Add buildpack option for image building

This commit adds configuration to the Maven and Gradle plugins to
allow a list of buildpacks to be provided to the image building
goal and task.

Fixes gh-21722

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

@@ -130,6 +130,18 @@ Acceptable values are `ALWAYS`, `NEVER`, and `IF_NOT_PRESENT`.
 | Environment variables that should be passed to the builder.
 |
 
+| `buildpacks`
+|
+a|Buildpacks that the builder should use when building the image.
+Only the specified buildpacks will be used, overriding the default buildpacks included in the builder.
+Buildpack references must be in one of the following forms:
+
+* Buildpack in the builder - [urn:cnb:builder:]<buildpack id>[@<version>]
+* Buildpack in a directory on the file system - [file://]<path>
+* Buildpack in a gzipped tar (.tgz) file on the file system - [file://]<path>/<file name>
+* Buildpack in an OCI image - [docker://]<host>/<repo>[:<tag>][@<digest>]
+| None, indicating the builder should use the buildpacks included in it.
+
 | `cleanCache`
 | `--cleanCache`
 | Whether to clean the cache before building.
@@ -249,6 +261,58 @@ The image name can be specified on the command line as well, as shown in this ex
 	$ gradle bootBuildImage --imageName=example.com/library/my-app:v1
 ----
 
+
+
+[[build-image-example-buildpacks]]
+==== Buildpacks
+By default, the builder will use buildpacks included in the builder image and apply them in a pre-defined order.
+An alternative set of buildpacks can be provided to apply buildpacks that are not included in the builder, or to change the order of included buildpacks.
+When one or more buildpacks are provided, only the specified buildpacks will be applied.
+
+The following example instructs the builder to use a custom buildpack packaged in a `.tgz` file, followed by a buildpack included in the builder.
+
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
+----
+include::../gradle/packaging/boot-build-image-buildpacks.gradle[tags=buildpacks]
+----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/packaging/boot-build-image-buildpacks.gradle.kts[tags=buildpacks]
+----
+
+Buildpacks can be specified in any of the forms shown below.
+
+A buildpack located in a CNB Builder (version may be omitted if there is only one buildpack in the builder matching the `buildpack-id`):
+
+* `urn:cnb:builder:buildpack-id`
+* `urn:cnb:builder:buildpack-id@0.0.1`
+* `buildpack-id`
+* `buildpack-id@0.0.1`
+
+A path to a directory containing buildpack content (not supported on Windows):
+
+* `\file:///path/to/buildpack/`
+* `/path/to/buildpack/`BootBuildImageIntegrationTests
+
+A path to a gzipped tar file containing buildpack content:
+
+* `\file:///path/to/buildpack.tgz`
+* `/path/to/buildpack.tgz`
+
+An OCI image containing a https://buildpacks.io/docs/buildpack-author-guide/package-a-buildpack/[packaged buildpack]:
+
+* `docker://example/buildpack`
+* `docker:///example/buildpack:latest`
+* `docker:///example/buildpack@sha256:45b23dee08...`
+* `example/buildpack`
+* `example/buildpack:latest`
+* `example/buildpack@sha256:45b23dee08...`
+
+
+
 [[build-image-example-publish]]
 ==== Image Publishing
 The generated image can be published to a Docker registry by enabling a `publish` option and configuring authentication for the registry using `docker.publishRegistry` properties.
@@ -272,6 +336,8 @@ The publish option can be specified on the command line as well, as shown in thi
 	$ gradle bootBuildImage --imageName=docker.example.com/library/my-app:v1 --publishImage
 ----
 
+
+
 [[build-image-example-docker]]
 ==== Docker Configuration
 If you need the plugin to communicate with the Docker daemon using a remote connection instead of the default local connection, the connection details can be provided using `docker` properties as shown in the following example:

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-buildpacks.gradle

@@ -0,0 +1,16 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{gradle-project-version}'
+}
+
+// tag::buildpacks[]
+bootBuildImage {
+	buildpacks = ["file:///path/to/example-buildpack.tgz", "urn:cnb:builder:paketo-buildpacks/java"]
+}
+// end::buildpacks[]
+
+task bootBuildImageBuildpacks {
+	doFirst {
+		bootBuildImage.buildpacks.each { reference -> println "$reference" }
+	}
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-buildpacks.gradle.kts

