Add Build-Jdk-Spec to jar and war manifest when building with Gradle

This commit adds a `Build-Jdk-Spec` attribute to the manifest in a
jar or war file built with the Spring Boot Gradle plugin. This
aligns the Gradle plugin's behavior with the default Maven plugin
behavior.

This removes the need to set a `BP_JVM_VERSION` environment variable
when invoking Cloud Native Buildpacks, as the Paketo buildpacks will
honor `Build-Jdk-Spec` in a jar or war manifest to determine the
default JVM version.

Fixes gh-32829

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/plugin/JavaPluginAction.java

@@ -150,6 +150,8 @@ final class JavaPluginAction implements PluginApplicationAction {
 					.provider(() -> (String) bootJar.getManifest().getAttributes().get("Start-Class"));
 			bootJar.getMainClass().convention(resolveMainClassName.flatMap((resolver) -> manifestStartClass.isPresent()
 					? manifestStartClass : resolveMainClassName.get().readMainClassName()));
+			bootJar.getTargetJavaVersion()
+					.set(project.provider(() -> javaPluginExtension(project).getTargetCompatibility()));
 		});
 	}
 
@@ -158,8 +160,6 @@ final class JavaPluginAction implements PluginApplicationAction {
 			buildImage.setDescription("Builds an OCI image of the application using the output of the bootJar task");
 			buildImage.setGroup(BasePlugin.BUILD_GROUP);
 			buildImage.getArchiveFile().set(bootJar.get().getArchiveFile());
-			buildImage.getTargetJavaVersion()
-					.set(project.provider(() -> javaPluginExtension(project).getTargetCompatibility()));
 		});
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/plugin/WarPluginAction.java

@@ -25,6 +25,7 @@ import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.ConfigurationContainer;
 import org.gradle.api.file.FileCollection;
 import org.gradle.api.plugins.BasePlugin;
+import org.gradle.api.plugins.JavaPluginExtension;
 import org.gradle.api.plugins.WarPlugin;
 import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.SourceSet;
@@ -90,6 +91,8 @@ class WarPluginAction implements PluginApplicationAction {
 					bootWar.getMainClass()
 							.convention(resolveMainClassName.flatMap((resolver) -> manifestStartClass.isPresent()
 									? manifestStartClass : resolveMainClassName.get().readMainClassName()));
+					bootWar.getTargetJavaVersion()
+							.set(project.provider(() -> javaPluginExtension(project).getTargetCompatibility()));
 				});
 		bootWarProvider.map(War::getClasspath);
 		return bootWarProvider;
@@ -109,4 +112,8 @@ class WarPluginAction implements PluginApplicationAction {
 		this.singlePublishedArtifact.addWarCandidate(bootWar);
 	}
 
+	private JavaPluginExtension javaPluginExtension(Project project) {
+		return project.getExtensions().getByType(JavaPluginExtension.class);
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootArchive.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.gradle.tasks.bundling;
 
 import org.gradle.api.Action;
+import org.gradle.api.JavaVersion;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
 import org.gradle.api.file.FileCollection;
@@ -110,4 +111,13 @@ public interface BootArchive extends Task {
 	 */
 	void setClasspath(FileCollection classpath);
 
+	/**
+	 * Returns the target Java version of the project (e.g. as provided by the
+	 * {@code targetCompatibility} build property).
+	 * @return the target Java version
+	 */
+	@Input
+	@Optional
+	Property<JavaVersion> getTargetJavaVersion();
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootArchiveSupport.java

@@ -85,7 +85,7 @@ class BootArchiveSupport {
 	}
 
 	void configureManifest(Manifest manifest, String mainClass, String classes, String lib, String classPathIndex,
-			String layersIndex) {
+			String layersIndex, String jdkVersion) {
 		Attributes attributes = manifest.getAttributes();
 		attributes.putIfAbsent("Main-Class", this.loaderMainClass);
 		attributes.putIfAbsent("Start-Class", mainClass);
@@ -98,6 +98,7 @@ class BootArchiveSupport {
 		if (layersIndex != null) {
 			attributes.putIfAbsent("Spring-Boot-Layers-Index", layersIndex);
 		}
+		attributes.putIfAbsent("Build-Jdk-Spec", jdkVersion);
 	}
 
 	private String determineSpringBootVersion() {

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootBuildImage.java

@@ -22,7 +22,6 @@ import java.util.Map;
 
 import org.gradle.api.Action;
 import org.gradle.api.DefaultTask;
-import org.gradle.api.JavaVersion;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
 import org.gradle.api.file.RegularFileProperty;
@@ -66,8 +65,6 @@ import org.springframework.util.StringUtils;
 @DisableCachingByDefault
 public abstract class BootBuildImage extends DefaultTask {
 
