Avoid adding layers for buildpacks that exist in the builder

This commit adds validation of any buildpacks that are specified for
image building to match them against buildpacks that are bundled in
the builder. If an image buildpack's ID, version, and one layer
hash match the same information stored in a label on the builder
image, that buildpack won't be added and the buildpack bundled in
the builder will be used instead. This reduces the chance of adding to
the total count of layers in a builder image unnecessarily.

Fixes gh-31233

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/build/Builder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -105,7 +105,8 @@ public class Builder {
 		Image runImage = imageFetcher.fetchImage(ImageType.RUNNER, request.getRunImage());
 		assertStackIdsMatch(runImage, builderImage);
 		BuildOwner buildOwner = BuildOwner.fromEnv(builderImage.getConfig().getEnv());
-		Buildpacks buildpacks = getBuildpacks(request, imageFetcher, builderMetadata);
+		BuildpackLayersMetadata buildpackLayersMetadata = BuildpackLayersMetadata.fromImage(builderImage);
+		Buildpacks buildpacks = getBuildpacks(request, imageFetcher, builderMetadata, buildpackLayersMetadata);
 		EphemeralBuilder ephemeralBuilder = new EphemeralBuilder(buildOwner, builderImage, request.getName(),
 				builderMetadata, request.getCreator(), request.getEnv(), buildpacks);
 		this.docker.image().load(ephemeralBuilder.getArchive(), UpdateListener.none());
@@ -141,8 +142,10 @@ public class Builder {
 				+ "' does not match builder stack '" + builderImageStackId + "'");
 	}
 
-	private Buildpacks getBuildpacks(BuildRequest request, ImageFetcher imageFetcher, BuilderMetadata builderMetadata) {
-		BuildpackResolverContext resolverContext = new BuilderResolverContext(imageFetcher, builderMetadata);
+	private Buildpacks getBuildpacks(BuildRequest request, ImageFetcher imageFetcher, BuilderMetadata builderMetadata,
+			BuildpackLayersMetadata buildpackLayersMetadata) {
+		BuildpackResolverContext resolverContext = new BuilderResolverContext(imageFetcher, builderMetadata,
+				buildpackLayersMetadata);
 		return BuildpackResolvers.resolveAll(resolverContext, request.getBuildpacks());
 	}
 
@@ -239,9 +242,13 @@ public class Builder {
 
 		private final BuilderMetadata builderMetadata;
 
-		BuilderResolverContext(ImageFetcher imageFetcher, BuilderMetadata builderMetadata) {
+		private final BuildpackLayersMetadata buildpackLayersMetadata;
+
+		BuilderResolverContext(ImageFetcher imageFetcher, BuilderMetadata builderMetadata,
+				BuildpackLayersMetadata buildpackLayersMetadata) {
 			this.imageFetcher = imageFetcher;
 			this.builderMetadata = builderMetadata;
+			this.buildpackLayersMetadata = buildpackLayersMetadata;
 		}
 
 		@Override
@@ -249,6 +256,11 @@ public class Builder {
 			return this.builderMetadata.getBuildpacks();
 		}
 
+		@Override
+		public BuildpackLayersMetadata getBuildpackLayersMetadata() {
+			return this.buildpackLayersMetadata;
+		}
+
 		@Override
 		public Image fetchImage(ImageReference reference, ImageType imageType) throws IOException {
 			return this.imageFetcher.fetchImage(imageType, reference);

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/build/BuildpackLayersMetadata.java

