Include the application name on each log line when it is available

Update Logback and Log4J2 so that they include the application name on
each log line. If `spring.application.name` had not been set, or if
`logging.include-application-name` is `false` then the name is not
logged.

Closes gh-35593

spring-boot-project/spring-boot-docs/build.gradle

@@ -293,7 +293,7 @@ task runSpringApplicationExample(type: org.springframework.boot.build.docs.Appli
 task runLoggingFormatExample(type: org.springframework.boot.build.docs.ApplicationRunner) {
 	classpath = configurations.springApplicationExample + sourceSets.main.output
 	mainClass = "org.springframework.boot.docs.features.springapplication.MyApplication"
-	args = ["--spring.main.banner-mode=off", "--server.port=0"]
+	args = ["--spring.main.banner-mode=off", "--server.port=0", "--spring.application.name=myapp"]
 	output = file("$buildDir/example-output/logging-format.txt")
 	expectedLogging = "Started MyApplication in "
 	normalizeTomcatPort()

spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/logging.adoc

@@ -31,6 +31,7 @@ The following items are output:
 * Log Level: `ERROR`, `WARN`, `INFO`, `DEBUG`, or `TRACE`.
 * Process ID.
 * A `---` separator to distinguish the start of actual log messages.
+* Application name: Enclosed in square brackets (logged by default only if configprop:spring.application.name[] is set)
 * Thread name: Enclosed in square brackets (may be truncated for console output).
 * Correlation ID: If tracing is enabled (not shown in the sample above)
 * Logger name: This is usually the source class name (often abbreviated).
@@ -39,6 +40,7 @@ The following items are output:
 NOTE: Logback does not have a `FATAL` level.
 It is mapped to `ERROR`.
 
+TIP: If you have a configprop:spring.application.name[] property but don't want it logged you can set configprop:logging.include-application-name[] to `false`.
 
 
 [[features.logging.console-output]]

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

@@ -27,6 +27,7 @@ import org.springframework.core.env.Environment;
 import org.springframework.core.env.PropertyResolver;
 import org.springframework.core.env.PropertySourcesPropertyResolver;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * Utility to set system properties that can later be used by log configuration files.
@@ -227,6 +228,7 @@ public class LoggingSystemProperties {
 
 	protected void apply(LogFile logFile, PropertyResolver resolver) {
 		String defaultCharsetName = getDefaultCharset().name();
+		setApplicationNameSystemProperty(resolver);
 		setSystemProperty(LoggingSystemProperty.PID, new ApplicationPid().toString());
 		setSystemProperty(LoggingSystemProperty.CONSOLE_CHARSET, resolver, defaultCharsetName);
 		setSystemProperty(LoggingSystemProperty.FILE_CHARSET, resolver, defaultCharsetName);
@@ -243,6 +245,16 @@ public class LoggingSystemProperties {
 		}
 	}
 
+	private void setApplicationNameSystemProperty(PropertyResolver resolver) {
+		if (resolver.getProperty("logging.include-application-name", Boolean.class, Boolean.TRUE)) {
+			String applicationName = resolver.getProperty("spring.application.name");
+			if (StringUtils.hasText(applicationName)) {
+				setSystemProperty(LoggingSystemProperty.APPLICATION_NAME.getEnvironmentVariableName(),
+						"[%s] ".formatted(applicationName));
+			}
+		}
+	}
+
 	private void setSystemProperty(LoggingSystemProperty property, PropertyResolver resolver) {
 		setSystemProperty(property, resolver, null);
 	}

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

@@ -25,6 +25,11 @@ package org.springframework.boot.logging;
  */
 public enum LoggingSystemProperty {
 
+	/**
+	 * Logging system property for the application name that should be logged.
+	 */
+	APPLICATION_NAME("LOGGED_APPLICATION_NAME"),
+
 	/**
 	 * Logging system property for the process ID.
 	 */

