Prettify Log4J 2's default output

This commit updates the default output produced when using Log2J 2 to
be similar to the output produced by Logback. It introduces a new
converter for throwables that adds some whitespace around stacktraces
and a color converter that produces ANSI-colored output when enabled
via spring.output.ansi.enabled.

Closes gh-3548

spring-boot-samples/spring-boot-sample-actuator-log4j2/src/main/resources/log4j2.xml

@@ -2,7 +2,7 @@
 <Configuration status="WARN" monitorInterval="30">
     <Properties>
         <Property name="PID">????</Property>
-        <Property name="LOG_PATTERN">[%d{yyyy-MM-dd HH:mm:ss.SSS}] log4j2%X{context} - ${sys:PID} %5p [%t] --- %c{1}: %m%n</Property>
+        <Property name="LOG_PATTERN">%clr{%d{yyyy-MM-dd HH:mm:ss.SSS}}{faint} %clr{%5p} %clr{${sys:PID}}{magenta} %clr{---}{faint} %clr{[%15.15t]}{faint} %clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n%wEx</Property>
     </Properties>
     <Appenders>
         <Console name="Console" target="SYSTEM_OUT" follow="true">

spring-boot/src/main/java/org/springframework/boot/logging/log4j2/ColorConverter.java

+/*
+ * Copyright 2012-2015 the original author or authors.
+ *
+ * Licensed 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.springframework.boot.logging.log4j2;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.LogEvent;
+import org.apache.logging.log4j.core.config.Configuration;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.layout.PatternLayout;
+import org.apache.logging.log4j.core.pattern.ConverterKeys;
+import org.apache.logging.log4j.core.pattern.LogEventPatternConverter;
+import org.apache.logging.log4j.core.pattern.PatternConverter;
+import org.apache.logging.log4j.core.pattern.PatternFormatter;
+import org.apache.logging.log4j.core.pattern.PatternParser;
+import org.springframework.boot.ansi.AnsiColor;
+import org.springframework.boot.ansi.AnsiElement;
+import org.springframework.boot.ansi.AnsiOutput;
+import org.springframework.boot.ansi.AnsiStyle;
+
+/**
+ * Log4j2 {@link LogEventPatternConverter} colors output using the {@link AnsiOutput}
+ * class. A single option 'styling' can be provided to the converter, or if not specified
+ * color styling will be picked based on the logging level.
+ *
+ * @author Vladimir Tsanev
+ * @since 1.3.0
+ */
+@Plugin(name = "color", category = PatternConverter.CATEGORY)
+@ConverterKeys(value = { "clr", "color" })
+public class ColorConverter extends LogEventPatternConverter {
+
+	private static final Map<String, AnsiElement> ELEMENTS;
+	static {
+		Map<String, AnsiElement> elements = new HashMap<String, AnsiElement>();
+		elements.put("faint", AnsiStyle.FAINT);
+		elements.put("red", AnsiColor.RED);
+		elements.put("green", AnsiColor.GREEN);
+		elements.put("yellow", AnsiColor.YELLOW);
+		elements.put("blue", AnsiColor.BLUE);
+		elements.put("magenta", AnsiColor.MAGENTA);
+		elements.put("cyan", AnsiColor.CYAN);
+		ELEMENTS = Collections.unmodifiableMap(elements);
+	}
+
+	private static final Map<Integer, AnsiElement> LEVELS;
+	static {
+		Map<Integer, AnsiElement> levels = new HashMap<Integer, AnsiElement>();
+		levels.put(Level.FATAL.intLevel(), AnsiColor.RED);
+		levels.put(Level.ERROR.intLevel(), AnsiColor.RED);
+		levels.put(Level.WARN.intLevel(), AnsiColor.YELLOW);
+		LEVELS = Collections.unmodifiableMap(levels);
+	}
+
+	private final List<PatternFormatter> formatters;
+
+	private final AnsiElement styling;
+
+	private ColorConverter(List<PatternFormatter> formatters, AnsiElement styling) {
+		super("style", "style");
+		this.formatters = formatters;
+		this.styling = styling;
+	}
+
+	/**
+	 * Creates a new instance of the class. Required by Log4J2.
+	 *
+	 * @param config the configuration
+	 * @param options the options
+	 * @return a new instance, or {@code null} if the options are invalid
+	 */
+	public static ColorConverter newInstance(Configuration config, String[] options) {
+		if (options.length < 1) {
+			LOGGER.error(
+					"Incorrect number of options on style. Expected at least 1, received {}",
+					options.length);
+			return null;
+		}
+		if (options[0] == null) {
+			LOGGER.error("No pattern supplied on style");
+			return null;
+		}
+		PatternParser parser = PatternLayout.createPatternParser(config);
+		List<PatternFormatter> formatters = parser.parse(options[0]);
+
+		AnsiElement element = options.length == 1 ? null : ELEMENTS.get(options[1]);
+		return new ColorConverter(formatters, element);
+	}
+
+	@Override
+	public boolean handlesThrowable() {
+		for (PatternFormatter formatter : this.formatters) {
+			if (formatter.handlesThrowable()) {
+				return true;
+			}
+		}
+		return super.handlesThrowable();
+	}
+
+	@Override
+	public void format(LogEvent event, StringBuilder toAppendTo) {
+		StringBuilder buf = new StringBuilder();
+		for (PatternFormatter formatter : this.formatters) {
+			formatter.format(event, buf);
+		}
+		if (buf.length() > 0) {
+			AnsiElement element = this.styling;
+			if (element == null) {
+				// Assume highlighting
+				element = LEVELS.get(event.getLevel().intLevel());
+				element = (element == null ? AnsiColor.GREEN : element);
+			}
+			appendAnsiString(toAppendTo, buf.toString(), element);
+		}
+	}
+
+	protected void appendAnsiString(StringBuilder toAppendTo, String in,
+			AnsiElement element) {
+		toAppendTo.append(AnsiOutput.toString(element, in));
+	}
+
+}

