Add option to configure logging filters

This commit introduces `logging.filters.console` and `logging.filters.file` properties which allow configuration of logging filters for default console and file appenders.

Author: vpavic

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -41,6 +41,8 @@ content into your application; rather pick only the properties that you need.
 	logging.config= # Location of the logging configuration file. For instance `classpath:logback.xml` for Logback
 	logging.exception-conversion-word=%wEx # Conversion word used when logging exceptions.
 	logging.file= # Log file name. For instance `myapp.log`
+	logging.filters.console= # Comma-separated list of filter classes to apply to console appender. Only supported with the default logback setup.
+	logging.filters.file= # Comma-separated list of filter classes to apply to file appender. Only supported with the default logback setup.
 	logging.level.*= # Log levels severity mapping. For instance `logging.level.org.springframework=DEBUG`
 	logging.path= # Location of the log file. For instance `/var/log`
 	logging.pattern.console= # Appender pattern for output to the console. Only supported with the default logback setup.

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

@@ -24,6 +24,8 @@
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.Appender;
 import ch.qos.logback.core.ConsoleAppender;
+import ch.qos.logback.core.OutputStreamAppender;
+import ch.qos.logback.core.filter.Filter;
 import ch.qos.logback.core.rolling.FixedWindowRollingPolicy;
 import ch.qos.logback.core.rolling.RollingFileAppender;
 import ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy;
@@ -45,6 +47,7 @@
  *
  * @author Phillip Webb
  * @author Madhura Bhave
+ * @author Vedran Pavic
  * @since 1.1.2
  */
 class DefaultLogbackConfiguration {
@@ -59,13 +62,13 @@ class DefaultLogbackConfiguration {
 
 	private static final Charset UTF8 = Charset.forName("UTF-8");
 
-	private final PropertyResolver patterns;
+	private final PropertyResolver resolver;
 
 	private final LogFile logFile;
 
 	DefaultLogbackConfiguration(LoggingInitializationContext initializationContext,
 			LogFile logFile) {
-		this.patterns = getPatternsResolver(initializationContext.getEnvironment());
+		this.resolver = getPatternsResolver(initializationContext.getEnvironment());
 		this.logFile = logFile;
 	}
 
@@ -119,12 +122,17 @@ private void base(LogbackConfigurator config) {
 	private Appender<ILoggingEvent> consoleAppender(LogbackConfigurator config) {
 		ConsoleAppender<ILoggingEvent> appender = new ConsoleAppender<>();
 		PatternLayoutEncoder encoder = new PatternLayoutEncoder();
-		String logPattern = this.patterns.getProperty("logging.pattern.console",
+		String logPattern = this.resolver.getProperty("logging.pattern.console",
 				CONSOLE_LOG_PATTERN);
 		encoder.setPattern(OptionHelper.substVars(logPattern, config.getContext()));
 		encoder.setCharset(UTF8);
 		config.start(encoder);
 		appender.setEncoder(encoder);
+		String[] filterClasses = this.resolver.getProperty("logging.filters.console",
+				String[].class);
+		if (filterClasses != null) {
+			configureFilters(config, appender, filterClasses);
+		}
 		config.appender("CONSOLE", appender);
 		return appender;
 	}
@@ -133,14 +141,19 @@ private Appender<ILoggingEvent> fileAppender(LogbackConfigurator config,
 			String logFile) {
 		RollingFileAppender<ILoggingEvent> appender = new RollingFileAppender<>();
 		PatternLayoutEncoder encoder = new PatternLayoutEncoder();
-		String logPattern = this.patterns.getProperty("logging.pattern.file",
+		String logPattern = this.resolver.getProperty("logging.pattern.file",
 				FILE_LOG_PATTERN);
 		encoder.setPattern(OptionHelper.substVars(logPattern, config.getContext()));
 		appender.setEncoder(encoder);
 		config.start(encoder);
 		appender.setFile(logFile);
 		setRollingPolicy(appender, config, logFile);
 		setMaxFileSize(appender, config);
+		String[] filterClasses = this.resolver.getProperty("logging.filters.file",
+				String[].class);
+		if (filterClasses != null) {
+			configureFilters(config, appender, filterClasses);
+		}
 		config.appender("FILE", appender);
 		return appender;
 	}
@@ -170,4 +183,20 @@ private void setMaxFileSize(RollingFileAppender<ILoggingEvent> appender,
 		config.start(triggeringPolicy);
 	}
 
