Improve Docker API 5xx error messages

This commit improves the error messages returned by the Spring Boot
build plugins when a 5xx status code is returned from the Docker
API while attempting to build an image. If the error response has
contents containing a JSON structure with a "message" key, the value
associated with that key will be included in the exception message
and in the build plugin output error.

Fixes gh-21515

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

@@ -19,6 +19,7 @@ package org.springframework.boot.buildpack.platform.docker.transport;
 import java.net.URI;
 
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * Exception thrown when a call to the Docker API fails.
@@ -35,11 +36,15 @@ public class DockerEngineException extends RuntimeException {
 
 	private final Errors errors;
 
-	DockerEngineException(String host, URI uri, int statusCode, String reasonPhrase, Errors errors) {
-		super(buildMessage(host, uri, statusCode, reasonPhrase, errors));
+	private final Message responseMessage;
+
+	DockerEngineException(String host, URI uri, int statusCode, String reasonPhrase, Errors errors,
+			Message responseMessage) {
+		super(buildMessage(host, uri, statusCode, reasonPhrase, errors, responseMessage));
 		this.statusCode = statusCode;
 		this.reasonPhrase = reasonPhrase;
 		this.errors = errors;
+		this.responseMessage = responseMessage;
 	}
 
 	/**
@@ -51,7 +56,7 @@ public class DockerEngineException extends RuntimeException {
 	}
 
 	/**
-	 * Return the reason phrase returned by the Docker API error.
+	 * Return the reason phrase returned by the Docker API.
 	 * @return the reasonPhrase
 	 */
 	public String getReasonPhrase() {
@@ -59,24 +64,37 @@ public class DockerEngineException extends RuntimeException {
 	}
 
 	/**
-	 * Return the Errors from the body of the Docker API error, or {@code null} if the
-	 * error JSON could not be read.
+	 * Return the errors from the body of the Docker API response, or {@code null} if the
+	 * errors JSON could not be read.
 	 * @return the errors or {@code null}
 	 */
 	public Errors getErrors() {
 		return this.errors;
 	}
 
-	private static String buildMessage(String host, URI uri, int statusCode, String reasonPhrase, Errors errors) {
-		Assert.notNull(host, "host must not be null");
+	/**
+	 * Return the message from the body of the Docker API response, or {@code null} if the
+	 * message JSON could not be read.
+	 * @return the message or {@code null}
+	 */
+	public Message getResponseMessage() {
+		return this.responseMessage;
+	}
+
+	private static String buildMessage(String host, URI uri, int statusCode, String reasonPhrase, Errors errors,
+			Message responseMessage) {
+		Assert.notNull(host, "Host must not be null");
 		Assert.notNull(uri, "URI must not be null");
 		StringBuilder message = new StringBuilder(
 				"Docker API call to '" + host + uri + "' failed with status code " + statusCode);
-		if (reasonPhrase != null && !reasonPhrase.isEmpty()) {
-			message.append(" \"" + reasonPhrase + "\"");
+		if (!StringUtils.isEmpty(reasonPhrase)) {
+			message.append(" \"").append(reasonPhrase).append("\"");
+		}
+		if (responseMessage != null && !StringUtils.isEmpty(responseMessage.getMessage())) {
+			message.append(" and message \"").append(responseMessage.getMessage()).append("\"");
 		}
 		if (errors != null && !errors.isEmpty()) {
-			message.append(" " + errors);
+			message.append(" ").append(errors);
 		}
 		return message.toString();
 	}

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

@@ -131,8 +131,9 @@ abstract class HttpClientTransport implements HttpTransport {
 			HttpEntity entity = response.getEntity();
 			if (statusCode >= 400 && statusCode <= 500) {
 				Errors errors = (statusCode != 500) ? getErrorsFromResponse(entity) : null;
+				Message message = getMessageFromResponse(entity);
 				throw new DockerEngineException(this.host.toHostString(), request.getURI(), statusCode,
-						statusLine.getReasonPhrase(), errors);
+						statusLine.getReasonPhrase(), errors, message);
 			}
 			return new HttpClientResponse(response);
 		}
@@ -150,6 +151,16 @@ abstract class HttpClientTransport implements HttpTransport {
 		}
 	}
 
