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The Apache Log4j Implementation
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.logging.log4j.core.layout;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Node;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginElement;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.net.Severity;
import org.apache.logging.log4j.core.util.JsonUtils;
import org.apache.logging.log4j.core.util.KeyValuePair;
import org.apache.logging.log4j.message.Message;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.StringBuilderFormattable;
import org.apache.logging.log4j.util.Strings;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.Map;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.GZIPOutputStream;
/**
* Lays out events in the Graylog Extended Log Format (GELF) 1.1.
*
* This layout compresses JSON to GZIP or ZLIB (the {@code compressionType}) if
* log event data is larger than 1024 bytes (the {@code compressionThreshold}).
* This layout does not implement chunking.
*
*
* Configure as follows to send to a Graylog2 server:
*
*
*
* <Appenders>
* <Socket name="Graylog" protocol="udp" host="graylog.domain.com" port="12201">
* <GelfLayout host="someserver" compressionType="GZIP" compressionThreshold="1024">
* <KeyValuePair key="additionalField1" value="additional value 1"/>
* <KeyValuePair key="additionalField2" value="additional value 2"/>
* </GelfLayout>
* </Socket>
* </Appenders>
*
*
* @see GELF specification
*/
@Plugin(name = "GelfLayout", category = Node.CATEGORY, elementType = Layout.ELEMENT_TYPE, printObject = true)
public final class GelfLayout extends AbstractStringLayout {
public enum CompressionType {
GZIP {
@Override
public DeflaterOutputStream createDeflaterOutputStream(final OutputStream os) throws IOException {
return new GZIPOutputStream(os);
}
},
ZLIB {
@Override
public DeflaterOutputStream createDeflaterOutputStream(final OutputStream os) throws IOException {
return new DeflaterOutputStream(os);
}
},
OFF {
@Override
public DeflaterOutputStream createDeflaterOutputStream(final OutputStream os) throws IOException {
return null;
}
};
public abstract DeflaterOutputStream createDeflaterOutputStream(OutputStream os) throws IOException;
}
private static final char C = ',';
private static final int COMPRESSION_THRESHOLD = 1024;
private static final char Q = '\"';
private static final String QC = "\",";
private static final String QU = "\"_";
private final KeyValuePair[] additionalFields;
private final int compressionThreshold;
private final CompressionType compressionType;
private final String host;
private final boolean includeStacktrace;
public GelfLayout(final String host, final KeyValuePair[] additionalFields, final CompressionType compressionType,
final int compressionThreshold, final boolean includeStacktrace) {
super(StandardCharsets.UTF_8);
this.host = host;
this.additionalFields = additionalFields;
this.compressionType = compressionType;
this.compressionThreshold = compressionThreshold;
this.includeStacktrace = includeStacktrace;
}
@PluginFactory
public static GelfLayout createLayout(
//@formatter:off
@PluginAttribute("host") final String host,
@PluginElement("AdditionalField") final KeyValuePair[] additionalFields,
@PluginAttribute(value = "compressionType",
defaultString = "GZIP") final CompressionType compressionType,
@PluginAttribute(value = "compressionThreshold",
defaultInt = COMPRESSION_THRESHOLD) final int compressionThreshold,
@PluginAttribute(value = "includeStacktrace",
defaultBoolean = true) final boolean includeStacktrace) {
// @formatter:on
return new GelfLayout(host, additionalFields, compressionType, compressionThreshold, includeStacktrace);
}
@Override
public Map getContentFormat() {
return Collections.emptyMap();
}
@Override
public String getContentType() {
return JsonLayout.CONTENT_TYPE + "; charset=" + this.getCharset();
}
@Override
public byte[] toByteArray(final LogEvent event) {
final StringBuilder text = toText(event, getStringBuilder(), false);
final byte[] bytes = getBytes(text.toString());
return compressionType != CompressionType.OFF && bytes.length > compressionThreshold ? compress(bytes) : bytes;
}
@Override
public void encode(final LogEvent event, final ByteBufferDestination destination) {
if (compressionType != CompressionType.OFF) {
super.encode(event, destination);
return;
}
