实时流接入数仓，基本在大公司都会有，在Flume1.8以后支持taildir source, 其有以下几个特点，而被广泛使用：
> 1.使用正则表达式匹配目录中的文件名
2.监控的文件中，一旦有数据写入，Flume就会将信息写入到指定的Sink
3.高可靠，不会丢失数据
4.不会对跟踪文件有任何处理，不会重命名也不会删除
5.不支持Windows，不能读二进制文件。支持按行读取文本文件
本文以开源Flume流为例，介绍流接入HDFS ,后面在其上面建立ods层外表。
1.1 taildir source配置
a1.sources.r1.type = TAILDIR
a1.sources.r1.positionFile = /opt/hoult/servers/conf/startlog_position.json
a1.sources.r1.filegroups = f1
a1.sources.r1.filegroups.f1 =/opt/hoult/servers/logs/start/.*log
1.2 hdfs sink 配置
a1.sinks.k1.type = hdfs
a1.sinks.k1.hdfs.path = /user/data/logs/start/logs/start/%Y-%m-%d/
a1.sinks.k1.hdfs.filePrefix = startlog.
# 配置文件滚动方式（文件大小32M）
a1.sinks.k1.hdfs.rollSize = 33554432
a1.sinks.k1.hdfs.rollCount = 0
a1.sinks.k1.hdfs.rollInterval = 0
a1.sinks.k1.hdfs.idleTimeout = 0
a1.sinks.k1.hdfs.minBlockReplicas = 1
# 向hdfs上刷新的event的个数
a1.sinks.k1.hdfs.batchSize = 100
# 使用本地时间
a1.sinks.k1.hdfs.useLocalTimeStamp = true
1.3 Agent的配置
a1.sources = r1
a1.sinks = k1
a1.channels = c1
# taildir source
a1.sources.r1.type = TAILDIR
a1.sources.r1.positionFile = /opt/hoult/servers/conf/startlog_position.json
a1.sources.r1.filegroups = f1
a1.sources.r1.filegroups.f1 = /user/data/logs/start/.*log
# memorychannel
a1.channels.c1.type = memory
a1.channels.c1.capacity = 100000
a1.channels.c1.transactionCapacity = 2000
# hdfs sink
a1.sinks.k1.type = hdfs
a1.sinks.k1.hdfs.path = /opt/hoult/servers/logs/start/%Y-%m-%d/
a1.sinks.k1.hdfs.filePrefix = startlog.
# 配置文件滚动方式（文件大小32M）
a1.sinks.k1.hdfs.rollSize = 33554432
a1.sinks.k1.hdfs.rollCount = 0
a1.sinks.k1.hdfs.rollInterval = 0
a1.sinks.k1.hdfs.idleTimeout = 0
a1.sinks.k1.hdfs.minBlockReplicas = 1
# 向hdfs上刷新的event的个数
a1.sinks.k1.hdfs.batchSize = 1000
# 使用本地时间
a1.sinks.k1.hdfs.useLocalTimeStamp = true
# Bind the source and sink to the channel
a1.sources.r1.channels = c1
a1.sinks.k1.channel = c1
/opt/hoult/servers/conf/flume-log2hdfs.conf
1.4 启动
flume-ng agent --conf-file /opt/hoult/servers/conf/flume-log2hdfs.conf -name a1 -Dflume.roog.logger=INFO,console
export JAVA_OPTS="-Xms4000m -Xmx4000m -Dcom.sun.management.jmxremote"
# 要想使配置文件生效，还要在命令行中指定配置文件目录
flume-ng agent --conf /opt/hoult/servers/flume-1.9.0/conf --conf-file /opt/hoult/servers/conf/flume-log2hdfs.conf -name a1 -Dflume.roog.logger=INFO,console
要$FLUME_HOME/conf/flume-env.sh加下面的参数，否则会报错误如下：
1.5 使用自定义拦截器解决Flume Agent替换本地时间为日志里面的时间戳
使用netcat source → logger sink来测试
# a1是agent的名称。source、channel、sink的名称分别为：r1 c1 k1
a1.sources = r1
a1.channels = c1
a1.sinks = k1
# source
a1.sources.r1.type = netcat
a1.sources.r1.bind = linux121
a1.sources.r1.port = 9999
a1.sources.r1.interceptors = i1
a1.sources.r1.interceptors.i1.type = com.hoult.flume.CustomerInterceptor$Builder
# channel
a1.channels.c1.type = memory
a1.channels.c1.capacity = 10000
a1.channels.c1.transactionCapacity = 100
# sink
a1.sinks.k1.type = logger
# source、channel、sink之间的关系
a1.sources.r1.channels = c1
a1.sinks.k1.channel = c1
拦截器主要代码如下：
public class CustomerInterceptor implements Interceptor {
private static DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");
@Override
public void initialize() {
}
@Override
public Event intercept(Event event) {
// 获得body的内容
String eventBody = new String(event.getBody(), Charsets.UTF_8);
// 获取header的内容
Map headerMap = event.getHeaders();
final String[] bodyArr = eventBody.split("\\s+");
try {
String jsonStr = bodyArr[6];
if (Strings.isNullOrEmpty(jsonStr)) {
return null;
}
// 将 string 转成 json 对象
JSONObject jsonObject = JSON.parseObject(jsonStr);
String timestampStr = jsonObject.getString("time");
//将timestamp 转为时间日期类型（格式 ：yyyyMMdd)
long timeStamp = Long.valueOf(timestampStr);
String date = formatter.format(LocalDateTime.ofInstant(Instant.ofEpochMilli(timeStamp), ZoneId.systemDefault()));
headerMap.put("logtime", date);
event.setHeaders(headerMap);
} catch (Exception e) {
headerMap.put("logtime", "unknown");
event.setHeaders(headerMap);
}
return event;
}
@Override
public List intercept(List events) {
List out = new ArrayList<>();
for (Event event : events) {
Event outEvent = intercept(event);
if (outEvent != null) {
out.add(outEvent);
}
}
return out;
}
@Override
public void close() {
}
public static class Builder implements Interceptor.Builder {
@Override
public Interceptor build() {
return new CustomerInterceptor();
}
@Override
public void configure(Context context) {
}
}
启动
flume-ng agent --conf /opt/hoult/servers/flume-1.9.0/conf --conf-file /opt/hoult/servers/conf/flume-test.conf -name a1 -Dflume.roog.logger=INFO,console
## 测试
telnet linux121 9999
吴邪，小三爷，混迹于后台，大数据，人工智能领域的小菜鸟。
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