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

@@ -75,7 +75,7 @@ class DefaultLogbackConfiguration {
 		config.getContext()
 			.putProperty("CONSOLE_LOG_PATTERN", resolve(config, "${CONSOLE_LOG_PATTERN:-"
 					+ "%clr(%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd'T'HH:mm:ss.SSSXXX}}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) "
-					+ "%clr(${PID:- }){magenta} %clr(---){faint} %clr([%15.15t]){faint} "
+					+ "%clr(${PID:- }){magenta} %clr(---){faint} %clr(${LOGGED_APPLICATION_NAME:-}[%15.15t]){faint} "
 					+ "%clr(${LOG_CORRELATION_PATTERN:-}){faint}%clr(%-40.40logger{39}){cyan} "
 					+ "%clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"));
 		String defaultCharset = Charset.defaultCharset().name();
@@ -84,7 +84,7 @@ class DefaultLogbackConfiguration {
 		config.getContext().putProperty("CONSOLE_LOG_THRESHOLD", resolve(config, "${CONSOLE_LOG_THRESHOLD:-TRACE}"));
 		config.getContext()
 			.putProperty("FILE_LOG_PATTERN", resolve(config, "${FILE_LOG_PATTERN:-"
-					+ "%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd'T'HH:mm:ss.SSSXXX}} ${LOG_LEVEL_PATTERN:-%5p} ${PID:- } --- [%t] "
+					+ "%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd'T'HH:mm:ss.SSSXXX}} ${LOG_LEVEL_PATTERN:-%5p} ${PID:- } --- ${LOGGED_APPLICATION_NAME:-}[%t] "
 					+ "${LOG_CORRELATION_PATTERN:-}"
 					+ "%-40.40logger{39} : %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"));
 		config.getContext()

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

@@ -103,6 +103,13 @@
       "description": "Log groups to quickly change multiple loggers at the same time. For instance, `logging.group.db=org.hibernate,org.springframework.jdbc`.",
       "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener"
     },
+    {
+      "name": "logging.include-application-name",
+      "type": "java.lang.String>",
+      "description": "Whether to include the application name in the logs.",
+      "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener",
+      "defaultValue": true
+    },
     {
       "name": "logging.level",
       "type": "java.util.Map<java.lang.String,java.lang.String>",

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

@@ -4,8 +4,8 @@
 		<Property name="LOG_EXCEPTION_CONVERSION_WORD">%xwEx</Property>
 		<Property name="LOG_LEVEL_PATTERN">%5p</Property>
 		<Property name="LOG_DATEFORMAT_PATTERN">yyyy-MM-dd'T'HH:mm:ss.SSSXXX</Property>
-		<Property name="CONSOLE_LOG_PATTERN">%clr{%d{${sys:LOG_DATEFORMAT_PATTERN}}}{faint} %clr{${sys:LOG_LEVEL_PATTERN}} %clr{%pid}{magenta} %clr{---}{faint} %clr{[%15.15t]}{faint} %clr{${sys:LOG_CORRELATION_PATTERN:-}}{faint}%clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}</Property>
+		<Property name="CONSOLE_LOG_PATTERN">%clr{%d{${sys:LOG_DATEFORMAT_PATTERN}}}{faint} %clr{${sys:LOG_LEVEL_PATTERN}} %clr{%pid}{magenta} %clr{---}{faint} %clr{${sys:LOGGED_APPLICATION_NAME:-}[%15.15t]}{faint} %clr{${sys:LOG_CORRELATION_PATTERN:-}}{faint}%clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}</Property>
-		<Property name="FILE_LOG_PATTERN">%d{${sys:LOG_DATEFORMAT_PATTERN}} ${sys:LOG_LEVEL_PATTERN} %pid --- [%t] ${sys:LOG_CORRELATION_PATTERN:-}%-40.40c{1.} : %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}</Property>
+		<Property name="FILE_LOG_PATTERN">%d{${sys:LOG_DATEFORMAT_PATTERN}} ${sys:LOG_LEVEL_PATTERN} %pid --- ${sys:LOGGED_APPLICATION_NAME}[%t] ${sys:LOG_CORRELATION_PATTERN:-}%-40.40c{1.} : %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}</Property>
 	</Properties>
 	<Appenders>
 		<Console name="Console" target="SYSTEM_OUT" follow="true">

