Honor logback.debug property and write Logback statuses to console

Closes gh-16876

Author: wilkinsona

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/logback/DebugLogbackConfigurator.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2012-2019 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
+ *
+ *      https://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.logback;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.LoggerContext;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.Appender;
+import ch.qos.logback.core.pattern.Converter;
+import ch.qos.logback.core.spi.LifeCycle;
+import ch.qos.logback.core.status.InfoStatus;
+import ch.qos.logback.core.status.Status;
+
+/**
+ * Custom {@link LogbackConfigurator} used to add {@link Status Statuses} when Logback
+ * debugging is enabled.
+ *
+ * @author Andy Wilkinson
+ */
+class DebugLogbackConfigurator extends LogbackConfigurator {
+
+	DebugLogbackConfigurator(LoggerContext context) {
+		super(context);
+	}
+
+	@Override
+	@SuppressWarnings("rawtypes")
+	public void conversionRule(String conversionWord, Class<? extends Converter> converterClass) {
+		info("Adding conversion rule of type '" + converterClass.getName() + "' for word '" + conversionWord);
+		super.conversionRule(conversionWord, converterClass);
+	}
+
+	@Override
+	public void appender(String name, Appender<?> appender) {
+		info("Adding appender '" + appender + "' named '" + name + "'");
+		super.appender(name, appender);
+	}
+
+	@Override
+	public void logger(String name, Level level, boolean additive, Appender<ILoggingEvent> appender) {
+		info("Configuring logger '" + name + "' with level '" + level + "'. Additive: " + additive);
+		if (appender != null) {
+			info("Adding appender '" + appender + "' to logger '" + name + "'");
+		}
+		super.logger(name, level, additive, appender);
+	}
+
+	@Override
+	public void start(LifeCycle lifeCycle) {
+		info("Starting '" + lifeCycle + "'");
+		super.start(lifeCycle);
+	}
+
+	private void info(String message) {
+		getContext().getStatusManager().add(new InfoStatus(message, this));
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackConfigurator.java

@@ -28,7 +28,6 @@
 import ch.qos.logback.core.pattern.Converter;
 import ch.qos.logback.core.spi.ContextAware;
 import ch.qos.logback.core.spi.LifeCycle;
-import ch.qos.logback.core.spi.PropertyContainer;
 
 import org.springframework.util.Assert;
 
@@ -47,7 +46,7 @@ class LogbackConfigurator {
 		this.context = context;
 	}
 
-	public PropertyContainer getContext() {
+	public LoggerContext getContext() {
 		return this.context;
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackLoggingSystem.java

@@ -33,7 +33,9 @@
 import ch.qos.logback.classic.util.ContextInitializer;
 import ch.qos.logback.core.joran.spi.JoranException;
 import ch.qos.logback.core.spi.FilterReply;
+import ch.qos.logback.core.status.OnConsoleStatusListener;
 import ch.qos.logback.core.status.Status;
+import ch.qos.logback.core.util.StatusListenerConfigHelper;
 import org.slf4j.ILoggerFactory;
 import org.slf4j.Logger;
 import org.slf4j.Marker;
@@ -125,7 +127,12 @@ public void initialize(LoggingInitializationContext initializationContext, Strin
 	protected void loadDefaults(LoggingInitializationContext initializationContext, LogFile logFile) {
 		LoggerContext context = getLoggerContext();
 		stopAndReset(context);
-		LogbackConfigurator configurator = new LogbackConfigurator(context);
+		boolean debug = Boolean.getBoolean("logback.debug");
+		if (debug) {
+			StatusListenerConfigHelper.addOnConsoleListenerInstance(context, new OnConsoleStatusListener());
+		}
+		LogbackConfigurator configurator = debug ? new DebugLogbackConfigurator(context)
+				: new LogbackConfigurator(context);
 		Environment environment = initializationContext.getEnvironment();
 		context.putProperty(LoggingSystemProperties.LOG_LEVEL_PATTERN,
 				environment.resolvePlaceholders("${logging.pattern.level:${LOG_LEVEL_PATTERN:%5p}}"));

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemTests.java

@@ -460,6 +460,35 @@ public void testDateformatPatternProperty() {
 				.containsPattern("\\d{4}-\\d{2}\\-\\d{2}T\\d{2}:\\d{2}:\\d{2}");
 	}
 
+	@Test
+	public void noDebugOutputIsProducedByDefault() {
+		System.clearProperty("logback.debug");
+		this.loggingSystem.beforeInitialize();
+		File file = new File(tmpDir(), "logback-test.log");
+		LogFile logFile = getLogFile(file.getPath(), null);
+		this.loggingSystem.initialize(this.initializationContext, null, logFile);
+		String output = this.output.toString().trim();
+		System.out.println(output);
+		assertThat(output).doesNotContain("LevelChangePropagator").doesNotContain("SizeAndTimeBasedFNATP");
+	}
+
+	@Test
+	public void logbackDebugPropertyIsHonored() {
+		System.setProperty("logback.debug", "true");
+		try {
+			this.loggingSystem.beforeInitialize();
+			File file = new File(tmpDir(), "logback-test.log");
+			LogFile logFile = getLogFile(file.getPath(), null);
+			this.loggingSystem.initialize(this.initializationContext, null, logFile);
+			String output = this.output.toString().trim();
+			assertThat(output).contains("LevelChangePropagator").contains("SizeAndTimeBasedFNATP")
+					.contains("DebugLogbackConfigurator");
+		}
+		finally {
+			System.clearProperty("logback.debug");
+		}
+	}
+
 	private static Logger getRootLogger() {
 		ILoggerFactory factory = StaticLoggerBinder.getSingleton().getLoggerFactory();
 		LoggerContext context = (LoggerContext) factory;