将Log4j日志实时写入Kafka

1.创建maven项目，引入依赖

<dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka_2.11</artifactId>
<version>0.11.0.0</version>
</dependency>

<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
</dependency>

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.21</version>
<scope>test</scope>
</dependency>

2.创建log4j.properties

将Log4j日志实时写入Kafka，需要一个核心处理类：

kafka.producer.KafkaLog4jAppender，但是这个类在不同的版本中使用是有差异的，在Kafka0.7和0.8版本中是有这个类的，笔者使用的版本是0.11.0.0，这个版本中是没有这个类的（源码中有，但编译后没有），所有不能直接使用。直接复制下面的类，拷贝到项目中

package com.bigdata.kafka;

import org.apache.kafka.clients.CommonClientConfigs;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.Producer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;
import org.apache.kafka.common.config.ConfigException;
import org.apache.kafka.common.config.SslConfigs;
import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

import java.util.Date;
import java.util.Properties;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

/**
* A log4j appender that produces log messages to Kafka
*/
public class KafkaLog4jAppender extends AppenderSkeleton {

private static final String BOOTSTRAP_SERVERS_CONFIG = ProducerConfig.BOOTSTRAP_SERVERS_CONFIG;
private static final String COMPRESSION_TYPE_CONFIG = ProducerConfig.COMPRESSION_TYPE_CONFIG;
private static final String ACKS_CONFIG = ProducerConfig.ACKS_CONFIG;
private static final String RETRIES_CONFIG = ProducerConfig.RETRIES_CONFIG;
private static final String KEY_SERIALIZER_CLASS_CONFIG = ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG;
private static final String VALUE_SERIALIZER_CLASS_CONFIG = ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG;
private static final String SECURITY_PROTOCOL = CommonClientConfigs.SECURITY_PROTOCOL_CONFIG;
private static final String SSL_TRUSTSTORE_LOCATION = SslConfigs.SSL_TRUSTSTORE_LOCATION_CONFIG;
private static final String SSL_TRUSTSTORE_PASSWORD = SslConfigs.SSL_TRUSTSTORE_PASSWORD_CONFIG;
private static final String SSL_KEYSTORE_TYPE = SslConfigs.SSL_KEYSTORE_TYPE_CONFIG;
private static final String SSL_KEYSTORE_LOCATION = SslConfigs.SSL_KEYSTORE_LOCATION_CONFIG;
private static final String SSL_KEYSTORE_PASSWORD = SslConfigs.SSL_KEYSTORE_PASSWORD_CONFIG;

private String brokerList = null;
private String topic = null;
private String compressionType = null;
private String securityProtocol = null;
private String sslTruststoreLocation = null;
private String sslTruststorePassword = null;
private String sslKeystoreType = null;
private String sslKeystoreLocation = null;
private String sslKeystorePassword = null;

private int retries = 0;
private int requiredNumAcks = Integer.MAX_VALUE;
private boolean syncSend = false;
private Producer<byte[], byte[]> producer = null;

public Producer<byte[], byte[]> getProducer() {
return producer;
}

public String getBrokerList() {
return brokerList;
}

public void setBrokerList(String brokerList) {
this.brokerList = brokerList;
}

public int getRequiredNumAcks() {
return requiredNumAcks;
}

public void setRequiredNumAcks(int requiredNumAcks) {
this.requiredNumAcks = requiredNumAcks;
}

public int getRetries() {
return retries;
}

public void setRetries(int retries) {
this.retries = retries;
}

public String getCompressionType() {
return compressionType;
}

public void setCompressionType(String compressionType) {
this.compressionType = compressionType;
}

public String getTopic() {
return topic;
}

public void setTopic(String topic) {
this.topic = topic;
}

public boolean getSyncSend() {
return syncSend;
}

public void setSyncSend(boolean syncSend) {
this.syncSend = syncSend;
}

public String getSslTruststorePassword() {
return sslTruststorePassword;
}

public String getSslTruststoreLocation() {
return sslTruststoreLocation;
}

public String getSecurityProtocol() {
return securityProtocol;
}

public void setSecurityProtocol(String securityProtocol) {
this.securityProtocol = securityProtocol;
}

public void setSslTruststoreLocation(String sslTruststoreLocation) {
this.sslTruststoreLocation = sslTruststoreLocation;
}

public void setSslTruststorePassword(String sslTruststorePassword) {
this.sslTruststorePassword = sslTruststorePassword;
}

public void setSslKeystorePassword(String sslKeystorePassword) {
this.sslKeystorePassword = sslKeystorePassword;
}

public void setSslKeystoreType(String sslKeystoreType) {
this.sslKeystoreType = sslKeystoreType;
}

public void setSslKeystoreLocation(String sslKeystoreLocation) {
this.sslKeystoreLocation = sslKeystoreLocation;
}

