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 java.io.Serializable;
021import java.nio.charset.StandardCharsets;
022
023import org.apache.logging.log4j.core.Filter;
024import org.apache.logging.log4j.core.Layout;
025import org.apache.logging.log4j.core.LogEvent;
026import org.apache.logging.log4j.core.appender.AbstractAppender;
027import org.apache.logging.log4j.core.appender.AppenderLoggingException;
028import org.apache.logging.log4j.core.config.Property;
029import org.apache.logging.log4j.core.config.plugins.Plugin;
030import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
031import org.apache.logging.log4j.core.config.plugins.PluginElement;
032import org.apache.logging.log4j.core.config.plugins.PluginFactory;
033import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
034
035/**
036 * Sends log events to an Apache Kafka topic.
037 */
038@Plugin(name = "Kafka", category = "Core", elementType = "appender", printObject = true)
039public final class KafkaAppender extends AbstractAppender {
040
041    /**
042     * 
043     */
044    private static final long serialVersionUID = 1L;
045    @PluginFactory
046    public static KafkaAppender createAppender(
047            @PluginElement("Layout") final Layout<? extends Serializable> layout,
048            @PluginElement("Filter") final Filter filter,
049            @Required(message = "No name provided for KafkaAppender") @PluginAttribute("name") final String name,
050            @PluginAttribute(value = "ignoreExceptions", defaultBoolean = true) final boolean ignoreExceptions,
051            @Required(message = "No topic provided for KafkaAppender") @PluginAttribute("topic") final String topic,
052            @PluginElement("Properties") final Property[] properties) {
053        final KafkaManager kafkaManager = new KafkaManager(name, topic, properties);
054        return new KafkaAppender(name, layout, filter, ignoreExceptions, kafkaManager);
055    }
056
057    private final KafkaManager manager;
058
059    private KafkaAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter, final boolean ignoreExceptions, final KafkaManager manager) {
060        super(name, filter, layout, ignoreExceptions);
061        this.manager = manager;
062    }
063
064    @Override
065    public void append(final LogEvent event) {
066        if (event.getLoggerName().startsWith("org.apache.kafka")) {
067            LOGGER.warn("Recursive logging from [{}] for appender [{}].", event.getLoggerName(), getName());
068        } else {
069            try {
070                if (getLayout() != null) {
071                    manager.send(getLayout().toByteArray(event));
072                } else {
073                    manager.send(event.getMessage().getFormattedMessage().getBytes(StandardCharsets.UTF_8));
074                }
075            } catch (final Exception e) {
076                LOGGER.error("Unable to write to Kafka [{}] for appender [{}].", manager.getName(), getName(), e);
077                throw new AppenderLoggingException("Unable to write to Kafka in appender: " + e.getMessage(), e);
078            }
079        }
080    }
081
082    @Override
083    public void start() {
084        super.start();
085        manager.startup();
086    }
087
088    @Override
089    public void stop() {
090        super.stop();
091        manager.release();
092    }
093
094}