final StringBuilder text = toText(event, getStringBuilder(), true);
final Encoder helper = getStringBuilderEncoder();
helper.encode(text, destination);
}
private byte[] compress(final byte[] bytes) {
try {
final ByteArrayOutputStream baos = new ByteArrayOutputStream(compressionThreshold / 8);
try (final DeflaterOutputStream stream = compressionType.createDeflaterOutputStream(baos)) {
if (stream == null) {
return bytes;
}
stream.write(bytes);
stream.finish();
}
return baos.toByteArray();
} catch (final IOException e) {
StatusLogger.getLogger().error(e);
return bytes;
}
}
@Override
public String toSerializable(final LogEvent event) {
final StringBuilder text = toText(event, getStringBuilder(), false);
return text.toString();
}
private StringBuilder toText(final LogEvent event, final StringBuilder builder, final boolean gcFree) {
builder.append('{');
builder.append("\"version\":\"1.1\",");
builder.append("\"host\":\"");
JsonUtils.quoteAsString(toNullSafeString(host), builder);
builder.append(QC);
builder.append("\"timestamp\":").append(formatTimestamp(event.getTimeMillis())).append(C);
builder.append("\"level\":").append(formatLevel(event.getLevel())).append(C);
if (event.getThreadName() != null) {
builder.append("\"_thread\":\"");
JsonUtils.quoteAsString(event.getThreadName(), builder);
builder.append(QC);
}
if (event.getLoggerName() != null) {
builder.append("\"_logger\":\"");
JsonUtils.quoteAsString(event.getLoggerName(), builder);
builder.append(QC);
}
for (final KeyValuePair additionalField : additionalFields) {
builder.append(QU);
JsonUtils.quoteAsString(additionalField.getKey(), builder);
builder.append("\":\"");
JsonUtils.quoteAsString(toNullSafeString(additionalField.getValue()), builder);
builder.append(QC);
}
for (final Map.Entry entry : event.getContextMap().entrySet()) {
builder.append(QU);
JsonUtils.quoteAsString(entry.getKey(), builder);
builder.append("\":\"");
JsonUtils.quoteAsString(toNullSafeString(entry.getValue()), builder);
builder.append(QC);
}
if (event.getThrown() != null) {
builder.append("\"full_message\":\"");
if (includeStacktrace) {
JsonUtils.quoteAsString(formatThrowable(event.getThrown()), builder);
} else {
JsonUtils.quoteAsString(event.getThrown().toString(), builder);
}
builder.append(QC);
}
builder.append("\"short_message\":\"");
final Message message = event.getMessage();
if (message instanceof CharSequence) {
JsonUtils.quoteAsString(((CharSequence)message), builder);
} else if (gcFree && message instanceof StringBuilderFormattable) {
final StringBuilder messageBuffer = getMessageStringBuilder();
((StringBuilderFormattable)message).formatTo(messageBuffer);
JsonUtils.quoteAsString(messageBuffer, builder);
} else {
JsonUtils.quoteAsString(toNullSafeString(message.getFormattedMessage()), builder);
}
builder.append(Q);
builder.append('}');
return builder;
}
private static final ThreadLocal messageStringBuilder = new ThreadLocal<>();
private static StringBuilder getMessageStringBuilder() {
StringBuilder result = messageStringBuilder.get();
if (result == null) {
result = new StringBuilder(DEFAULT_STRING_BUILDER_SIZE);
messageStringBuilder.set(result);
}
result.setLength(0);
return result;
}
private CharSequence toNullSafeString(final CharSequence s) {
return s == null ? Strings.EMPTY : s;
}
/**
* Non-private to make it accessible from unit test.
*/
static CharSequence formatTimestamp(final long timeMillis) {
if (timeMillis < 1000) {
return "0";
}
final StringBuilder builder = getTimestampStringBuilder();
builder.append(timeMillis);
builder.insert(builder.length() - 3, '.');
return builder;
}
private static final ThreadLocal timestampStringBuilder = new ThreadLocal<>();
private static StringBuilder getTimestampStringBuilder() {
StringBuilder result = timestampStringBuilder.get();
if (result == null) {
result = new StringBuilder(20);
timestampStringBuilder.set(result);
}
result.setLength(0);
return result;
}
/**
* http://en.wikipedia.org/wiki/Syslog#Severity_levels
*/
private int formatLevel(final Level level) {
return Severity.getSeverity(level).getCode();
}
/**
* Non-private to make it accessible from unit test.
*/
static CharSequence formatThrowable(final Throwable throwable) {
// stack traces are big enough to provide a reasonably large initial capacity here
final StringWriter sw = new StringWriter(2048);
final PrintWriter pw = new PrintWriter(sw);
throwable.printStackTrace(pw);
pw.flush();
return sw.getBuffer();
}
}