@@ -0,0 +1,194 @@
+/*
+ * Copyright 2012-2022 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.buildpack.platform.build;
+
+import java.io.IOException;
+import java.lang.invoke.MethodHandles;
+import java.util.HashMap;
+import java.util.Map;
+
+import com.fasterxml.jackson.databind.JsonNode;
+
+import org.springframework.boot.buildpack.platform.docker.type.Image;
+import org.springframework.boot.buildpack.platform.docker.type.ImageConfig;
+import org.springframework.boot.buildpack.platform.json.MappedObject;
+import org.springframework.boot.buildpack.platform.json.SharedObjectMapper;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * Buildpack layers metadata information.
+ *
+ * @author Scott Frederick
+ */
+final class BuildpackLayersMetadata extends MappedObject {
+
+	private static final String LABEL_NAME = "io.buildpacks.buildpack.layers";
+
+	private final Buildpacks buildpacks;
+
+	private BuildpackLayersMetadata(JsonNode node) {
+		super(node, MethodHandles.lookup());
+		this.buildpacks = Buildpacks.fromJson(getNode());
+	}
+
+	/**
+	 * Return the metadata details of a buildpack with the given ID and version.
+	 * @param id the buildpack ID
+	 * @param version the buildpack version
+	 * @return the buildpack details or {@code null} if a buildpack with the given ID and
+	 * version does not exist in the metadata
+	 */
+	BuildpackLayerDetails getBuildpack(String id, String version) {
+		return this.buildpacks.getBuildpack(id, version);
+	}
+
+	/**
+	 * Create a {@link BuildpackLayersMetadata} from an image.
+	 * @param image the source image
+	 * @return the buildpack layers metadata
+	 * @throws IOException on IO error
+	 */
+	static BuildpackLayersMetadata fromImage(Image image) throws IOException {
+		Assert.notNull(image, "Image must not be null");
+		return fromImageConfig(image.getConfig());
+	}
+
+	/**
+	 * Create a {@link BuildpackLayersMetadata} from image config.
+	 * @param imageConfig the source image config
+	 * @return the buildpack layers metadata
+	 * @throws IOException on IO error
+	 */
+	static BuildpackLayersMetadata fromImageConfig(ImageConfig imageConfig) throws IOException {
+		Assert.notNull(imageConfig, "ImageConfig must not be null");
+		String json = imageConfig.getLabels().get(LABEL_NAME);
+		Assert.notNull(json, () -> "No '" + LABEL_NAME + "' label found in image config labels '"
+				+ StringUtils.collectionToCommaDelimitedString(imageConfig.getLabels().keySet()) + "'");
+		return fromJson(json);
+	}
+
+	/**
+	 * Create a {@link BuildpackLayersMetadata} from JSON.
+	 * @param json the source JSON
+	 * @return the buildpack layers metadata
+	 * @throws IOException on IO error
+	 */
+	static BuildpackLayersMetadata fromJson(String json) throws IOException {
+		return fromJson(SharedObjectMapper.get().readTree(json));
+	}
+
+	/**
+	 * Create a {@link BuildpackLayersMetadata} from JSON.
+	 * @param node the source JSON
+	 * @return the buildpack layers metadata
+	 */
+	static BuildpackLayersMetadata fromJson(JsonNode node) {
+		return new BuildpackLayersMetadata(node);
+	}
+
+	private static class Buildpacks {
+
+		private final Map<String, BuildpackVersions> buildpacks = new HashMap<>();
+
+		private BuildpackLayerDetails getBuildpack(String id, String version) {
+			if (this.buildpacks.containsKey(id)) {
+				return this.buildpacks.get(id).getBuildpack(version);
+			}
+			return null;
+		}
+
+		private void addBuildpackVersions(String id, BuildpackVersions versions) {
+			this.buildpacks.put(id, versions);
+		}
+
+		private static Buildpacks fromJson(JsonNode node) {
+			Buildpacks buildpacks = new Buildpacks();
+			node.fields().forEachRemaining((field) -> buildpacks.addBuildpackVersions(field.getKey(),
+					BuildpackVersions.fromJson(field.getValue())));
+			return buildpacks;
+		}
+
+	}
+
+	private static class BuildpackVersions {
+
+		private final Map<String, BuildpackLayerDetails> versions = new HashMap<>();
+
+		private BuildpackLayerDetails getBuildpack(String version) {
+			return this.versions.get(version);
+		}
+
+		private void addBuildpackVersion(String version, BuildpackLayerDetails details) {
+			this.versions.put(version, details);
+		}
+
+		private static BuildpackVersions fromJson(JsonNode node) {
+			BuildpackVersions versions = new BuildpackVersions();
+			node.fields().forEachRemaining((field) -> versions.addBuildpackVersion(field.getKey(),
+					BuildpackLayerDetails.fromJson(field.getValue())));
+			return versions;
+		}
+
+	}
+
+	static final class BuildpackLayerDetails extends MappedObject {
+
+		private final String name;
+
+		private final String homepage;
+
+		private final String layerDiffId;
+
+		private BuildpackLayerDetails(JsonNode node) {
+			super(node, MethodHandles.lookup());
+			this.name = valueAt("/name", String.class);
+			this.homepage = valueAt("/homepage", String.class);
+			this.layerDiffId = valueAt("/layerDiffID", String.class);
+		}
+
+		/**
+		 * Return the buildpack name.
+		 * @return the name
+		 */
+		String getName() {
+			return this.name;
+		}
+
+		/**
+		 * Return the buildpack homepage address.
+		 * @return the homepage address
+		 */
+		String getHomepage() {
+			return this.homepage;
+		}
+
+		/**
+		 * Return the buildpack layer {@code diffID}.
+		 * @return the layer {@code diffID}
+		 */
+		String getLayerDiffId() {
+			return this.layerDiffId;
+		}
+
+		private static BuildpackLayerDetails fromJson(JsonNode node) {
+			return new BuildpackLayerDetails(node);
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/build/BuildpackResolverContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -34,6 +34,8 @@ interface BuildpackResolverContext {
 