@@ -0,0 +1,20 @@
+import org.springframework.boot.gradle.tasks.bundling.BootBuildImage
+
+plugins {
+	java
+	id("org.springframework.boot") version "{gradle-project-version}"
+}
+
+// tag::buildpacks[]
+tasks.getByName<BootBuildImage>("bootBuildImage") {
+    buildpacks = listOf("file:///path/to/example-buildpack.tgz", "urn:cnb:builder:paketo-buildpacks/java")
+}
+// end::buildpacks[]
+
+tasks.register("bootBuildImageBuildpacks") {
+    doFirst {
+        for((reference) in tasks.getByName<BootBuildImage>("bootBuildImage").buildpacks) {
+            print(reference)
+        }
+    }
+}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -18,7 +18,9 @@ package org.springframework.boot.gradle.tasks.bundling;
 
 import java.io.IOException;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 import groovy.lang.Closure;
 import org.gradle.api.Action;
@@ -28,6 +30,7 @@ import org.gradle.api.JavaVersion;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
 import org.gradle.api.file.RegularFileProperty;
+import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Property;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.Nested;
@@ -38,6 +41,7 @@ import org.gradle.util.ConfigureUtil;
 
 import org.springframework.boot.buildpack.platform.build.BuildRequest;
 import org.springframework.boot.buildpack.platform.build.Builder;
+import org.springframework.boot.buildpack.platform.build.BuildpackReference;
 import org.springframework.boot.buildpack.platform.build.Creator;
 import org.springframework.boot.buildpack.platform.build.PullPolicy;
 import org.springframework.boot.buildpack.platform.docker.transport.DockerEngineException;
@@ -83,6 +87,8 @@ public class BootBuildImage extends DefaultTask {
 
 	private boolean publish;
 
+	private ListProperty<String> buildpacks;
+
 	private DockerSpec docker = new DockerSpec();
 
 	public BootBuildImage() {
@@ -92,6 +98,7 @@ public class BootBuildImage extends DefaultTask {
 		this.projectVersion = getProject().getObjects().property(String.class);
 		Project project = getProject();
 		this.projectVersion.set(getProject().provider(() -> project.getVersion().toString()));
+		this.buildpacks = getProject().getObjects().listProperty(String.class);
 	}
 
 	/**
@@ -283,6 +290,40 @@ public class BootBuildImage extends DefaultTask {
 		this.publish = publish;
 	}
 
+	/**
+	 * Returns the buildpacks that will be used when building the image.
+	 * @return the buildpacks
+	 */
+	@Input
+	@Optional
+	public List<String> getBuildpacks() {
+		return this.buildpacks.getOrNull();
+	}
+
+	/**
+	 * Sets the buildpacks that will be used when building the image.
+	 * @param buildpacks the buildpacks
+	 */
+	public void setBuildpacks(List<String> buildpacks) {
+		this.buildpacks.set(buildpacks);
+	}
+
+	/**
+	 * Add an entry to the buildpacks that will be used when building the image.
+	 * @param buildpack the buildpack reference
+	 */
+	public void buildpack(String buildpack) {
+		this.buildpacks.add(buildpack);
+	}
+
+	/**
+	 * Adds entries to the environment that will be used when building the image.
+	 * @param buildpacks the buildpack references
+	 */
+	public void buildpacks(List<String> buildpacks) {
+		this.buildpacks.addAll(buildpacks);
+	}
+
 	/**
 	 * Returns the Docker configuration the builder will use.
 	 * @return docker configuration.
@@ -316,8 +357,8 @@ public class BootBuildImage extends DefaultTask {
 		if (!this.jar.isPresent()) {
 			throw new GradleException("Executable jar file required for building image");
 		}
-		Builder builder = new Builder(this.docker.asDockerConfiguration());
 		BuildRequest request = createRequest();
+		Builder builder = new Builder(this.docker.asDockerConfiguration());
 		builder.build(request);
 	}
 
@@ -346,6 +387,7 @@ public class BootBuildImage extends DefaultTask {
 		request = request.withVerboseLogging(this.verboseLogging);
 		request = customizePullPolicy(request);
 		request = customizePublish(request);
+		request = customizeBuildpacks(request);
 		return request;
 	}
 