spring-boot/src/main/java/org/springframework/boot/logging/log4j2/WhitespaceThrowablePatternConverter.java

+/*
+ * Copyright 2012-2015 the original author or authors.
+ *
+ * Licensed 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.springframework.boot.logging.log4j2;
+
+import org.apache.logging.log4j.core.LogEvent;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.pattern.ConverterKeys;
+import org.apache.logging.log4j.core.pattern.PatternConverter;
+import org.apache.logging.log4j.core.pattern.ThrowablePatternConverter;
+
+/**
+ * {@link ThrowablePatternConverter} that adds some additional whitespace around the stack
+ * trace.
+ *
+ * @author Vladimir Tsanev
+ * @since 1.3.0
+ */
+@Plugin(name = "WhitespaceThrowablePatternConverter", category = PatternConverter.CATEGORY)
+@ConverterKeys({ "wEx", "wThrowable", "wException" })
+public class WhitespaceThrowablePatternConverter extends ThrowablePatternConverter {
+
+	private WhitespaceThrowablePatternConverter(String[] options) {
+		super("WhitespaceThrowable", "throwable", options);
+	}
+
+	/**
+	 * Creates a new instance of the class. Required by Log4J2.
+	 *
+	 * @param options pattern options, may be null. If first element is "short", only the
+	 * first line of the throwable will be formatted.
+	 * @return a new {@code WhitespaceThrowablePatternConverter}
+	 */
+	public static WhitespaceThrowablePatternConverter newInstance(String[] options) {
+		return new WhitespaceThrowablePatternConverter(options);
+	}
+
+	@Override
+	public void format(LogEvent event, StringBuilder buffer) {
+		if (event.getThrown() != null) {
+			buffer.append(this.options.getSeparator());
+			super.format(event, buffer);
+			buffer.append(this.options.getSeparator());
+		}
+	}
+
+}

spring-boot/src/main/resources/org/springframework/boot/logging/log4j2/log4j2-file.xml

@@ -2,7 +2,7 @@
 <Configuration status="WARN">
 	<Properties>
 		<Property name="PID">????</Property>
-		<Property name="LOG_PATTERN">[%d{yyyy-MM-dd HH:mm:ss.SSS}] boot%X{context} - ${sys:PID} %5p [%t] --- %c{1}: %m%n</Property>
+		<Property name="LOG_PATTERN">%d{yyyy-MM-dd HH:mm:ss.SSS} %5p ${sys:PID} --- [%t] %-40.40c{1.} : %m%n%wEx</Property>
 	</Properties>
 	<Appenders>
 		<Console name="Console" target="SYSTEM_OUT" follow="true">

spring-boot/src/main/resources/org/springframework/boot/logging/log4j2/log4j2.xml

@@ -2,7 +2,7 @@
 <Configuration status="WARN">
 	<Properties>
 		<Property name="PID">????</Property>
-		<Property name="LOG_PATTERN">[%d{yyyy-MM-dd HH:mm:ss.SSS}] boot%X{context} - ${sys:PID} %5p [%t] --- %c{1}: %m%n</Property>
+		<Property name="LOG_PATTERN">%clr{%d{yyyy-MM-dd HH:mm:ss.SSS}}{faint} %clr{%5p} %clr{${sys:PID}}{magenta} %clr{---}{faint} %clr{[%15.15t]}{faint} %clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n%wEx</Property>
 	</Properties>
 	<Appenders>
 		<Console name="Console" target="SYSTEM_OUT" follow="true">

spring-boot/src/test/java/org/springframework/boot/logging/log4j2/ColorConverterTests.java

