Automatically disable banner when using structured logging

Closes gh-41659

Author: mhalbritter

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/ApplicationProperties.java

@@ -20,6 +20,8 @@
 import java.util.Set;
 
 import org.springframework.boot.Banner.Mode;
+import org.springframework.boot.logging.LoggingSystemProperty;
+import org.springframework.core.env.Environment;
 
 /**
  * Spring application properties.
@@ -43,7 +45,7 @@ class ApplicationProperties {
 	/**
 	 * Mode used to display the banner when the application runs.
 	 */
-	private Banner.Mode bannerMode = Banner.Mode.CONSOLE;
+	private Banner.Mode bannerMode;
 
 	/**
 	 * Whether to keep the application alive even if there are no more non-daemon threads.
@@ -93,8 +95,13 @@ void setAllowCircularReferences(boolean allowCircularReferences) {
 		this.allowCircularReferences = allowCircularReferences;
 	}
 
-	Mode getBannerMode() {
-		return this.bannerMode;
+	Mode getBannerMode(Environment environment) {
+		if (this.bannerMode != null) {
+			return this.bannerMode;
+		}
+		boolean structuredLoggingEnabled = environment
+			.containsProperty(LoggingSystemProperty.CONSOLE_STRUCTURED_FORMAT.getApplicationPropertyName());
+		return (structuredLoggingEnabled) ? Mode.OFF : Banner.Mode.CONSOLE;
 	}
 
 	void setBannerMode(Mode bannerMode) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -555,13 +555,13 @@ protected void bindToSpringApplication(ConfigurableEnvironment environment) {
 	}
 
 	private Banner printBanner(ConfigurableEnvironment environment) {
-		if (this.properties.getBannerMode() == Banner.Mode.OFF) {
+		if (this.properties.getBannerMode(environment) == Banner.Mode.OFF) {
 			return null;
 		}
 		ResourceLoader resourceLoader = (this.resourceLoader != null) ? this.resourceLoader
 				: new DefaultResourceLoader(null);
 		SpringApplicationBannerPrinter bannerPrinter = new SpringApplicationBannerPrinter(resourceLoader, this.banner);
-		if (this.properties.getBannerMode() == Mode.LOG) {
+		if (this.properties.getBannerMode(environment) == Mode.LOG) {
 			return bannerPrinter.print(environment, this.mainApplicationClass, logger);
 		}
 		return bannerPrinter.print(environment, this.mainApplicationClass, System.out);

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

@@ -140,7 +140,13 @@ public String getEnvironmentVariableName() {
 		return this.environmentVariableName;
 	}
 
-	String getApplicationPropertyName() {
+	/**
+	 * Return the name of the application property name that can be used to set this
+	 * property.
+	 * @return the application property name
+	 * @since 3.4.0
+	 */
+	public String getApplicationPropertyName() {
 		return this.applicationPropertyName;
 	}
 

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

@@ -426,8 +426,7 @@
       "name": "spring.main.banner-mode",
       "type": "org.springframework.boot.Banner$Mode",
       "sourceType": "org.springframework.boot.SpringApplication",
-      "description": "Mode used to display the banner when the application runs.",
-      "defaultValue": "console"
+      "description": "Mode used to display the banner when the application runs. Defaults to 'off' if structured logging is enabled or to 'console' otherwise"
     },
     {
       "name": "spring.main.cloud-platform",

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/ApplicationPropertiesTests.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2024 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;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.Banner.Mode;
+import org.springframework.mock.env.MockEnvironment;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link ApplicationProperties}.
+ *
+ * @author Moritz Halbritter
+ */
+class ApplicationPropertiesTests {
+
+	@Test
+	void bannerModeShouldBeConsoleIfStructuredLoggingIsNotEnabled() {
+		ApplicationProperties properties = new ApplicationProperties();
+		assertThat(properties.getBannerMode(new MockEnvironment())).isEqualTo(Mode.CONSOLE);
+	}
+
+	@Test
+	void bannerModeShouldBeOffIfStructuredLoggingIsEnabled() {
+		ApplicationProperties properties = new ApplicationProperties();
+		MockEnvironment environment = new MockEnvironment();
+		environment.setProperty("logging.structured.format.console", "ecs");
+		assertThat(properties.getBannerMode(environment)).isEqualTo(Mode.OFF);
+	}
+
+}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java

@@ -1647,7 +1647,7 @@ BeanDefinitionLoader getLoader() {
 		}
 
 		Banner.Mode getBannerMode() {
-			return this.properties.getBannerMode();
+			return this.properties.getBannerMode(new MockEnvironment());
 		}
 
 	}

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

@@ -1,4 +1,3 @@
-spring.main.banner-mode=off
 logging.structured.format.console=ecs
 #---
 spring.config.activate.on-profile=custom

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-structure-logging-log4j2/src/test/java/smoketest/structuredlogging/log4j2/SampleLog4j2StructuredLoggingApplicationTests.java

@@ -43,6 +43,12 @@ void reset() {
 		}
 	}
 
+	@Test
+	void shouldNotLogBanner(CapturedOutput output) {
+		SampleLog4j2StructuredLoggingApplication.main(new String[0]);
+		assertThat(output).doesNotContain(" :: Spring Boot :: ");
+	}
+
 	@Test
 	void json(CapturedOutput output) {
 		SampleLog4j2StructuredLoggingApplication.main(new String[0]);

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

@@ -1,4 +1,3 @@
-spring.main.banner-mode=off
 logging.structured.format.console=ecs
 #---
 spring.config.activate.on-profile=custom

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-structure-logging/src/test/java/smoketest/structuredlogging/SampleStructuredLoggingApplicationTests.java

@@ -43,6 +43,12 @@ void reset() {
 		}
 	}
 
+	@Test
+	void shouldNotLogBanner(CapturedOutput output) {
+		SampleStructuredLoggingApplication.main(new String[0]);
+		assertThat(output).doesNotContain(" :: Spring Boot :: ");
+	}
+
 	@Test
 	void json(CapturedOutput output) {
 		SampleStructuredLoggingApplication.main(new String[0]);