@@ -398,6 +440,14 @@ public class BootBuildImage extends DefaultTask {
 		return request;
 	}
 
+	private BuildRequest customizeBuildpacks(BuildRequest request) {
+		List<String> buildpacks = this.buildpacks.getOrNull();
+		if (buildpacks != null && !buildpacks.isEmpty()) {
+			return request.withBuildpacks(buildpacks.stream().map(BuildpackReference::of).collect(Collectors.toList()));
+		}
+		return request;
+	}
+
 	private String translateTargetJavaVersion() {
 		return this.targetJavaVersion.get().getMajorVersion() + ".*";
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -23,11 +23,21 @@ import java.io.PrintWriter;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.nio.file.attribute.FileAttribute;
+import java.nio.file.attribute.PosixFilePermission;
+import java.nio.file.attribute.PosixFilePermissions;
 import java.util.Random;
+import java.util.Set;
 
+import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
+import org.apache.commons.compress.archivers.tar.TarArchiveOutputStream;
+import org.apache.commons.compress.compressors.gzip.GzipCompressorOutputStream;
+import org.apache.commons.compress.utils.IOUtils;
 import org.gradle.testkit.runner.BuildResult;
 import org.gradle.testkit.runner.TaskOutcome;
 import org.junit.jupiter.api.TestTemplate;
+import org.junit.jupiter.api.condition.DisabledOnOs;
+import org.junit.jupiter.api.condition.OS;
 import org.testcontainers.containers.GenericContainer;
 import org.testcontainers.containers.wait.strategy.Wait;
 
@@ -145,7 +155,72 @@ class BootBuildImageIntegrationTests {
 	}
 
 	@TestTemplate
-	void failsWithLaunchScript() {
+	void buildsImageWithBuildpackFromBuilder() throws IOException {
+		writeMainClass();
+		writeLongNameResource();
+		BuildResult result = this.gradleBuild.build("bootBuildImage", "--pullPolicy=IF_NOT_PRESENT");
+		String projectName = this.gradleBuild.getProjectDir().getName();
+		assertThat(result.task(":bootBuildImage").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.getOutput()).contains("docker.io/library/" + projectName);
+		ImageReference imageReference = ImageReference.of(ImageName.of(projectName));
+		try (GenericContainer<?> container = new GenericContainer<>(imageReference.toString())) {
+			container.waitingFor(Wait.forLogMessage("Launched\\n", 1)).start();
+		}
+		finally {
+			new DockerApi().image().remove(imageReference, false);
+		}
+	}
+
+	@TestTemplate
+	@DisabledOnOs(OS.WINDOWS)
+	void buildsImageWithBuildpackFromDirectory() throws IOException {
+		writeMainClass();
+		writeLongNameResource();
+		writeBuildpackContent();
+		BuildResult result = this.gradleBuild.build("bootBuildImage", "--pullPolicy=IF_NOT_PRESENT");
+		String projectName = this.gradleBuild.getProjectDir().getName();
+		ImageReference imageReference = ImageReference.of(ImageName.of(projectName));
+		assertThat(result.task(":bootBuildImage").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.getOutput()).contains("docker.io/library/" + projectName);
+		assertThat(result.getOutput()).contains("---> Hello World buildpack");
+		new DockerApi().image().remove(imageReference, false);
+	}
+
+	@TestTemplate
+	@DisabledOnOs(OS.WINDOWS)
+	void buildsImageWithBuildpackFromTarGzip() throws IOException {
+		writeMainClass();
+		writeLongNameResource();
+		writeBuildpackContent();
+		tarGzipBuildpackContent();
+		BuildResult result = this.gradleBuild.build("bootBuildImage", "--pullPolicy=IF_NOT_PRESENT");
+		String projectName = this.gradleBuild.getProjectDir().getName();
+		ImageReference imageReference = ImageReference.of(ImageName.of(projectName));
+		assertThat(result.task(":bootBuildImage").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.getOutput()).contains("docker.io/library/" + projectName);
+		assertThat(result.getOutput()).contains("---> Hello World buildpack");
+		new DockerApi().image().remove(imageReference, false);
+	}
+
+	@TestTemplate
+	void buildsImageWithBuildpackFromImage() throws IOException {
+		writeMainClass();
+		writeLongNameResource();
+		BuildResult result = this.gradleBuild.build("bootBuildImage", "--pullPolicy=IF_NOT_PRESENT");
+		String projectName = this.gradleBuild.getProjectDir().getName();
+		assertThat(result.task(":bootBuildImage").getOutcome()).isEqualTo(TaskOutcome.SUCCESS);
+		assertThat(result.getOutput()).contains("docker.io/library/" + projectName);
+		ImageReference imageReference = ImageReference.of(ImageName.of(projectName));
+		try (GenericContainer<?> container = new GenericContainer<>(imageReference.toString())) {
+			container.waitingFor(Wait.forLogMessage("Launched\\n", 1)).start();
+		}
+		finally {
+			new DockerApi().image().remove(imageReference, false);
+		}
+	}
+
+	@TestTemplate
+	void failsWithLaunchScript() throws IOException {
 		writeMainClass();
 		writeLongNameResource();
 		BuildResult result = this.gradleBuild.buildAndFail("bootBuildImage");
@@ -154,7 +229,7 @@ class BootBuildImageIntegrationTests {
 	}
 