-	private static final String BUILDPACK_JVM_VERSION_KEY = "BP_JVM_VERSION";
-
 	private final Property<PullPolicy> pullPolicy;
 
 	private final String projectName;
@@ -107,15 +104,6 @@ public abstract class BootBuildImage extends DefaultTask {
 	@PathSensitive(PathSensitivity.RELATIVE)
 	public abstract RegularFileProperty getArchiveFile();
 
-	/**
-	 * Returns the target Java version of the project (e.g. as provided by the
-	 * {@code targetCompatibility} build property).
-	 * @return the target Java version
-	 */
-	@Input
-	@Optional
-	public abstract Property<JavaVersion> getTargetJavaVersion();
-
 	/**
 	 * Returns the name of the image that will be built. When {@code null}, the name will
 	 * be derived from the {@link Project Project's} {@link Project#getName() name} and
@@ -340,9 +328,6 @@ public abstract class BootBuildImage extends DefaultTask {
 		if (environment != null && !environment.isEmpty()) {
 			request = request.withEnv(environment);
 		}
-		if (this.getTargetJavaVersion().isPresent() && !request.getEnv().containsKey(BUILDPACK_JVM_VERSION_KEY)) {
-			request = request.withEnv(BUILDPACK_JVM_VERSION_KEY, translateTargetJavaVersion());
-		}
 		return request;
 	}
 
@@ -401,8 +386,4 @@ public abstract class BootBuildImage extends DefaultTask {
 		return request;
 	}
 
-	private String translateTargetJavaVersion() {
-		return this.getTargetJavaVersion().get().getMajorVersion() + ".*";
-	}
-
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootJar.java

@@ -119,7 +119,8 @@ public abstract class BootJar extends Jar implements BootArchive {
 	@Override
 	public void copy() {
 		this.support.configureManifest(getManifest(), getMainClass().get(), CLASSES_DIRECTORY, LIB_DIRECTORY,
-				CLASSPATH_INDEX, (isLayeredDisabled()) ? null : LAYERS_INDEX);
+				CLASSPATH_INDEX, (isLayeredDisabled()) ? null : LAYERS_INDEX,
+				this.getTargetJavaVersion().get().getMajorVersion());
 		super.copy();
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootWar.java

@@ -94,7 +94,8 @@ public abstract class BootWar extends War implements BootArchive {
 	@Override
 	public void copy() {
 		this.support.configureManifest(getManifest(), getMainClass().get(), CLASSES_DIRECTORY, LIB_DIRECTORY,
-				CLASSPATH_INDEX, (isLayeredDisabled()) ? null : LAYERS_INDEX);
+				CLASSPATH_INDEX, (isLayeredDisabled()) ? null : LAYERS_INDEX,
+				this.getTargetJavaVersion().get().getMajorVersion());
 		super.copy();
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/AbstractBootArchiveIntegrationTests.java

@@ -478,6 +478,15 @@ abstract class AbstractBootArchiveIntegrationTests {
 		}
 	}
 
+	@TestTemplate
+	void javaVersionIsSetInManifest() throws IOException {
+		BuildResult result = this.gradleBuild.build(this.taskName);
+		assertThat(result.task(":" + this.taskName).getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		try (JarFile jarFile = new JarFile(new File(this.gradleBuild.getProjectDir(), "build/libs").listFiles()[0])) {
+			assertThat(jarFile.getManifest().getMainAttributes().getValue("Build-Jdk-Spec")).isNotEmpty();
+		}
+	}
+
 	private void copyMainClassApplication() throws IOException {
 		copyApplication("main");
 	}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootBuildImageIntegrationTests.java

@@ -73,7 +73,6 @@ class BootBuildImageIntegrationTests {
 		assertThat(result.task(":bootBuildImage").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
 		assertThat(result.getOutput()).contains("docker.io/library/" + projectName);
 		assertThat(result.getOutput()).contains("---> Test Info buildpack building");
-		assertThat(result.getOutput()).contains("env: BP_JVM_VERSION=8.*");
 		assertThat(result.getOutput()).contains("Network status: HTTP/2 200");
 		assertThat(result.getOutput()).contains("---> Test Info buildpack done");
 		removeImages(projectName);
@@ -88,7 +87,6 @@ class BootBuildImageIntegrationTests {
 		assertThat(result.task(":bootBuildImage").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
 		assertThat(result.getOutput()).contains("docker.io/library/" + projectName);
 		assertThat(result.getOutput()).contains("---> Test Info buildpack building");
-		assertThat(result.getOutput()).contains("env: BP_JVM_VERSION=8.*");
 		assertThat(result.getOutput()).contains("---> Test Info buildpack done");
 		File buildLibs = new File(this.gradleBuild.getProjectDir(), "build/libs");
 		assertThat(buildLibs.listFiles())