+	private Message getMessageFromResponse(HttpEntity entity) {
+		try {
+			return (entity.getContent() != null)
+					? SharedObjectMapper.get().readValue(entity.getContent(), Message.class) : null;
+		}
+		catch (IOException ex) {
+			return null;
+		}
+	}
+
 	HttpHost getHost() {
 		return this.host;
 	}

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

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2012-2020 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.docker.transport;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ * A message returned from the Docker API.
+ *
+ * @author Scott Frederick
+ * @since 2.3.1
+ */
+public class Message {
+
+	private final String message;
+
+	@JsonCreator
+	Message(@JsonProperty("message") String message) {
+		this.message = message;
+	}
+
+	/**
+	 * Return the message contained in the response.
+	 * @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/transport/DockerEngineExceptionTests.java

@@ -49,55 +49,78 @@ class DockerEngineExceptionTests {
 
 	private static final Errors ERRORS = new Errors(Collections.singletonList(new Errors.Error("code", "message")));
 
+	private static final Message NO_MESSAGE = new Message(null);
+
+	private static final Message MESSAGE = new Message("response message");
+
 	@Test
 	void createWhenHostIsNullThrowsException() {
 		assertThatIllegalArgumentException()
-				.isThrownBy(() -> new DockerEngineException(null, null, 404, null, NO_ERRORS))
-				.withMessage("host must not be null");
+				.isThrownBy(() -> new DockerEngineException(null, null, 404, null, NO_ERRORS, NO_MESSAGE))
+				.withMessage("Host must not be null");
 	}
 
 	@Test
 	void createWhenUriIsNullThrowsException() {
 		assertThatIllegalArgumentException()
-				.isThrownBy(() -> new DockerEngineException(HOST, null, 404, null, NO_ERRORS))
+				.isThrownBy(() -> new DockerEngineException(HOST, null, 404, null, NO_ERRORS, NO_MESSAGE))
 				.withMessage("URI must not be null");
 	}
 
 	@Test
 	void create() {
-		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, "missing", ERRORS);
+		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, "missing", ERRORS, MESSAGE);
 		assertThat(exception.getMessage()).isEqualTo(
-				"Docker API call to 'docker://localhost/example' failed with status code 404 \"missing\" [code: message]");
+				"Docker API call to 'docker://localhost/example' failed with status code 404 \"missing\" and message \"response message\" [code: message]");
 		assertThat(exception.getStatusCode()).isEqualTo(404);
 		assertThat(exception.getReasonPhrase()).isEqualTo("missing");
 		assertThat(exception.getErrors()).isSameAs(ERRORS);
+		assertThat(exception.getResponseMessage()).isSameAs(MESSAGE);
 	}
 
 	@Test
 	void createWhenReasonPhraseIsNull() {
-		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, null, ERRORS);
+		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, null, ERRORS, MESSAGE);
 		assertThat(exception.getMessage()).isEqualTo(
-				"Docker API call to 'docker://localhost/example' failed with status code 404 [code: message]");
+				"Docker API call to 'docker://localhost/example' failed with status code 404 and message \"response message\" [code: message]");
 		assertThat(exception.getStatusCode()).isEqualTo(404);
 		assertThat(exception.getReasonPhrase()).isNull();
 		assertThat(exception.getErrors()).isSameAs(ERRORS);
+		assertThat(exception.getResponseMessage()).isSameAs(MESSAGE);
 	}
 
 	@Test
 	void createWhenErrorsIsNull() {
-		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, "missing", null);
+		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, "missing", null, MESSAGE);
+		assertThat(exception.getMessage()).isEqualTo(
+				"Docker API call to 'docker://localhost/example' failed with status code 404 \"missing\" and message \"response message\"");
 		assertThat(exception.getErrors()).isNull();
 	}
 