public String getSslKeystoreLocation() {
return sslKeystoreLocation;
}

public String getSslKeystoreType() {
return sslKeystoreType;
}

public String getSslKeystorePassword() {
return sslKeystorePassword;
}

@Override
public void activateOptions() {
// check for config parameter validity
Properties props = new Properties();
if (brokerList != null)
props.put(BOOTSTRAP_SERVERS_CONFIG, brokerList);
if (props.isEmpty())
throw new ConfigException("The bootstrap servers property should be specified");
if (topic == null)
throw new ConfigException("Topic must be specified by the Kafka log4j appender");
if (compressionType != null)
props.put(COMPRESSION_TYPE_CONFIG, compressionType);
if (requiredNumAcks != Integer.MAX_VALUE)
props.put(ACKS_CONFIG, Integer.toString(requiredNumAcks));
if (retries > 0)
props.put(RETRIES_CONFIG, retries);
if (securityProtocol != null && sslTruststoreLocation != null &&
sslTruststorePassword != null) {
props.put(SECURITY_PROTOCOL, securityProtocol);
props.put(SSL_TRUSTSTORE_LOCATION, sslTruststoreLocation);
props.put(SSL_TRUSTSTORE_PASSWORD, sslTruststorePassword);

if (sslKeystoreType != null && sslKeystoreLocation != null &&
sslKeystorePassword != null) {
props.put(SSL_KEYSTORE_TYPE, sslKeystoreType);
props.put(SSL_KEYSTORE_LOCATION, sslKeystoreLocation);
props.put(SSL_KEYSTORE_PASSWORD, sslKeystorePassword);
}
}

props.put(KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.ByteArraySerializer");
props.put(VALUE_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.ByteArraySerializer");
this.producer = getKafkaProducer(props);
LogLog.debug("Kafka producer connected to " + brokerList);
LogLog.debug("Logging for topic: " + topic);
}

protected Producer<byte[], byte[]> getKafkaProducer(Properties props) {
return new KafkaProducer<byte[], byte[]>(props);
}

@Override
protected void append(LoggingEvent event) {
String message = subAppend(event);
LogLog.debug("[" + new Date(event.getTimeStamp()) + "]" + message);
Future<RecordMetadata> response = producer.send(new ProducerRecord<byte[], byte[]>(topic, message.getBytes()));
if (syncSend) {
try {
response.get();
} catch (InterruptedException ex) {
throw new RuntimeException(ex);
} catch (ExecutionException ex) {
throw new RuntimeException(ex);
}
}
}

private String subAppend(LoggingEvent event) {
return (this.layout == null) ? event.getRenderedMessage() : this.layout.format(event);
}

public void close() {
if (!this.closed) {
this.closed = true;
producer.close();
}
}

public boolean requiresLayout() {
return true;
}
}

然后在log4j.properties中配置如下

log4j.rootLogger=INFO,stdout,kafka

log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.target = System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} [%t] [%c] [%p] - %m%n

log4j.appender.kafka = com.bigdata.kafka.KafkaLog4jAppender
log4j.appender.kafka.topic = api_topic
log4j.appender.kafka.brokerList=hadoop000:9092
log4j.appender.kafka.layout=org.apache.log4j.PatternLayout
log4j.appender.kafka.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} [%t] [%c] [%p] - %m%n

3.创建KafkaLog4jApp类

package com.bigdata.kafka;

import org.apache.log4j.Logger;

/**
* 模拟日志产生
*/
public class KafkaLog4jApp {

private static Logger logger = Logger.getLogger(KafkaLog4jApp.class.getName());

public static void main(String[] args) throws Exception {
int index = 0;

while(true) {
Thread.sleep(1000);
logger.info("value is: " + index++);
}
}
}

上述完成后启动Kafka（先启动ZK）

kafka-server-start.sh $KAFKA_HOME/config/server.properties

4.创建topic

[hadoop@Master ~]$ kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic log4jtest
Created topic "log4jtest".
[hadoop@Master ~]$ kafka-topics.sh --describe --zookeeper localhost:2181 --topic log4jtest
Topic:log4jtest PartitionCount:1    ReplicationFactor:1 Configs:
Topic: log4jtest    Partition: 0    Leader: 0   Replicas: 0 Isr: 0

5.启动 Kafka 消费者，运行项目，观察Kafka 消费者的控制台

[hadoop@Master ~]$ kafka-console-consumer.sh --zookeeper localhost:2181 --topic log4jtest
2017-09-28 17:52:15,178 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 0

2017-09-28 17:52:16,331 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 1

2017-09-28 17:52:17,332 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 2

2017-09-28 17:52:18,333 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 3

2017-09-28 17:52:19,336 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 4

2017-09-28 17:52:20,337 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 5

2017-09-28 17:52:21,338 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 6

2017-09-28 17:52:22,339 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 7

2017-09-28 17:52:23,354 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 8

2017-09-28 17:52:24,355 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 9

2017-09-28 17:52:25,418 [main] [com.bigdata.kafka.KafkaLog4jApp] [INFO] - value is: 10