 	List<BuildpackMetadata> getBuildpackMetadata();
 
+	BuildpackLayersMetadata getBuildpackLayersMetadata();
+
 	/**
 	 * Retrieve an image.
 	 * @param reference the image reference

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/build/ImageBuildpack.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -28,10 +28,12 @@ import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
 import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
 import org.apache.commons.compress.archivers.tar.TarArchiveOutputStream;
 
+import org.springframework.boot.buildpack.platform.build.BuildpackLayersMetadata.BuildpackLayerDetails;
 import org.springframework.boot.buildpack.platform.docker.transport.DockerEngineException;
 import org.springframework.boot.buildpack.platform.docker.type.Image;
 import org.springframework.boot.buildpack.platform.docker.type.ImageReference;
 import org.springframework.boot.buildpack.platform.docker.type.Layer;
+import org.springframework.boot.buildpack.platform.docker.type.LayerId;
 import org.springframework.boot.buildpack.platform.io.IOConsumer;
 import org.springframework.boot.buildpack.platform.io.TarArchive;
 import org.springframework.util.StreamUtils;
@@ -59,13 +61,28 @@ final class ImageBuildpack implements Buildpack {
 			Image image = context.fetchImage(reference, ImageType.BUILDPACK);
 			BuildpackMetadata buildpackMetadata = BuildpackMetadata.fromImage(image);
 			this.coordinates = BuildpackCoordinates.fromBuildpackMetadata(buildpackMetadata);
-			this.exportedLayers = new ExportedLayers(context, reference);
+			if (!buildpackExistsInBuilder(context, image.getLayers())) {
+				this.exportedLayers = new ExportedLayers(context, reference);
+			}
+			else {
+				this.exportedLayers = null;
+			}
 		}
 		catch (IOException | DockerEngineException ex) {
 			throw new IllegalArgumentException("Error pulling buildpack image '" + reference + "'", ex);
 		}
 	}
 