 	@TestTemplate
-	void failsWithBuilderError() {
+	void failsWithBuilderError() throws IOException {
 		writeMainClass();
 		writeLongNameResource();
 		BuildResult result = this.gradleBuild.buildAndFail("bootBuildImage", "--pullPolicy=IF_NOT_PRESENT");
@@ -163,7 +238,7 @@ class BootBuildImageIntegrationTests {
 	}
 
 	@TestTemplate
-	void failsWithInvalidImageName() {
+	void failsWithInvalidImageName() throws IOException {
 		writeMainClass();
 		writeLongNameResource();
 		BuildResult result = this.gradleBuild.buildAndFail("bootBuildImage", "--imageName=example/Invalid-Image-Name");
@@ -173,7 +248,7 @@ class BootBuildImageIntegrationTests {
 	}
 
 	@TestTemplate
-	void failsWithPublishMissingPublishRegistry() {
+	void failsWithPublishMissingPublishRegistry() throws IOException {
 		writeMainClass();
 		writeLongNameResource();
 		BuildResult result = this.gradleBuild.buildAndFail("bootBuildImage", "--publishImage");
@@ -182,7 +257,7 @@ class BootBuildImageIntegrationTests {
 	}
 
 	@TestTemplate
-	void failsWithWarPackaging() {
+	void failsWithWarPackaging() throws IOException {
 		writeMainClass();
 		writeLongNameResource();
 		BuildResult result = this.gradleBuild.buildAndFail("bootBuildImage", "-PapplyWarPlugin");
@@ -190,6 +265,15 @@ class BootBuildImageIntegrationTests {
 		assertThat(result.getOutput()).contains("Executable jar file required for building image");
 	}
 
+	@TestTemplate
+	void failsWithBuildpackNotInBuilder() throws IOException {
+		writeMainClass();
+		writeLongNameResource();
+		BuildResult result = this.gradleBuild.buildAndFail("bootBuildImage", "--pullPolicy=IF_NOT_PRESENT");
+		assertThat(result.task(":bootBuildImage").getOutcome()).isEqualTo(TaskOutcome.FAILED);
+		assertThat(result.getOutput()).contains("'urn:cnb:builder:example/does-not-exist:0.0.1' not found in builder");
+	}
+
 	@TestTemplate
 	void buildsImageWithWarPackagingAndJarConfiguration() throws IOException {
 		writeMainClass();
@@ -210,7 +294,7 @@ class BootBuildImageIntegrationTests {
 		}
 	}
 
