Resources are not cleaned up when resolving an image that is not yet present in the builder

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

@@ -132,35 +132,41 @@ private static class ExportedLayers {
 
 		private Path createLayerFile(TarArchive tarArchive) throws IOException {
 			Path sourceTarFile = Files.createTempFile("create-builder-scratch-source-", null);
-			try (OutputStream out = Files.newOutputStream(sourceTarFile)) {
-				tarArchive.writeTo(out);
-			}
-			Path layerFile = Files.createTempFile("create-builder-scratch-", null);
-			try (TarArchiveOutputStream out = new TarArchiveOutputStream(Files.newOutputStream(layerFile))) {
-				try (TarArchiveInputStream in = new TarArchiveInputStream(Files.newInputStream(sourceTarFile))) {
-					out.setLongFileMode(TarArchiveOutputStream.LONGFILE_POSIX);
-					TarArchiveEntry entry = in.getNextEntry();
-					while (entry != null) {
-						String entryName = entry.getName();
-						Path entryPath = Path.of(entryName);
-						Assert.state(entryPath.toAbsolutePath().equals(entryPath.toAbsolutePath().normalize()),
-								() -> "Malformed zip entry name '%s'".formatted(entryName));
-						out.putArchiveEntry(entry);
-						StreamUtils.copy(in, out);
-						out.closeArchiveEntry();
-						entry = in.getNextEntry();
+			try {
+				try (OutputStream out = Files.newOutputStream(sourceTarFile)) {
+					tarArchive.writeTo(out);
+				}
+				Path layerFile = Files.createTempFile("create-builder-scratch-", null);
+				try (TarArchiveOutputStream out = new TarArchiveOutputStream(Files.newOutputStream(layerFile))) {
+					try (TarArchiveInputStream in = new TarArchiveInputStream(Files.newInputStream(sourceTarFile))) {
+						out.setLongFileMode(TarArchiveOutputStream.LONGFILE_POSIX);
+						TarArchiveEntry entry = in.getNextEntry();
+						while (entry != null) {
+							String entryName = entry.getName();
+							Path entryPath = Path.of(entryName);
+							Assert.state(entryPath.toAbsolutePath().equals(entryPath.toAbsolutePath().normalize()),
+									() -> "Malformed zip entry name '%s'".formatted(entryName));
+							out.putArchiveEntry(entry);
+							StreamUtils.copy(in, out);
+							out.closeArchiveEntry();
+							entry = in.getNextEntry();
+						}
+						out.finish();
 					}
-					out.finish();
 				}
+				return layerFile;
+			}
+			finally {
+				Files.deleteIfExists(sourceTarFile);
 			}
-			return layerFile;
 		}
 
 		void apply(IOConsumer<Layer> layers) throws IOException {
 			for (Path path : this.layerFiles) {
 				layers.accept(Layer.fromTarArchive((out) -> {
-					InputStream in = Files.newInputStream(path);
-					StreamUtils.copy(in, out);
+					try (InputStream in = Files.newInputStream(path)) {
+						StreamUtils.copy(in, out);
+					}
 				}));
 				Files.delete(path);
 			}

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

@@ -24,8 +24,11 @@
 import java.io.IOException;
 import java.nio.file.Files;
 import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Random;
+import java.util.Set;
 
 import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
 import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
@@ -197,6 +200,42 @@ void resolveWhenEntryWouldWriteOutsideOfDestinationThrowsException() throws Exce
 			.withMessage("Malformed zip entry name '../cnb/'");
 	}
 
+	@Test
+	void resolveDeletesIntermediateSourceTarTempFiles() throws Exception {
+		File tempDir = new File(System.getProperty("java.io.tmpdir"));
+		Set<String> tempsBefore = listTempFileNames(tempDir, "create-builder-scratch-");
+		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).isNotNull();
+		Set<String> createdOnResolve = new HashSet<>(listTempFileNames(tempDir, "create-builder-scratch-"));
+		createdOnResolve.removeAll(tempsBefore);
+		assertThat(createdOnResolve).as("intermediate source tar temp files must be deleted after createLayerFile")
+			.noneMatch((name) -> name.startsWith("create-builder-scratch-source-"));
+		assertThat(createdOnResolve).isNotEmpty();
+		assertAppliesExpectedLayers(buildpack);
+		Set<String> remainingCreated = new HashSet<>(listTempFileNames(tempDir, "create-builder-scratch-"));
+		remainingCreated.retainAll(createdOnResolve);
+		assertThat(remainingCreated).as("layer temp files created on resolve must be deleted after apply").isEmpty();
+	}
+
+	private Set<String> listTempFileNames(File tempDir, String prefix) {
+		File[] files = tempDir.listFiles((dir, name) -> name.startsWith(prefix));
+		if (files == null) {
+			return Collections.emptySet();
+		}
+		Set<String> names = new HashSet<>();
+		for (File file : files) {
+			names.add(file.getName());
+		}
+		return names;
+	}
+
 	private @Nullable Object withMockLayers(InvocationOnMock invocation) {
 		return withMockLayers(invocation, "");
 	}