+	private boolean buildpackExistsInBuilder(BuildpackResolverContext context, List<LayerId> imageLayers) {
+		BuildpackLayerDetails buildpackLayerDetails = context.getBuildpackLayersMetadata()
+				.getBuildpack(this.coordinates.getId(), this.coordinates.getVersion());
+		if (buildpackLayerDetails != null) {
+			String layerDiffId = buildpackLayerDetails.getLayerDiffId();
+			return imageLayers.stream().map(LayerId::toString).anyMatch((layerId) -> layerId.equals(layerDiffId));
+		}
+		return false;
+	}
+
 	@Override
 	public BuildpackCoordinates getCoordinates() {
 		return this.coordinates;
@@ -73,7 +90,9 @@ final class ImageBuildpack implements Buildpack {
 
 	@Override
 	public void apply(IOConsumer<Layer> layers) throws IOException {
-		this.exportedLayers.apply(layers);
+		if (this.exportedLayers != null) {
+			this.exportedLayers.apply(layers);
+		}
 	}
 
 	/**

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/java/org/springframework/boot/buildpack/platform/build/BuildpackLayersMetadataTests.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2012-2022 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.buildpack.platform.build;
+
+import java.io.IOException;
+import java.util.Collections;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.buildpack.platform.docker.type.Image;
+import org.springframework.boot.buildpack.platform.docker.type.ImageConfig;
+import org.springframework.boot.buildpack.platform.json.AbstractJsonTests;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link BuildpackLayersMetadata}.
+ *
+ * @author Scott Frederick
+ */
+class BuildpackLayersMetadataTests extends AbstractJsonTests {
+
+	@Test
+	void fromImageLoadsMetadata() throws IOException {
+		Image image = Image.of(getContent("buildpack-image.json"));
+		BuildpackLayersMetadata metadata = BuildpackLayersMetadata.fromImage(image);
+		assertThat(metadata.getBuildpack("example/hello-moon", "0.0.3")).extracting("homepage", "layerDiffId")
+				.containsExactly("https://github.com/example/tree/main/buildpacks/hello-moon",
+						"sha256:4bfdc8714aee68da6662c43bc28d3b41202c88e915641c356523dabe729814c2");
+		assertThat(metadata.getBuildpack("example/hello-world", "0.0.2")).extracting("homepage", "layerDiffId")
+				.containsExactly("https://github.com/example/tree/main/buildpacks/hello-world",
+						"sha256:f752fe099c846e501bdc991d1a22f98c055ddc62f01cfc0495fff2c69f8eb940");
+		assertThat(metadata.getBuildpack("example/hello-world", "version-does-not-exist")).isNull();
+		assertThat(metadata.getBuildpack("id-does-not-exist", "9.9.9")).isNull();
+	}
+
+	@Test
+	void fromImageWhenImageIsNullThrowsException() {
+		assertThatIllegalArgumentException().isThrownBy(() -> BuildpackLayersMetadata.fromImage(null))
+				.withMessage("Image must not be null");
+	}
+
+	@Test
+	void fromImageWhenImageConfigIsNullThrowsException() {
+		Image image = mock(Image.class);
+		assertThatIllegalArgumentException().isThrownBy(() -> BuildpackLayersMetadata.fromImage(image))
+				.withMessage("ImageConfig must not be null");
+	}
+
+	@Test
+	void fromImageConfigWhenLabelIsMissingThrowsException() {
+		Image image = mock(Image.class);
+		ImageConfig imageConfig = mock(ImageConfig.class);
+		given(image.getConfig()).willReturn(imageConfig);
+		given(imageConfig.getLabels()).willReturn(Collections.singletonMap("alpha", "a"));
+		assertThatIllegalArgumentException().isThrownBy(() -> BuildpackLayersMetadata.fromImage(image))
+				.withMessage("No 'io.buildpacks.buildpack.layers' label found in image config labels 'alpha'");
+	}
+
+	@Test
+	void fromJsonLoadsMetadata() throws IOException {
+		BuildpackLayersMetadata metadata = BuildpackLayersMetadata
+				.fromJson(getContentAsString("buildpack-layers-metadata.json"));
+		assertThat(metadata.getBuildpack("example/hello-moon", "0.0.3")).extracting("name", "homepage", "layerDiffId")
+				.containsExactly("Example hello-moon buildpack",
+						"https://github.com/example/tree/main/buildpacks/hello-moon",
+						"sha256:4bfdc8714aee68da6662c43bc28d3b41202c88e915641c356523dabe729814c2");
+		assertThat(metadata.getBuildpack("example/hello-world", "0.0.1")).extracting("name", "homepage", "layerDiffId")
+				.containsExactly("Example hello-world buildpack",
+						"https://github.com/example/tree/main/buildpacks/hello-world",
+						"sha256:1c90e0b80d92555a0523c9ee6500845328fc39ba9dca9d30a877ff759ffbff28");
+		assertThat(metadata.getBuildpack("example/hello-world", "0.0.2")).extracting("name", "homepage", "layerDiffId")
+				.containsExactly("Example hello-world buildpack",
+						"https://github.com/example/tree/main/buildpacks/hello-world",
+						"sha256:f752fe099c846e501bdc991d1a22f98c055ddc62f01cfc0495fff2c69f8eb940");
+		assertThat(metadata.getBuildpack("example/hello-world", "version-does-not-exist")).isNull();
+		assertThat(metadata.getBuildpack("id-does-not-exist", "9.9.9")).isNull();
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/java/org/springframework/boot/buildpack/platform/build/BuildpackResolversTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -84,6 +84,7 @@ class BuildpackResolversTests extends AbstractJsonTests {
 	void resolveAllWithImageBuildpackReferenceReturnsExpectedBuildpack() throws IOException {
 		Image image = Image.of(getContent("buildpack-image.json"));
 		BuildpackResolverContext resolverContext = mock(BuildpackResolverContext.class);
+		given(resolverContext.getBuildpackLayersMetadata()).willReturn(BuildpackLayersMetadata.fromJson("{}"));
 		given(resolverContext.fetchImage(any(), any())).willReturn(image);
 		BuildpackReference reference = BuildpackReference.of("docker://example/buildpack1:latest");
 		Buildpacks buildpacks = BuildpackResolvers.resolveAll(resolverContext, Collections.singleton(reference));