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootBuildImageTests.java

@@ -21,7 +21,6 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
 
-import org.gradle.api.JavaVersion;
 import org.gradle.api.Project;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -139,27 +138,6 @@ class BootBuildImageTests {
 				.hasSize(2);
 	}
 
-	@Test
-	void whenJavaVersionIsSetInEnvironmentItIsIncludedInTheRequest() {
-		this.buildImage.getEnvironment().put("BP_JVM_VERSION", "from-env");
-		this.buildImage.getTargetJavaVersion().set(JavaVersion.VERSION_1_8);
-		assertThat(this.buildImage.createRequest().getEnv()).containsEntry("BP_JVM_VERSION", "from-env").hasSize(1);
-	}
-
-	@Test
-	void whenTargetCompatibilityIsSetThenJavaVersionIsIncludedInTheRequest() {
-		this.buildImage.getTargetJavaVersion().set(JavaVersion.VERSION_1_8);
-		assertThat(this.buildImage.createRequest().getEnv()).containsEntry("BP_JVM_VERSION", "8.*").hasSize(1);
-	}
-
-	@Test
-	void whenTargetCompatibilityIsSetThenJavaVersionIsAddedToEnvironment() {
-		this.buildImage.getEnvironment().put("ALPHA", "a");
-		this.buildImage.getTargetJavaVersion().set(JavaVersion.VERSION_11);
-		assertThat(this.buildImage.createRequest().getEnv()).containsEntry("ALPHA", "a")
-				.containsEntry("BP_JVM_VERSION", "11.*").hasSize(2);
-	}
-
 	@Test
 	void whenUsingDefaultConfigurationThenRequestHasVerboseLoggingDisabled() {
 		assertThat(this.buildImage.createRequest().isVerboseLogging()).isFalse();

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootJarTests.java

@@ -22,7 +22,9 @@ import java.util.jar.JarFile;
 import java.util.zip.ZipEntry;
 
 import org.gradle.api.Action;
+import org.gradle.api.JavaVersion;
 import org.gradle.api.artifacts.Configuration;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
@@ -45,6 +47,11 @@ class BootJarTests extends AbstractBootArchiveTests<BootJar> {
 				"BOOT-INF/");
 	}
 
+	@BeforeEach
+	void setUp() {
+		this.getTask().getTargetJavaVersion().set(JavaVersion.VERSION_17);
+	}
+
 	@Test
 	void contentCanBeAddedToBootInfUsingCopySpecFromGetter() throws IOException {
 		BootJar bootJar = getTask();
@@ -194,6 +201,14 @@ class BootJarTests extends AbstractBootArchiveTests<BootJar> {
 		}
 	}
 
+	@Test
+	void javaVersionIsWrittenToManifest() throws IOException {
+		try (JarFile jarFile = new JarFile(createPopulatedJar())) {
+			assertThat(jarFile.getManifest().getMainAttributes().getValue("Build-Jdk-Spec"))
+					.isEqualTo(JavaVersion.VERSION_17.getMajorVersion());
+		}
+	}
+
 	@Override
 	void applyLayered(Action<LayeredSpec> action) {
 		getTask().layered(action);

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootWarTests.java

@@ -21,7 +21,9 @@ import java.io.IOException;
 import java.util.jar.JarFile;
 
 import org.gradle.api.Action;
+import org.gradle.api.JavaVersion;
 import org.gradle.api.artifacts.Configuration;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
@@ -42,6 +44,11 @@ class BootWarTests extends AbstractBootArchiveTests<BootWar> {
 				"WEB-INF/");
 	}
 
+	@BeforeEach
+	void setUp() {
+		this.getTask().getTargetJavaVersion().set(JavaVersion.VERSION_17);
+	}
+
 	@Test
 	void providedClasspathJarsArePackagedInWebInfLibProvided() throws IOException {
 		getTask().getMainClass().set("com.example.Main");
@@ -137,6 +144,14 @@ class BootWarTests extends AbstractBootArchiveTests<BootWar> {
 		}
 	}
 
+	@Test
+	void javaVersionIsWrittenToManifest() throws IOException {
+		try (JarFile jarFile = new JarFile(createPopulatedJar())) {
+			assertThat(jarFile.getManifest().getMainAttributes().getValue("Build-Jdk-Spec"))
+					.isEqualTo(JavaVersion.VERSION_17.getMajorVersion());
+		}
+	}
+
 	@Override
 	protected void executeTask() {
 		getTask().copy();

