Make bootBuildImage produce native image when NBT plugin is applied

Closes gh-32768

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/asciidoc/packaging-oci-image.adoc

@@ -105,7 +105,7 @@ The following table summarizes the available properties and their default values
 | `builder`
 | `--builder`
 | Name of the Builder image to use.
-| `paketobuildpacks/builder:base`
+| `paketobuildpacks/builder:base` or `paketobuildpacks/builder:tiny` when {nbt-gradle-plugin}[GraalVM Native Image plugin] is applied.
 
 | `runImage`
 | `--runImage`
@@ -126,7 +126,7 @@ Acceptable values are `ALWAYS`, `NEVER`, and `IF_NOT_PRESENT`.
 | `environment`
 |
 | Environment variables that should be passed to the builder.
-|
+| Empty or `['BP_NATIVE_IMAGE': 'true']` when {nbt-gradle-plugin}[GraalVM Native Image plugin] is applied.
 
 | `buildpacks`
 |

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/asciidoc/reacting.adoc

@@ -79,5 +79,6 @@ When the {nbt-gradle-plugin}[GraalVM Native Image plugin] is applied to a projec
 . Adds the output of the `aotTest` source set to the classpath of the `test` GraalVM native binary.
 . Configures the GraalVM extension to disable Toolchain detection.
 . Configures the `bootJar` task to include the reachability metadata produced by the `collectReachabilityMetadata` task in its jar.
+. Configures the `bootBuildImage` task to use `paketobuildpacks/builder:tiny` as its builder and to set `BP_NATIVE_IMAGE` to `true` in its environment.
 
 

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

@@ -28,6 +28,7 @@ import org.gradle.api.plugins.JavaPluginExtension;
 import org.gradle.api.tasks.SourceSetContainer;
 import org.gradle.api.tasks.SourceSetOutput;
 
+import org.springframework.boot.gradle.tasks.bundling.BootBuildImage;
 import org.springframework.boot.gradle.tasks.bundling.BootJar;
 
 /**
@@ -58,6 +59,7 @@ class NativeImagePluginAction implements PluginApplicationAction {
 					SpringBootAotPlugin.AOT_TEST_SOURCE_SET_NAME);
 			configureGraalVmReachabilityExtension(graalVmExtension);
 			copyReachabilityMetadataToBootJar(project);
+			configureBootBuildImageToProduceANativeImage(project);
 		});
 	}
 
@@ -84,4 +86,12 @@ class NativeImagePluginAction implements PluginApplicationAction {
 				.configure((bootJar) -> bootJar.from(project.getTasks().named("collectReachabilityMetadata")));
 	}
 
+	private void configureBootBuildImageToProduceANativeImage(Project project) {
+		project.getTasks().named(SpringBootPlugin.BOOT_BUILD_IMAGE_TASK_NAME, BootBuildImage.class)
+				.configure((bootBuildImage) -> {
+					bootBuildImage.setBuilder("paketobuildpacks/builder:tiny");
+					bootBuildImage.environment("BP_NATIVE_IMAGE", "true");
+				});
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/plugin/NativeImagePluginActionIntegrationTests.java

@@ -87,6 +87,13 @@ class NativeImagePluginActionIntegrationTests {
 				"META-INF/native-image/org.jline/jline/3.21.0/resource-config.json");
 	}
 
+	@TestTemplate
+	void bootBuildImageIsConfiguredToBuildANativeImage() {
+		writeDummySpringApplicationAotProcessorMainClass();
+		BuildResult result = this.gradleBuild.build("bootBuildImageConfiguration");
+		assertThat(result.getOutput()).contains("paketobuildpacks/builder:tiny").contains("BP_NATIVE_IMAGE = true");
+	}
+
 	private void writeDummySpringApplicationAotProcessorMainClass() {
 		File examplePackage = new File(this.gradleBuild.getProjectDir(), "src/main/java/org/springframework/boot");
 		examplePackage.mkdirs();

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/plugin/NativeImagePluginActionIntegrationTests-bootBuildImageIsConfiguredToBuildANativeImage.gradle

@@ -0,0 +1,13 @@
+plugins {
+	id 'org.springframework.boot' version '{version}'
+	id 'java'
+}
+
+apply plugin: 'org.graalvm.buildtools.native'
+
+task('bootBuildImageConfiguration') {
+	doFirst {
+		println "builder = ${tasks.getByName('bootBuildImage').builder}"
+		println "BP_NATIVE_IMAGE = ${tasks.getByName('bootBuildImage').environment['BP_NATIVE_IMAGE']}"
+	}
+}