  # 注意：不能往监控目中重复丢同名文件
  a1.sources.r1.type = exec
  a1.sources.r1.command = hdfs dfs -tail -f /hdfs2flume/test/a.txt
  a1.sources.r1.channels = c1
  
  # sink 配置信息
  a1.sinks.k1.type = file_roll
  a1.sinks.k1.channel = c1
  a1.sinks.k1.sink.directory = /bigdata/install/mydata/flume/hdfs2local
  
  a1.sinks.k1.sink.rollInterval = 3600
  a1.sinks.k1.sink.pathManager.prefix = event-
  a1.sinks.k1.sink.serializer = TEXT
  a1.sinks.k1.sink.batchSize = 100
  
  # Use a channel which buffers events in memory
  a1.channels.c1.type = memory
  # channel中存储的event的最大数目
  a1.channels.c1.capacity = 1000
  # 每次传输数据，从source最多获得event的数目或向sink发送的event的最大的数目
  a1.channels.c1.transactionCapacity = 100
  
  # Bind the source and sink to the channel
  a1.sources.r1.channels = c1
  a1.sinks.k1.channel = c1
  

• 准备HDFS文件信息

  vi a.txt
  
  #输入一下内容，保存并推送到HDFS上
  1  zhangsan  21
  2  lisi  22
  3  wangwu  23
  4  zhaoliu  24
  5  guangyunchang  25
  6  gaojianli  27
  
  hdfs dfs -put ./a.txt /hdfs2flume/test/a.txt
  

• 准备本地目录文件夹

  mkdir -p /bigdata/install/mydata/flume/hdfs2local
  

• 启动flume

  cd /bigdata/install/flume-1.9.0
  bin/flume-ng agent -c ./conf -f ./conf/hdfs2local.conf -n a1 -Dflume.root.logger=INFO,console
  

• 追加hdfs上a.txt文件内容，验证本地目录文件夹，如下图