+/*
+ * Copyright 2012-2015 the original author or authors.
+ *
+ * Licensed 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.springframework.boot.logging.log4j2;
+
+import org.apache.logging.log4j.Level;
+import org.apache.logging.log4j.core.AbstractLogEvent;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.springframework.boot.ansi.AnsiOutput;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for {@link ColorConverter}.
+ *
+ * @author Vladimir Tsanev
+ */
+public class ColorConverterTests {
+
+	private final String in = "in";
+
+	private TestLogEvent event;
+
+	@BeforeClass
+	public static void setupAnsi() {
+		AnsiOutput.setEnabled(AnsiOutput.Enabled.ALWAYS);
+	}
+
+	@AfterClass
+	public static void resetAnsi() {
+		AnsiOutput.setEnabled(AnsiOutput.Enabled.DETECT);
+	}
+
+	@Before
+	public void setUp() {
+		this.event = new TestLogEvent();
+	}
+
+	private ColorConverter newConverter(String styling) {
+		return ColorConverter.newInstance(null, new String[] { this.in, styling });
+	}
+
+	@Test
+	public void faint() {
+		StringBuilder output = new StringBuilder();
+		newConverter("faint").format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[2min\033[0;39m"));
+	}
+
+	@Test
+	public void red() {
+		StringBuilder output = new StringBuilder();
+		newConverter("red").format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[31min\033[0;39m"));
+	}
+
+	@Test
+	public void green() throws Exception {
+		StringBuilder output = new StringBuilder();
+		newConverter("green").format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[32min\033[0;39m"));
+	}
+
+	@Test
+	public void yellow() throws Exception {
+		StringBuilder output = new StringBuilder();
+		newConverter("yellow").format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[33min\033[0;39m"));
+	}
+
+	@Test
+	public void blue() throws Exception {
+		StringBuilder output = new StringBuilder();
+		newConverter("blue").format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[34min\033[0;39m"));
+	}
+
+	@Test
+	public void magenta() throws Exception {
+		StringBuilder output = new StringBuilder();
+		newConverter("magenta").format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[35min\033[0;39m"));
+	}
+
+	@Test
+	public void cyan() throws Exception {
+		StringBuilder output = new StringBuilder();
+		newConverter("cyan").format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[36min\033[0;39m"));
+	}
+
+	@Test
+	public void highlightFatal() throws Exception {
+		this.event.setLevel(Level.FATAL);
+		StringBuilder output = new StringBuilder();
+		newConverter(null).format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[31min\033[0;39m"));
+	}
+
+	@Test
+	public void highlightError() throws Exception {
+		this.event.setLevel(Level.ERROR);
+		StringBuilder output = new StringBuilder();
+		newConverter(null).format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[31min\033[0;39m"));
+	}
+
+	@Test
+	public void highlightWarn() throws Exception {
+		this.event.setLevel(Level.WARN);
+		StringBuilder output = new StringBuilder();
+		newConverter(null).format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[33min\033[0;39m"));
+	}
+
+	@Test
+	public void highlightDebug() throws Exception {
+		this.event.setLevel(Level.DEBUG);
+		StringBuilder output = new StringBuilder();
+		newConverter(null).format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[32min\033[0;39m"));
+	}
+
+	@Test
+	public void highlightTrace() throws Exception {
+		this.event.setLevel(Level.TRACE);
+		StringBuilder output = new StringBuilder();
+		newConverter(null).format(this.event, output);
+		assertThat(output.toString(), equalTo("\033[32min\033[0;39m"));
+	}
+
+	private static class TestLogEvent extends AbstractLogEvent {
+
+		private Level level;
+
+		@Override
+		public Level getLevel() {
+			return this.level;
+		}
+
+		public void setLevel(Level level) {
+			this.level = level;
+		}
+
+	}
+
+}

spring-boot/src/test/java/org/springframework/boot/logging/log4j2/WhitespaceThrowablePatternConverterTests.java

+package org.springframework.boot.logging.log4j2;
+
+import org.apache.logging.log4j.core.LogEvent;
+import org.apache.logging.log4j.core.impl.Log4jLogEvent;
+import org.junit.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.endsWith;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.startsWith;
+
+/**
+ * Tests for {@link WhitespaceThrowablePatternConverter}.
+ *
+ * @author Vladimir Tsanev
+ */
+public class WhitespaceThrowablePatternConverterTests {
+
+	private static final String LINE_SEPARATOR = System.getProperty("line.separator");
+
+	private final WhitespaceThrowablePatternConverter converter = WhitespaceThrowablePatternConverter
+			.newInstance(new String[] {});
+
+	@Test
+	public void noStackTrace() throws Exception {
+		LogEvent event = Log4jLogEvent.newBuilder().build();
+		StringBuilder builder = new StringBuilder();
+		this.converter.format(event, builder);
+		assertThat(builder.toString(), equalTo(""));
+	}
+
+	@Test
+	public void withStackTrace() throws Exception {
+		LogEvent event = Log4jLogEvent.newBuilder().setThrown(new Exception()).build();
+		StringBuilder builder = new StringBuilder();
+		this.converter.format(event, builder);
+		assertThat(builder.toString(), startsWith(LINE_SEPARATOR));
+		assertThat(builder.toString(), endsWith(LINE_SEPARATOR));
+	}
+
+}