001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache license, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the license for the specific language governing permissions and 015 * limitations under the license. 016 */ 017 018package org.apache.logging.log4j.core.appender.mom.kafka; 019 020import org.apache.logging.log4j.core.Filter; 021import org.apache.logging.log4j.core.Layout; 022import org.apache.logging.log4j.core.LogEvent; 023import org.apache.logging.log4j.core.appender.AbstractAppender; 024import org.apache.logging.log4j.core.appender.AppenderLoggingException; 025import org.apache.logging.log4j.core.config.Property; 026import org.apache.logging.log4j.core.config.plugins.Plugin; 027import org.apache.logging.log4j.core.config.plugins.PluginAttribute; 028import org.apache.logging.log4j.core.config.plugins.PluginElement; 029import org.apache.logging.log4j.core.config.plugins.PluginFactory; 030import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required; 031import org.apache.logging.log4j.core.layout.SerializedLayout; 032import org.apache.logging.log4j.core.util.StringEncoder; 033 034import java.io.Serializable; 035import java.nio.charset.StandardCharsets; 036 037/** 038 * Sends log events to an Apache Kafka topic. 039 */ 040@Plugin(name = "Kafka", category = "Core", elementType = "appender", printObject = true) 041public final class KafkaAppender extends AbstractAppender { 042 043 /** 044 * 045 */ 046 private static final long serialVersionUID = 1L; 047 @PluginFactory 048 public static KafkaAppender createAppender( 049 @PluginElement("Layout") final Layout<? extends Serializable> layout, 050 @PluginElement("Filter") final Filter filter, 051 @Required(message = "No name provided for KafkaAppender") @PluginAttribute("name") final String name, 052 @PluginAttribute(value = "ignoreExceptions", defaultBoolean = true) final boolean ignoreExceptions, 053 @Required(message = "No topic provided for KafkaAppender") @PluginAttribute("topic") final String topic, 054 @PluginElement("Properties") final Property[] properties) { 055 final KafkaManager kafkaManager = new KafkaManager(name, topic, properties); 056 return new KafkaAppender(name, layout, filter, ignoreExceptions, kafkaManager); 057 } 058 059 private final KafkaManager manager; 060 061 private KafkaAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter, final boolean ignoreExceptions, final KafkaManager manager) { 062 super(name, filter, layout, ignoreExceptions); 063 this.manager = manager; 064 } 065 066 @Override 067 public void append(final LogEvent event) { 068 if (event.getLoggerName().startsWith("org.apache.kafka")) { 069 LOGGER.warn("Recursive logging from [{}] for appender [{}].", event.getLoggerName(), getName()); 070 } else { 071 try { 072 Layout<? extends Serializable> layout = getLayout(); 073 byte[] data; 074 if (layout != null) { 075 if (layout instanceof SerializedLayout) { 076 byte[] header = layout.getHeader(); 077 byte[] body = layout.toByteArray(event); 078 data = new byte[header.length + body.length]; 079 System.arraycopy(header, 0, data, 0, header.length); 080 System.arraycopy(body, 0, data, header.length, body.length); 081 } else { 082 data = layout.toByteArray(event); 083 } 084 } else { 085 data = StringEncoder.toBytes(event.getMessage().getFormattedMessage(), StandardCharsets.UTF_8); 086 } 087 manager.send(data); 088 } catch (final Exception e) { 089 LOGGER.error("Unable to write to Kafka [{}] for appender [{}].", manager.getName(), getName(), e); 090 throw new AppenderLoggingException("Unable to write to Kafka in appender: " + e.getMessage(), e); 091 } 092 } 093 } 094 095 @Override 096 public void start() { 097 super.start(); 098 manager.startup(); 099 } 100 101 @Override 102 public void stop() { 103 super.stop(); 104 manager.release(); 105 } 106 107}