Improve error reporting when image loading fails

Closes gh-31243

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/docker/DockerApi.java

@@ -233,7 +233,7 @@ public void load(ImageArchive archive, UpdateListener<LoadImageUpdateEvent> list
 			Assert.notNull(archive, "Archive must not be null");
 			Assert.notNull(listener, "Listener must not be null");
 			URI loadUri = buildUrl("/images/load");
-			StreamCaptureUpdateListener streamListener = new StreamCaptureUpdateListener();
+			LoadImageUpdateListener streamListener = new LoadImageUpdateListener(archive);
 			listener.onStart();
 			try {
 				try (Response response = http().post(loadUri, "application/x-tar", archive::writeTo)) {
@@ -242,9 +242,7 @@ public void load(ImageArchive archive, UpdateListener<LoadImageUpdateEvent> list
 						listener.onUpdate(event);
 					});
 				}
-				Assert.state(StringUtils.hasText(streamListener.getCapturedStream()),
-						"Invalid response received when loading image "
-								+ ((archive.getTag() != null) ? "\"" + archive.getTag() + "\"" : ""));
+				streamListener.assertValidResponseReceived();
 			}
 			finally {
 				listener.onFinish();
@@ -482,19 +480,33 @@ public void onUpdate(ProgressUpdateEvent event) {
 	}
 
 	/**
-	 * {@link UpdateListener} used to ensure an image load response stream.
+	 * {@link UpdateListener} for an image load response stream.
 	 */
-	private static final class StreamCaptureUpdateListener implements UpdateListener<LoadImageUpdateEvent> {
+	private static final class LoadImageUpdateListener implements UpdateListener<LoadImageUpdateEvent> {
+
+		private final ImageArchive archive;
 
 		private String stream;
 
+		private LoadImageUpdateListener(ImageArchive archive) {
+			this.archive = archive;
+		}
+
 		@Override
 		public void onUpdate(LoadImageUpdateEvent event) {
+			Assert.state(event.getErrorDetail() == null,
+					() -> "Error response received when loading image" + image() + ": " + event.getErrorDetail());
 			this.stream = event.getStream();
 		}
 
-		String getCapturedStream() {
-			return this.stream;
+		private String image() {
+			ImageReference tag = this.archive.getTag();
+			return (tag != null) ? " \"" + tag + "\"" : "";
+		}
+
+		private void assertValidResponseReceived() {
+			Assert.state(StringUtils.hasText(this.stream),
+					() -> "Invalid response received when loading image" + image());
 		}
 
 	}

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/docker/LoadImageUpdateEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2024 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.buildpack.platform.docker;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
 
 /**
  * A {@link ProgressUpdateEvent} fired as an image is loaded.
@@ -28,10 +29,14 @@ public class LoadImageUpdateEvent extends ProgressUpdateEvent {
 
 	private final String stream;
 
+	private final ErrorDetail errorDetail;
+
 	@JsonCreator
-	public LoadImageUpdateEvent(String stream, String status, ProgressDetail progressDetail, String progress) {
+	public LoadImageUpdateEvent(String stream, String status, ProgressDetail progressDetail, String progress,
+			ErrorDetail errorDetail) {
 		super(status, progressDetail, progress);
 		this.stream = stream;
+		this.errorDetail = errorDetail;
 	}
 
 	/**
@@ -42,4 +47,42 @@ public String getStream() {
 		return this.stream;
 	}
 
+	/**
+	 * Return the error detail or {@code null} if no error occurred.
+	 * @return the error detail, if any
+	 * @since 3.2.12
+	 */
+	public ErrorDetail getErrorDetail() {
+		return this.errorDetail;
+	}
+
+	/**
+	 * Details of an error embedded in a response stream.
+	 *
+	 * @since 3.2.12
+	 */
+	public static class ErrorDetail {
+
+		private final String message;
+
+		@JsonCreator
+		public ErrorDetail(@JsonProperty("message") String message) {
+			this.message = message;
+		}
+
+		/**
+		 * Returns the message field from the error detail.
+		 * @return the message
+		 */
+		public String getMessage() {
+			return this.message;
+		}
+
+		@Override
+		public String toString() {
+			return this.message;
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/java/org/springframework/boot/buildpack/platform/docker/DockerApiTests.java

@@ -252,6 +252,16 @@ void loadWithEmptyResponseThrowsException() throws Exception {
 				.withMessageContaining("Invalid response received");
 		}
 
+		@Test // gh-31243
+		void loadWithErrorResponseThrowsException() throws Exception {
+			Image image = Image.of(getClass().getResourceAsStream("type/image.json"));
+			ImageArchive archive = ImageArchive.from(image);
+			URI loadUri = new URI(IMAGES_URL + "/load");
+			given(http().post(eq(loadUri), eq("application/x-tar"), any())).willReturn(responseOf("load-error.json"));
+			assertThatIllegalStateException().isThrownBy(() -> this.api.load(archive, this.loadListener))
+				.withMessageContaining("Error response received");
+		}
+
 		@Test
 		void loadLoadsImage() throws Exception {
 			Image image = Image.of(getClass().getResourceAsStream("type/image.json"));

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/java/org/springframework/boot/buildpack/platform/docker/LoadImageUpdateEventTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -18,6 +18,7 @@
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.boot.buildpack.platform.docker.LoadImageUpdateEvent.ErrorDetail;
 import org.springframework.boot.buildpack.platform.docker.ProgressUpdateEvent.ProgressDetail;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -36,9 +37,16 @@ void getStreamReturnsStream() {
 		assertThat(event.getStream()).isEqualTo("stream");
 	}
 
+	@Test
+	void getErrorDetailReturnsErrorDetail() {
+		LoadImageUpdateEvent event = createEvent();
+		assertThat(event.getErrorDetail()).extracting(ErrorDetail::getMessage).isEqualTo("max depth exceeded");
+	}
+
 	@Override
 	protected LoadImageUpdateEvent createEvent(String status, ProgressDetail progressDetail, String progress) {
-		return new LoadImageUpdateEvent("stream", status, progressDetail, progress);
+		return new LoadImageUpdateEvent("stream", status, progressDetail, progress,
+				new ErrorDetail("max depth exceeded"));
 	}
 
 }

spring-boot-project/spring-boot-tools/spring-boot-buildpack-platform/src/test/resources/org/springframework/boot/buildpack/platform/docker/load-error.json

@@ -0,0 +1 @@
+{"errorDetail":{"message":"max depth exceeded"}}