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/java/org/springframework/boot/buildpack/platform/build/ImageBuildpackTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -64,29 +64,31 @@ class ImageBuildpackTests extends AbstractJsonTests {
 	}
 
 	@Test
-	void resolveWhenFullyQualifiedReferenceReturnsBuilder() throws Exception {
+	void resolveWhenFullyQualifiedReferenceReturnsBuildpack() throws Exception {
 		Image image = Image.of(getContent("buildpack-image.json"));
 		ImageReference imageReference = ImageReference.of("example/buildpack1:1.0.0");
 		BuildpackResolverContext resolverContext = mock(BuildpackResolverContext.class);
+		given(resolverContext.getBuildpackLayersMetadata()).willReturn(BuildpackLayersMetadata.fromJson("{}"));
 		given(resolverContext.fetchImage(eq(imageReference), eq(ImageType.BUILDPACK))).willReturn(image);
 		willAnswer(this::withMockLayers).given(resolverContext).exportImageLayers(eq(imageReference), any());
 		BuildpackReference reference = BuildpackReference.of("docker://example/buildpack1:1.0.0");
 		Buildpack buildpack = ImageBuildpack.resolve(resolverContext, reference);
 		assertThat(buildpack.getCoordinates()).hasToString("example/hello-universe@0.0.1");
-		assertHasExpectedLayers(buildpack);
+		assertAppliesExpectedLayers(buildpack);
 	}
 