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/BuildImageTests.java

@@ -58,8 +58,8 @@ class BuildImageTests extends AbstractArchiveIntegrationTests {
 					assertThat(original).doesNotExist();
 					assertThat(buildLog(project)).contains("Building image")
 							.contains("docker.io/library/build-image:0.0.1.BUILD-SNAPSHOT")
-							.contains("---> Test Info buildpack building").contains("env: BP_JVM_VERSION=8.*")
-							.contains("---> Test Info buildpack done").contains("Successfully built image");
+							.contains("---> Test Info buildpack building").contains("---> Test Info buildpack done")
+							.contains("Successfully built image");
 					removeImage("build-image", "0.0.1.BUILD-SNAPSHOT");
 				});
 	}
@@ -75,8 +75,8 @@ class BuildImageTests extends AbstractArchiveIntegrationTests {
 					assertThat(classifier).doesNotExist();
 					assertThat(buildLog(project)).contains("Building image")
 							.contains("docker.io/library/build-image-classifier:0.0.1.BUILD-SNAPSHOT")
-							.contains("---> Test Info buildpack building").contains("env: BP_JVM_VERSION=8.*")
-							.contains("---> Test Info buildpack done").contains("Successfully built image");
+							.contains("---> Test Info buildpack building").contains("---> Test Info buildpack done")
+							.contains("Successfully built image");
 					removeImage("build-image-classifier", "0.0.1.BUILD-SNAPSHOT");
 				});
 	}

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/BuildImageMojo.java

@@ -68,8 +68,6 @@ import org.springframework.util.StringUtils;
 @Execute(phase = LifecyclePhase.PACKAGE)
 public class BuildImageMojo extends AbstractPackagerMojo {
 
-	private static final String BUILDPACK_JVM_VERSION_KEY = "BP_JVM_VERSION";
-
 	static {
 		System.setProperty("org.slf4j.simpleLogger.log.org.apache.http.wire", "ERROR");
 	}
@@ -293,22 +291,10 @@ public class BuildImageMojo extends AbstractPackagerMojo {
 	}
 
 	private BuildRequest customize(BuildRequest request) {
-		request = customizeEnvironment(request);
 		request = customizeCreator(request);
 		return request;
 	}
 
-	private BuildRequest customizeEnvironment(BuildRequest request) {
-		if (!request.getEnv().containsKey(BUILDPACK_JVM_VERSION_KEY)) {
-			JavaCompilerPluginConfiguration compilerConfiguration = new JavaCompilerPluginConfiguration(this.project);
-			String targetJavaVersion = compilerConfiguration.getTargetMajorVersion();
-			if (StringUtils.hasText(targetJavaVersion)) {
-				return request.withEnv(BUILDPACK_JVM_VERSION_KEY, targetJavaVersion + ".*");
-			}
-		}
-		return request;
-	}
-
 	private BuildRequest customizeCreator(BuildRequest request) {
 		String springBootVersion = VersionExtractor.forClass(BuildImageMojo.class);
 		if (StringUtils.hasText(springBootVersion)) {

spring-boot-system-tests/spring-boot-image-tests/src/systemTest/resources/org/springframework/boot/image/paketo/PaketoBuilderTests-bootDistZipJarApp.gradle

@@ -38,4 +38,5 @@ application {
 
 bootBuildImage {
 	archiveFile = bootDistZip.archiveFile
+	environment = ['BP_JVM_VERSION': project.targetCompatibility.getMajorVersion()]
 }

spring-boot-system-tests/spring-boot-image-tests/src/systemTest/resources/org/springframework/boot/image/paketo/PaketoBuilderTests-plainDistZipJarApp.gradle

@@ -38,4 +38,5 @@ application {
 
 bootBuildImage {
 	archiveFile = distZip.archiveFile
+	environment = ['BP_JVM_VERSION': project.targetCompatibility.getMajorVersion()]
 }

spring-boot-system-tests/spring-boot-image-tests/src/systemTest/resources/org/springframework/boot/image/paketo/PaketoBuilderTests-plainWarApp.gradle

@@ -31,5 +31,5 @@ war {
 
 bootBuildImage {
 	archiveFile = war.archiveFile
-	environment = ['BP_TOMCAT_VERSION': '10.*']
+	environment = ['BP_JVM_VERSION': project.targetCompatibility.getMajorVersion(), 'BP_TOMCAT_VERSION': '10.*']
 }

spring-boot-tests/spring-boot-integration-tests/spring-boot-server-tests/spring-boot-server-tests-app/build.gradle

@@ -72,6 +72,7 @@ def boolean isWindows() {
 		task.mainClass = "com.example.ResourceHandlingApplication"
 		task.classpath = sourceSets.main.runtimeClasspath.plus(configurations.getByName(container))
 		task.classifier = container
+		task.targetJavaVersion = project.getTargetCompatibility()
 	}
 	tasks.register("${container}BootJar", BootJar, configurer)
 	tasks.register("${container}BootWar", BootWar, configurer)