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

@@ -4,8 +4,8 @@
 		<Property name="LOG_EXCEPTION_CONVERSION_WORD">%xwEx</Property>
 		<Property name="LOG_LEVEL_PATTERN">%5p</Property>
 		<Property name="LOG_DATEFORMAT_PATTERN">yyyy-MM-dd'T'HH:mm:ss.SSSXXX</Property>
-		<Property name="CONSOLE_LOG_PATTERN">%clr{%d{${sys:LOG_DATEFORMAT_PATTERN}}}{faint} %clr{${sys:LOG_LEVEL_PATTERN}} %clr{%pid}{magenta} %clr{---}{faint} %clr{[%15.15t]}{faint} %clr{${sys:LOG_CORRELATION_PATTERN:-}}{faint}%clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}</Property>
+		<Property name="CONSOLE_LOG_PATTERN">%clr{%d{${sys:LOG_DATEFORMAT_PATTERN}}}{faint} %clr{${sys:LOG_LEVEL_PATTERN}} %clr{%pid}{magenta} %clr{---}{faint} %clr{${sys:LOGGED_APPLICATION_NAME}[%15.15t]}{faint} %clr{${sys:LOG_CORRELATION_PATTERN:-}}{faint}%clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}</Property>
-		<Property name="FILE_LOG_PATTERN">%d{${sys:LOG_DATEFORMAT_PATTERN}} ${sys:LOG_LEVEL_PATTERN} %pid --- [%t] ${sys:LOG_CORRELATION_PATTERN:-}%-40.40c{1.} : %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}</Property>
+		<Property name="FILE_LOG_PATTERN">%d{${sys:LOG_DATEFORMAT_PATTERN}} ${sys:LOG_LEVEL_PATTERN} %pid --- ${sys:LOGGED_APPLICATION_NAME}[%t] ${sys:LOG_CORRELATION_PATTERN:-}%-40.40c{1.} : %m%n${sys:LOG_EXCEPTION_CONVERSION_WORD}</Property>
 	</Properties>
 	<Appenders>
 		<Console name="Console" target="SYSTEM_OUT" follow="true">

spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/logback/defaults.xml

@@ -10,10 +10,10 @@ Default logback configuration provided for import
 	<conversionRule conversionWord="wex" converterClass="org.springframework.boot.logging.logback.WhitespaceThrowableProxyConverter" />
 	<conversionRule conversionWord="wEx" converterClass="org.springframework.boot.logging.logback.ExtendedWhitespaceThrowableProxyConverter" />
 
-	<property name="CONSOLE_LOG_PATTERN" value="${CONSOLE_LOG_PATTERN:-%clr(%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd'T'HH:mm:ss.SSSXXX}}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr([%15.15t]){faint} %clr(${LOG_CORRELATION_PATTERN:-}){faint}%clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"/>
+	<property name="CONSOLE_LOG_PATTERN" value="${CONSOLE_LOG_PATTERN:-%clr(%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd'T'HH:mm:ss.SSSXXX}}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr(${LOGGED_APPLICATION_NAME:-}[%15.15t]){faint} %clr(${LOG_CORRELATION_PATTERN:-}){faint}%clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"/>
 	<property name="CONSOLE_LOG_CHARSET" value="${CONSOLE_LOG_CHARSET:-${file.encoding:-UTF-8}}"/>
 	<property name="CONSOLE_LOG_THRESHOLD" value="${CONSOLE_LOG_THRESHOLD:-TRACE}"/>
-	<property name="FILE_LOG_PATTERN" value="${FILE_LOG_PATTERN:-%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd'T'HH:mm:ss.SSSXXX}} ${LOG_LEVEL_PATTERN:-%5p} ${PID:- } --- [%t] ${LOG_CORRELATION_PATTERN:-}%-40.40logger{39} : %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"/>
+	<property name="FILE_LOG_PATTERN" value="${FILE_LOG_PATTERN:-%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd'T'HH:mm:ss.SSSXXX}} ${LOG_LEVEL_PATTERN:-%5p} ${PID:- } --- ${LOGGED_APPLICATION_NAME:-}[%t] ${LOG_CORRELATION_PATTERN:-}%-40.40logger{39} : %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}}"/>
 	<property name="FILE_LOG_CHARSET" value="${FILE_LOG_CHARSET:-${file.encoding:-UTF-8}}"/>
 	<property name="FILE_LOG_THRESHOLD" value="${FILE_LOG_THRESHOLD:-TRACE}"/>
 

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

@@ -136,6 +136,25 @@ class LoggingSystemPropertiesTests {
 			.isEqualTo("default correlation pattern");
 	}
 