 	@Test
-	void resolveWhenUnqualifiedReferenceReturnsBuilder() throws Exception {
+	void resolveWhenUnqualifiedReferenceReturnsBuildpack() throws Exception {
 		Image image = Image.of(getContent("buildpack-image.json"));
 		ImageReference imageReference = ImageReference.of("example/buildpack1:1.0.0");
 		BuildpackResolverContext resolverContext = mock(BuildpackResolverContext.class);
+		given(resolverContext.getBuildpackLayersMetadata()).willReturn(BuildpackLayersMetadata.fromJson("{}"));
 		given(resolverContext.fetchImage(eq(imageReference), eq(ImageType.BUILDPACK))).willReturn(image);
 		willAnswer(this::withMockLayers).given(resolverContext).exportImageLayers(eq(imageReference), any());
 		BuildpackReference reference = BuildpackReference.of("example/buildpack1:1.0.0");
 		Buildpack buildpack = ImageBuildpack.resolve(resolverContext, reference);
 		assertThat(buildpack.getCoordinates()).hasToString("example/hello-universe@0.0.1");
-		assertHasExpectedLayers(buildpack);
+		assertAppliesExpectedLayers(buildpack);
 	}
 
 	@Test
@@ -94,12 +96,13 @@ class ImageBuildpackTests extends AbstractJsonTests {
 		Image image = Image.of(getContent("buildpack-image.json"));
 		ImageReference imageReference = ImageReference.of("example/buildpack1:latest");
 		BuildpackResolverContext resolverContext = mock(BuildpackResolverContext.class);
+		given(resolverContext.getBuildpackLayersMetadata()).willReturn(BuildpackLayersMetadata.fromJson("{}"));
 		given(resolverContext.fetchImage(eq(imageReference), eq(ImageType.BUILDPACK))).willReturn(image);
 		willAnswer(this::withMockLayers).given(resolverContext).exportImageLayers(eq(imageReference), any());
 		BuildpackReference reference = BuildpackReference.of("example/buildpack1");
 		Buildpack buildpack = ImageBuildpack.resolve(resolverContext, reference);
 		assertThat(buildpack.getCoordinates()).hasToString("example/hello-universe@0.0.1");
-		assertHasExpectedLayers(buildpack);
+		assertAppliesExpectedLayers(buildpack);
 	}
 
 	@Test
@@ -108,12 +111,28 @@ class ImageBuildpackTests extends AbstractJsonTests {
 		String digest = "sha256:4acb6bfd6c4f0cabaf7f3690e444afe51f1c7de54d51da7e63fac709c56f1c30";
 		ImageReference imageReference = ImageReference.of("example/buildpack1@" + digest);
 		BuildpackResolverContext resolverContext = mock(BuildpackResolverContext.class);
+		given(resolverContext.getBuildpackLayersMetadata()).willReturn(BuildpackLayersMetadata.fromJson("{}"));
 		given(resolverContext.fetchImage(eq(imageReference), eq(ImageType.BUILDPACK))).willReturn(image);
 		willAnswer(this::withMockLayers).given(resolverContext).exportImageLayers(eq(imageReference), any());
 		BuildpackReference reference = BuildpackReference.of("example/buildpack1@" + digest);
 		Buildpack buildpack = ImageBuildpack.resolve(resolverContext, reference);
 		assertThat(buildpack.getCoordinates()).hasToString("example/hello-universe@0.0.1");
-		assertHasExpectedLayers(buildpack);
+		assertAppliesExpectedLayers(buildpack);
+	}
+
+	@Test
+	void resolveWhenBuildpackExistsInBuilderSkipsLayers() throws Exception {
+		Image image = Image.of(getContent("buildpack-image.json"));
+		ImageReference imageReference = ImageReference.of("example/buildpack1:1.0.0");
+		BuildpackResolverContext resolverContext = mock(BuildpackResolverContext.class);
+		given(resolverContext.getBuildpackLayersMetadata())
+				.willReturn(BuildpackLayersMetadata.fromJson(getContentAsString("buildpack-layers-metadata.json")));
+		given(resolverContext.fetchImage(eq(imageReference), eq(ImageType.BUILDPACK))).willReturn(image);
+		willAnswer(this::withMockLayers).given(resolverContext).exportImageLayers(eq(imageReference), any());
+		BuildpackReference reference = BuildpackReference.of("docker://example/buildpack1:1.0.0");
+		Buildpack buildpack = ImageBuildpack.resolve(resolverContext, reference);
+		assertThat(buildpack.getCoordinates()).hasToString("example/hello-universe@0.0.1");
+		assertAppliesNoLayers(buildpack);
 	}
 