+	@SuppressWarnings("unchecked")
+	private void configureFilters(LogbackConfigurator config,
+			OutputStreamAppender appender, String[] filterClasses) {
+		for (String filterClass : filterClasses) {
+			try {
+				Filter filter = (Filter) Class.forName(filterClass).newInstance();
+				config.start(filter);
+				appender.addFilter(filter);
+			}
+			catch (Exception e) {
+				throw new IllegalStateException(
+						"Unable to configure " + filterClass + " logging filter");
+			}
+		}
+	}
+
 }

spring-boot/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -69,6 +69,18 @@
     "description": "Name of the log file. Names can be an exact location or relative to the current directory.",
     "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener"
   },
+  {
+    "name": "logging.filter.console",
+    "type": "java.lang.String[]",
+    "description": "Comma-separated list of filter classes to apply to console appender. Only supported with the default logback setup.",
+    "sourceType": "org.springframework.boot.logging.LoggingApplicationListener"
+  },
+  {
+    "name": "logging.filter.file",
+    "type": "java.lang.String[]",
+    "description": "Comma-separated list of filter classes to apply to file appender. Only supported with the default logback setup.",
+    "sourceType": "org.springframework.boot.logging.LoggingApplicationListener"
+  },
   {
     "name": "logging.level",
     "type": "java.util.Map<java.lang.String,java.lang.String>",

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

@@ -26,7 +26,10 @@
 import ch.qos.logback.classic.Level;
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.LoggerContext;
+import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.classic.spi.LoggerContextListener;
+import ch.qos.logback.core.filter.Filter;
+import ch.qos.logback.core.spi.FilterReply;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.impl.SLF4JLogFactory;
 import org.hamcrest.Matcher;
@@ -66,6 +69,7 @@
  * @author Andy Wilkinson
  * @author Ben Hale
  * @author Madhura Bhave
+ * @author Vedran Pavic
  */
 public class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 
@@ -404,6 +408,45 @@ public void initializationIsOnlyPerformedOnceUntilCleanedUp() throws Exception {
 		verify(listener, times(2)).onReset(loggerContext);
 	}
 
+	@Test
+	public void consoleFiltersProperty() throws Exception {
+		MockEnvironment environment = new MockEnvironment();
+		environment.setProperty("logging.filters.console", HelloFilter.class.getName() +
+				"," + HiFilter.class.getName());
+		LoggingInitializationContext loggingInitializationContext =
+				new LoggingInitializationContext(environment);
+		this.loggingSystem.initialize(loggingInitializationContext, null, null);
+		this.logger.info("Hello world");
+		this.logger.info("Hi world");
+		this.logger.info("Bye world");
+		String output = this.output.toString().trim();
+		assertThat(output).doesNotContain("Hello world");
+		assertThat(output).doesNotContain("Hi world");
+		assertThat(output).contains("Bye world");
+	}
+
+	@Test
+	public void fileFiltersProperty() throws Exception {
+		MockEnvironment environment = new MockEnvironment();
+		environment.setProperty("logging.filters.file", HelloFilter.class.getName() +
+				"," + HiFilter.class.getName());
+		LoggingInitializationContext loggingInitializationContext =
+				new LoggingInitializationContext(environment);
+		this.loggingSystem.initialize(loggingInitializationContext, null,
+				getLogFile(null, tmpDir()));
+		this.logger.info("Hello world");
+		this.logger.info("Hi world");
+		this.logger.info("Bye world");
+		String output = this.output.toString().trim();
+		File file = new File(tmpDir() + "/spring.log");
+		assertThat(output).contains("Hello world");
+		assertThat(output).contains("Hi world");
+		assertThat(output).contains("Bye world");
+		assertThat(getLineWithText(file, "Hello world")).isNull();
+		assertThat(getLineWithText(file, "Hi world")).isNull();
+		assertThat(getLineWithText(file, "Bye world")).isNotEmpty();
+	}
+
 	private String getLineWithText(File file, String outputSearch) throws Exception {
 		return getLineWithText(FileCopyUtils.copyToString(new FileReader(file)),
 				outputSearch);
@@ -419,4 +462,24 @@ private String getLineWithText(String output, String outputSearch) {
 		return null;
 	}
 
+	static class HelloFilter extends Filter<ILoggingEvent> {
+
+		@Override
+		public FilterReply decide(ILoggingEvent event) {
+			return event.getMessage().contains("Hello")
+					? FilterReply.DENY : FilterReply.NEUTRAL;
+		}
+
+	}
+
+	static class HiFilter extends Filter<ILoggingEvent> {
+
+		@Override
+		public FilterReply decide(ILoggingEvent event) {
+			return event.getMessage().contains("Hi")
+					? FilterReply.DENY : FilterReply.NEUTRAL;
+		}
+
+	}
+
 }