 	@Test
 	void createWhenErrorsIsEmpty() {
-		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, "missing", NO_ERRORS);
-		assertThat(exception.getMessage())
-				.isEqualTo("Docker API call to 'docker://localhost/example' failed with status code 404 \"missing\"");
+		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, "missing", NO_ERRORS, MESSAGE);
+		assertThat(exception.getMessage()).isEqualTo(
+				"Docker API call to 'docker://localhost/example' failed with status code 404 \"missing\" and message \"response message\"");
 		assertThat(exception.getStatusCode()).isEqualTo(404);
 		assertThat(exception.getReasonPhrase()).isEqualTo("missing");
 		assertThat(exception.getErrors()).isSameAs(NO_ERRORS);
+	}
+
+	@Test
+	void createWhenMessageIsNull() {
+		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, "missing", ERRORS, null);
+		assertThat(exception.getMessage()).isEqualTo(
+				"Docker API call to 'docker://localhost/example' failed with status code 404 \"missing\" [code: message]");
+		assertThat(exception.getResponseMessage()).isNull();
+	}
 
+	@Test
+	void createWhenMessageIsEmpty() {
+		DockerEngineException exception = new DockerEngineException(HOST, URI, 404, "missing", ERRORS, NO_MESSAGE);
+		assertThat(exception.getMessage()).isEqualTo(
+				"Docker API call to 'docker://localhost/example' failed with status code 404 \"missing\" [code: message]");
+		assertThat(exception.getResponseMessage()).isSameAs(NO_MESSAGE);
 	}
 
 }

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

@@ -181,14 +181,42 @@ class HttpClientTransportTests {
 		given(this.entity.getContent()).willReturn(getClass().getResourceAsStream("errors.json"));
 		given(this.statusLine.getStatusCode()).willReturn(404);
 		assertThatExceptionOfType(DockerEngineException.class).isThrownBy(() -> this.http.get(this.uri))
-				.satisfies((ex) -> assertThat(ex.getErrors()).hasSize(2));
+				.satisfies((ex) -> {
+					assertThat(ex.getErrors()).hasSize(2);
+					assertThat(ex.getResponseMessage()).isNull();
+				});
 	}
 
 	@Test
-	void executeWhenResponseIsIn500RangeShouldThrowDockerException() {
+	void executeWhenResponseIsIn500RangeWithNoContentShouldThrowDockerException() {
 		given(this.statusLine.getStatusCode()).willReturn(500);
 		assertThatExceptionOfType(DockerEngineException.class).isThrownBy(() -> this.http.get(this.uri))
-				.satisfies((ex) -> assertThat(ex.getErrors()).isNull());
+				.satisfies((ex) -> {
+					assertThat(ex.getErrors()).isNull();
+					assertThat(ex.getResponseMessage()).isNull();
+				});
+	}
+
+	@Test
+	void executeWhenResponseIsIn500RangeWithMessageShouldThrowDockerException() throws IOException {
+		given(this.entity.getContent()).willReturn(getClass().getResourceAsStream("message.json"));
+		given(this.statusLine.getStatusCode()).willReturn(500);
+		assertThatExceptionOfType(DockerEngineException.class).isThrownBy(() -> this.http.get(this.uri))
+				.satisfies((ex) -> {
+					assertThat(ex.getErrors()).isNull();
+					assertThat(ex.getResponseMessage().getMessage()).contains("test message");
+				});
+	}
+
+	@Test
+	void executeWhenResponseIsIn500RangeWithOtherContentShouldThrowDockerException() throws IOException {
+		given(this.entity.getContent()).willReturn(this.content);
+		given(this.statusLine.getStatusCode()).willReturn(500);
+		assertThatExceptionOfType(DockerEngineException.class).isThrownBy(() -> this.http.get(this.uri))
+				.satisfies((ex) -> {
+					assertThat(ex.getErrors()).isNull();
+					assertThat(ex.getResponseMessage()).isNull();
+				});
 	}
 
 	@Test

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

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2012-2020 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.docker.transport;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.buildpack.platform.json.AbstractJsonTests;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link Message}.
+ *
+ * @author Scott Frederick
+ */
+class MessageTests extends AbstractJsonTests {
+
+	@Test
+	void readValueDeserializesJson() throws Exception {
+		Message message = getObjectMapper().readValue(getContent("message.json"), Message.class);
+		assertThat(message.getMessage()).isEqualTo("test message");
+	}
+
+	@Test
+	void toStringHasErrorDetails() throws Exception {
+		Message errors = getObjectMapper().readValue(getContent("message.json"), Message.class);
+		assertThat(errors.toString()).isEqualTo("test message");
+	}
+
+}

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

@@ -0,0 +1,3 @@
+{
+	"message": "test message"
+}