+	@Test
+	void loggedApplicationNameWhenHasApplicationName() {
+		new LoggingSystemProperties(new MockEnvironment().withProperty("spring.application.name", "test")).apply(null);
+		assertThat(getSystemProperty(LoggingSystemProperty.APPLICATION_NAME)).isEqualTo("[test] ");
+	}
+
+	@Test
+	void loggedApplicationNameWhenHasNoApplicationName() {
+		new LoggingSystemProperties(new MockEnvironment()).apply(null);
+		assertThat(getSystemProperty(LoggingSystemProperty.APPLICATION_NAME)).isNull();
+	}
+
+	@Test
+	void loggedApplicationNameWhenApplicationNameLoggingDisabled() {
+		new LoggingSystemProperties(new MockEnvironment().withProperty("spring.application.name", "test")
+			.withProperty("logging.include-application-name", "false")).apply(null);
+		assertThat(getSystemProperty(LoggingSystemProperty.APPLICATION_NAME)).isNull();
+	}
+
 	private Environment environment(String key, Object value) {
 		StandardEnvironment environment = new StandardEnvironment();
 		environment.getPropertySources().addLast(new MapPropertySource("test", Collections.singletonMap(key, value)));

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4J2LoggingSystemTests.java

@@ -564,6 +564,27 @@ class Log4J2LoggingSystemTests extends AbstractLoggingSystemTests {
 			.contains(" [0123456789012345-01234567890123456789012345678901] ");
 	}
 
+	@Test
+	void applicationNameLoggingWhenHasApplicationName(CapturedOutput output) {
+		this.environment.setProperty("spring.application.name", "myapp");
+		this.loggingSystem.setStandardConfigLocations(false);
+		this.loggingSystem.beforeInitialize();
+		this.loggingSystem.initialize(this.initializationContext, null, null);
+		this.logger.info("Hello world");
+		assertThat(getLineWithText(output, "Hello world")).contains("[myapp] ");
+	}
+
+	@Test
+	void applicationNameLoggingWhenDisabled(CapturedOutput output) {
+		this.environment.setProperty("spring.application.name", "myapp");
+		this.environment.setProperty("logging.include-application-name", "false");
+		this.loggingSystem.setStandardConfigLocations(false);
+		this.loggingSystem.beforeInitialize();
+		this.loggingSystem.initialize(this.initializationContext, null, null);
+		this.logger.info("Hello world");
+		assertThat(getLineWithText(output, "Hello world")).doesNotContain("myapp");
+	}
+
 	private String getRelativeClasspathLocation(String fileName) {
 		String defaultPath = ClassUtils.getPackageName(getClass());
 		defaultPath = defaultPath.replace('.', '/');

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

@@ -754,6 +754,23 @@ class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 			.contains(" [01234567890123456789012345678901-0123456789012345] ");
 	}
 
+	@Test
+	void applicationNameLoggingWhenHasApplicationName(CapturedOutput output) {
+		this.environment.setProperty("spring.application.name", "myapp");
+		initialize(this.initializationContext, null, null);
+		this.logger.info("Hello world");
+		assertThat(getLineWithText(output, "Hello world")).contains("[myapp] ");
+	}
+
+	@Test
+	void applicationNameLoggingWhenDisabled(CapturedOutput output) {
+		this.environment.setProperty("spring.application.name", "myapp");
+		this.environment.setProperty("logging.include-application-name", "false");
+		initialize(this.initializationContext, null, null);
+		this.logger.info("Hello world");
+		assertThat(getLineWithText(output, "Hello world")).doesNotContain("myapp");
+	}
+
 	private void initialize(LoggingInitializationContext context, String configLocation, LogFile logFile) {
 		this.loggingSystem.getSystemProperties((ConfigurableEnvironment) context.getEnvironment()).apply(logFile);
 		this.loggingSystem.beforeInitialize();

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-actuator-log4j2/src/main/resources/application.properties

@@ -1,3 +1,4 @@
+spring.application.name=sample
 spring.security.user.name=user
 spring.security.user.password=password
 management.endpoint.shutdown.enabled=true

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-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">%clr{%d{yyyy-MM-dd'T'HH:mm:ss.SSSXXX}}{faint} %clr{%5p} %clr{${sys:PID}}{magenta} %clr{---}{faint} %clr{[%15.15t]}{faint} %clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n%xwEx</Property>
+        <Property name="LOG_PATTERN">%clr{%d{yyyy-MM-dd'T'HH:mm:ss.SSSXXX}}{faint} %clr{%5p} %clr{${sys:PID}}{magenta} %clr{---}{faint} %clr{${sys:LOGGED_APPLICATION_NAME:-}[%15.15t]}{faint} %clr{%-40.40c{1.}}{cyan} %clr{:}{faint} %m%n%xwEx</Property>
     </Properties>
     <Appenders>
         <Console name="Console" target="SYSTEM_OUT" follow="true">

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-actuator/src/main/resources/application.properties

@@ -1,3 +1,4 @@
+spring.application.name=sample
 service.name=Phil
 
 spring.security.user.name=user