-	private void writeMainClass() {
+	private void writeMainClass() throws IOException {
 		File examplePackage = new File(this.gradleBuild.getProjectDir(), "src/main/java/example");
 		examplePackage.mkdirs();
 		File main = new File(examplePackage, "Main.java");
@@ -230,23 +314,70 @@ class BootBuildImageIntegrationTests {
 			writer.println();
 			writer.println("}");
 		}
-		catch (IOException ex) {
-			throw new RuntimeException(ex);
+	}
+
+	private void writeLongNameResource() throws IOException {
+		StringBuilder name = new StringBuilder();
+		new Random().ints('a', 'z' + 1).limit(128).forEach((i) -> name.append((char) i));
+		Path path = this.gradleBuild.getProjectDir().toPath()
+				.resolve(Paths.get("src", "main", "resources", name.toString()));
+		Files.createDirectories(path.getParent());
+		Files.createFile(path);
+	}
+
+	private void writeBuildpackContent() throws IOException {
+		File buildpackDir = new File(this.gradleBuild.getProjectDir(), "buildpack/hello-world");
+		buildpackDir.mkdirs();
+		File descriptor = new File(buildpackDir, "buildpack.toml");
+		try (PrintWriter writer = new PrintWriter(new FileWriter(descriptor))) {
+			writer.println("api = \"0.2\"");
+			writer.println("[buildpack]");
+			writer.println("id = \"example/hello-world\"");
+			writer.println("version = \"0.0.1\"");
+			writer.println("name = \"Hello World Buildpack\"");
+			writer.println("homepage = \"https://github.com/buildpacks/samples/tree/main/buildpacks/hello-world\"");
+			writer.println("[[stacks]]\n");
+			writer.println("id = \"io.buildpacks.stacks.bionic\"");
+		}
+		File binDir = new File(buildpackDir, "bin");
+		binDir.mkdirs();
+		FileAttribute<Set<PosixFilePermission>> attribute = PosixFilePermissions
+				.asFileAttribute(PosixFilePermissions.fromString("rwxrwxrwx"));
+		File detect = Files.createFile(Paths.get(binDir.getAbsolutePath(), "detect"), attribute).toFile();
+		try (PrintWriter writer = new PrintWriter(new FileWriter(detect))) {
+			writer.println("#!/usr/bin/env bash");
+			writer.println("set -eo pipefail");
+			writer.println("exit 0");
+		}
+		File build = Files.createFile(Paths.get(binDir.getAbsolutePath(), "build"), attribute).toFile();
+		try (PrintWriter writer = new PrintWriter(new FileWriter(build))) {
+			writer.println("#!/usr/bin/env bash");
+			writer.println("set -eo pipefail");
+			writer.println("echo \"---> Hello World buildpack\"");
+			writer.println("echo \"---> done\"");
+			writer.println("exit 0");
 		}
 	}
 
-	private void writeLongNameResource() {
-		StringBuilder name = new StringBuilder();
-		new Random().ints('a', 'z' + 1).limit(128).forEach((i) -> name.append((char) i));
-		try {
-			Path path = this.gradleBuild.getProjectDir().toPath()
-					.resolve(Paths.get("src", "main", "resources", name.toString()));
-			Files.createDirectories(path.getParent());
-			Files.createFile(path);
-		}
-		catch (IOException ex) {
-			throw new RuntimeException(ex);
+	private void tarGzipBuildpackContent() throws IOException {
+		Path tarGzipPath = Paths.get(this.gradleBuild.getProjectDir().getAbsolutePath(), "hello-world.tgz");
+		try (TarArchiveOutputStream tar = new TarArchiveOutputStream(
+				new GzipCompressorOutputStream(Files.newOutputStream(Files.createFile(tarGzipPath))))) {
+			writeFileToTar(tar, new File(this.gradleBuild.getProjectDir(), "buildpack/hello-world/buildpack.toml"),
+					"buildpack.toml", 0644);
+			writeFileToTar(tar, new File(this.gradleBuild.getProjectDir(), "buildpack/hello-world/bin/detect"),
+					"bin/detect", 0777);
+			writeFileToTar(tar, new File(this.gradleBuild.getProjectDir(), "buildpack/hello-world/bin/build"),
+					"bin/build", 0777);
 		}
 	}
 
+	private void writeFileToTar(TarArchiveOutputStream tar, File file, String name, int mode) throws IOException {
+		TarArchiveEntry entry = new TarArchiveEntry(file, name);
+		entry.setMode(mode);
+		tar.putArchiveEntry(entry);
+		IOUtils.copy(Files.newInputStream(file.toPath()), tar);
+		tar.closeArchiveEntry();
+	}
+
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -17,6 +17,7 @@
 package org.springframework.boot.gradle.tasks.bundling;
 
 import java.io.File;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -28,6 +29,7 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
 import org.springframework.boot.buildpack.platform.build.BuildRequest;
+import org.springframework.boot.buildpack.platform.build.BuildpackReference;
 import org.springframework.boot.buildpack.platform.build.PullPolicy;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -221,4 +223,31 @@ class BootBuildImageTests {
 		assertThat(this.buildImage.createRequest().getPullPolicy()).isEqualTo(PullPolicy.NEVER);
 	}
 
