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

@@ -43,6 +43,8 @@ content into your application. Rather, pick only the properties that you need.
 	logging.file= # Log file name. For instance, `myapp.log`
 	logging.file.max-history= # Maximum of archive log files to keep. Only supported with the default logback setup.
 	logging.file.max-size= # Maximum log file size. Only supported with the default logback setup.
+	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. Supported only with the default Logback setup.

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

@@ -25,6 +25,8 @@
 import ch.qos.logback.core.Appender;
 import ch.qos.logback.core.ConsoleAppender;
 import ch.qos.logback.core.CoreConstants;
+import ch.qos.logback.core.OutputStreamAppender;
+import ch.qos.logback.core.filter.Filter;
 import ch.qos.logback.core.rolling.RollingFileAppender;
 import ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy;
 import ch.qos.logback.core.util.FileSize;
@@ -120,6 +122,11 @@ private Appender<ILoggingEvent> consoleAppender(LogbackConfigurator config) {
 		encoder.setCharset(StandardCharsets.UTF_8);
 		config.start(encoder);
 		appender.setEncoder(encoder);
+		String[] filterClasses = this.patterns.getProperty("logging.filters.console",
+				String[].class);
+		if (filterClasses != null) {
+			configureFilters(config, appender, filterClasses);
+		}
 		config.appender("CONSOLE", appender);
 		return appender;
 	}
@@ -135,6 +142,11 @@ private Appender<ILoggingEvent> fileAppender(LogbackConfigurator config,
 		config.start(encoder);
 		appender.setFile(logFile);
 		setRollingPolicy(appender, config, logFile);
+		String[] filterClasses = this.patterns.getProperty("logging.filters.file",
+				String[].class);
+		if (filterClasses != null) {
+			configureFilters(config, appender, filterClasses);
+		}
 		config.appender("FILE", appender);
 		return appender;
 	}
@@ -166,4 +178,20 @@ private void setMaxFileSize(
 		}
 	}
 
+	@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-project/spring-boot/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -85,6 +85,18 @@
       "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener",
       "defaultValue": 0
     },
+    {
+      "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-project/spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemTests.java

@@ -26,11 +26,14 @@
 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.ConsoleAppender;
 import ch.qos.logback.core.CoreConstants;
+import ch.qos.logback.core.filter.Filter;
 import ch.qos.logback.core.rolling.RollingFileAppender;
 import ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy;
+import ch.qos.logback.core.spi.FilterReply;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.impl.SLF4JLogFactory;
 import org.hamcrest.Matcher;
@@ -487,6 +490,45 @@ public void testDateformatPatternProperty() {
 				.containsPattern("\\d{4}-\\d{2}\\-\\d{2}T\\d{2}:\\d{2}:\\d{2}");
 	}
 
+	@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 static Logger getRootLogger() {
 		ILoggerFactory factory = StaticLoggerBinder.getSingleton().getLoggerFactory();
 		LoggerContext context = (LoggerContext) factory;
@@ -520,4 +562,24 @@ 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;
+		}
+
+	}
+
 }