 	@Test
@@ -181,7 +200,7 @@ class ImageBuildpackTests extends AbstractJsonTests {
 		tarOut.closeArchiveEntry();
 	}
 
-	private void assertHasExpectedLayers(Buildpack buildpack) throws IOException {
+	private void assertAppliesExpectedLayers(Buildpack buildpack) throws IOException {
 		List<ByteArrayOutputStream> layers = new ArrayList<>();
 		buildpack.apply((layer) -> {
 			ByteArrayOutputStream out = new ByteArrayOutputStream();
@@ -208,4 +227,14 @@ class ImageBuildpackTests extends AbstractJsonTests {
 						TarArchiveEntry.DEFAULT_FILE_MODE));
 	}
 
+	private void assertAppliesNoLayers(Buildpack buildpack) throws IOException {
+		List<ByteArrayOutputStream> layers = new ArrayList<>();
+		buildpack.apply((layer) -> {
+			ByteArrayOutputStream out = new ByteArrayOutputStream();
+			layer.writeTo(out);
+			layers.add(out);
+		});
+		assertThat(layers).isEmpty();
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/resources/org/springframework/boot/buildpack/platform/build/buildpack-layers-metadata.json

@@ -0,0 +1,70 @@
+{
+	"example/hello-moon": {
+		"0.0.3": {
+			"api": "0.2",
+			"stacks": [
+				{
+					"id": "io.buildpacks.stacks.alpine"
+				},
+				{
+					"id": "io.buildpacks.stacks.bionic"
+				}
+			],
+            "name": "Example hello-moon buildpack",
+			"layerDiffID": "sha256:4bfdc8714aee68da6662c43bc28d3b41202c88e915641c356523dabe729814c2",
+			"homepage": "https://github.com/example/tree/main/buildpacks/hello-moon"
+		}
+	},
+	"example/hello-universe": {
+		"0.0.1": {
+			"api": "0.2",
+			"order": [
+				{
+					"group": [
+						{
+							"id": "example/hello-world",
+							"version": "0.0.2"
+						},
+						{
+							"id": "example/hello-moon",
+							"version": "0.0.2"
+						}
+					]
+				}
+			],
+            "name": "Example hello-universe buildpack",
+			"layerDiffID": "sha256:739b4e8f3caae7237584a1bfe029ebdb05403752b1a60a4f9be991b1d51dbb69",
+			"homepage": "https://github.com/example/tree/main/buildpacks/hello-universe"
+		}
+	},
+	"example/hello-world": {
+		"0.0.1": {
+			"api": "0.2",
+			"stacks": [
+				{
+					"id": "io.buildpacks.stacks.alpine"
+				},
+				{
+					"id": "io.buildpacks.stacks.bionic"
+				}
+			],
+            "name": "Example hello-world buildpack",
+			"layerDiffID": "sha256:1c90e0b80d92555a0523c9ee6500845328fc39ba9dca9d30a877ff759ffbff28",
+			"homepage": "https://github.com/example/tree/main/buildpacks/hello-world"
+		},
+		"0.0.2": {
+			"api": "0.2",
+			"stacks": [
+				{
+					"id": "io.buildpacks.stacks.alpine"
+				},
+				{
+					"id": "io.buildpacks.stacks.bionic"
+				}
+			],
+            "name": "Example hello-world buildpack",
+			"layerDiffID": "sha256:f752fe099c846e501bdc991d1a22f98c055ddc62f01cfc0495fff2c69f8eb940",
+			"homepage": "https://github.com/example/tree/main/buildpacks/hello-world"
+		}
+	}
+}