+	@Test
+	void whenNoBuildpacksAreConfiguredThenRequestUsesDefaultBuildpacks() {
+		assertThat(this.buildImage.createRequest().getBuildpacks()).isEmpty();
+	}
+
+	@Test
+	void whenBuildpacksAreConfiguredThenRequestHasBuildpacks() {
+		this.buildImage.setBuildpacks(Arrays.asList("example/buildpack1", "example/buildpack2"));
+		assertThat(this.buildImage.createRequest().getBuildpacks()).containsExactly(
+				BuildpackReference.of("example/buildpack1"), BuildpackReference.of("example/buildpack2"));
+	}
+
+	@Test
+	void whenEntriesAreAddedToBuildpacksThenRequestHasBuildpacks() {
+		this.buildImage.buildpacks(Arrays.asList("example/buildpack1", "example/buildpack2"));
+		assertThat(this.buildImage.createRequest().getBuildpacks()).containsExactly(
+				BuildpackReference.of("example/buildpack1"), BuildpackReference.of("example/buildpack2"));
+	}
+
+	@Test
+	void whenIndividualEntriesAreAddedToBuildpacksThenRequestHasBuildpacks() {
+		this.buildImage.buildpack("example/buildpack1");
+		this.buildImage.buildpack("example/buildpack2");
+		assertThat(this.buildImage.createRequest().getBuildpacks()).containsExactly(
+				BuildpackReference.of("example/buildpack1"), BuildpackReference.of("example/buildpack2"));
+	}
+
 }

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

@@ -37,6 +37,7 @@ import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;
 import com.sun.jna.Platform;
 import io.spring.gradle.dependencymanagement.DependencyManagementPlugin;
 import io.spring.gradle.dependencymanagement.dsl.DependencyManagementExtension;
+import org.antlr.v4.runtime.Lexer;
 import org.apache.commons.compress.archivers.ArchiveEntry;
 import org.apache.http.HttpRequest;
 import org.apache.http.conn.HttpClientConnectionManager;
@@ -49,6 +50,7 @@ import org.jetbrains.kotlin.daemon.client.KotlinCompilerClient;
 import org.jetbrains.kotlin.gradle.model.KotlinProject;
 import org.jetbrains.kotlin.gradle.plugin.KotlinGradleSubplugin;
 import org.jetbrains.kotlin.gradle.plugin.KotlinPlugin;
+import org.tomlj.Toml;
 
 import org.springframework.asm.ClassVisitor;
 import org.springframework.boot.buildpack.platform.build.BuildRequest;
@@ -116,7 +118,8 @@ public class GradleBuild {
 				new File(pathOfJarContaining(HttpRequest.class)), new File(pathOfJarContaining(Module.class)),
 				new File(pathOfJarContaining(Versioned.class)),
 				new File(pathOfJarContaining(ParameterNamesModule.class)),
-				new File(pathOfJarContaining(JsonView.class)), new File(pathOfJarContaining(Platform.class)));
+				new File(pathOfJarContaining(JsonView.class)), new File(pathOfJarContaining(Platform.class)),
+				new File(pathOfJarContaining(Toml.class)), new File(pathOfJarContaining(Lexer.class)));
 	}
 
 	private String pathOfJarContaining(Class<?> type) {

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

@@ -0,0 +1,11 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+bootBuildImage {
+	buildpacks = [ "paketo-buildpacks/java" ]
+}

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

@@ -0,0 +1,11 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+bootBuildImage {
+	buildpacks = [ "file://${projectDir}/buildpack/hello-world" ]
+}

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

@@ -0,0 +1,11 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+bootBuildImage {
+	buildpacks = [ "gcr.io/paketo-buildpacks/java:latest" ]
+}

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

@@ -0,0 +1,11 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+bootBuildImage {
+	buildpacks = [ "file://${projectDir}/hello-world.tgz" ]
+}

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

@@ -0,0 +1,11 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{version}'
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+
+bootBuildImage {
+	buildpacks = [ "urn:cnb:builder:example/does-not-exist:0.0.1" ]
+}