GH-1428 fix(aws): align Custom Runtime error format with Lambda Runtime

Change errorType to fully qualified class name and stackTrace to
JSON array of strings to match the standard Lambda Runtime format.
Also add the Lambda-Runtime-Function-Error-Type header.

Fixes gh-1428
Resolves #1433

Signed-off-by: akenra <37288280+akenra@users.noreply.github.com>

Author: akenra

spring-cloud-function-adapters/spring-cloud-function-adapter-aws/src/main/java/org/springframework/cloud/function/adapter/aws/CustomRuntimeEventLoop.java

@@ -17,16 +17,17 @@
 package org.springframework.cloud.function.adapter.aws;
 
 import java.io.ByteArrayInputStream;
-import java.io.PrintWriter;
-import java.io.StringWriter;
 import java.net.SocketException;
 import java.net.URI;
 import java.nio.charset.StandardCharsets;
 import java.text.MessageFormat;
+import java.util.Arrays;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.stream.Collectors;
 
 import com.amazonaws.services.lambda.runtime.ClientContext;
 import com.amazonaws.services.lambda.runtime.CognitoIdentity;
@@ -72,6 +73,8 @@ public final class CustomRuntimeEventLoop implements SmartLifecycle {
 	private static final String LAMBDA_ERROR_URL_TEMPLATE = "http://{0}/{1}/runtime/invocation/{2}/error";
 	private static final String LAMBDA_RUNTIME_URL_TEMPLATE = "http://{0}/{1}/runtime/invocation/next";
 	private static final String LAMBDA_INVOCATION_URL_TEMPLATE = "http://{0}/{1}/runtime/invocation/{2}/response";
+	private static final String LAMBDA_RUNTIME_FUNCTION_ERROR_TYPE = "Lambda-Runtime-Function-Error-Type";
+
 	private static final String USER_AGENT_VALUE = String.format(
 			"spring-cloud-function/%s-%s",
 			System.getProperty("java.runtime.version"),
@@ -282,12 +285,11 @@ public String toString() {
 
 	private void propagateAwsError(String requestId, Exception e, JsonMapper mapper, String runtimeApi, RestTemplate rest) {
 		String errorMessage = e.getMessage();
-		String errorType = e.getClass().getSimpleName();
-		StringWriter sw = new StringWriter();
-		PrintWriter pw = new PrintWriter(sw);
-		e.printStackTrace(pw);
-		String stackTrace = sw.toString();
-		Map<String, String> em = new HashMap<>();
+		String errorType = e.getClass().getName();
+		List<String> stackTrace = Arrays.stream(e.getStackTrace())
+				.map(StackTraceElement::toString)
+				.collect(Collectors.toList());
+		Map<String, Object> em = new HashMap<>();
 		em.put("errorMessage", errorMessage);
 		em.put("errorType", errorType);
 		em.put("stackTrace", stackTrace);
@@ -296,6 +298,7 @@ private void propagateAwsError(String requestId, Exception e, JsonMapper mapper,
 			String errorUrl = MessageFormat.format(LAMBDA_ERROR_URL_TEMPLATE, runtimeApi, LAMBDA_VERSION_DATE, requestId);
 			ResponseEntity<Object> result = rest.exchange(RequestEntity.post(URI.create(errorUrl))
 					.header(USER_AGENT, USER_AGENT_VALUE)
+					.header(LAMBDA_RUNTIME_FUNCTION_ERROR_TYPE, errorType)
 					.body(outputBody), Object.class);
 			if (logger.isInfoEnabled()) {
 				logger.info("Result ERROR status: " + result.getStatusCode());

spring-cloud-function-adapters/spring-cloud-function-adapter-aws/src/main/java/org/springframework/cloud/function/adapter/test/aws/AWSCustomRuntime.java

@@ -44,6 +44,9 @@ public class AWSCustomRuntime  {
 
 	BlockingQueue<Message<String>> outputQueue = new ArrayBlockingQueue<>(3);
 
+	/** Queue for capturing error responses from the Custom Runtime event loop. */
+	public BlockingQueue<Message<String>> errorQueue = new ArrayBlockingQueue<>(3);
+
 	public AWSCustomRuntime(ConfigurableApplicationContext context) {
 		context.getEnvironment().getPropertySources().addFirst(
 			new MapPropertySource("AWSCustomRuntime",
@@ -55,6 +58,11 @@ Consumer<Message<String>> consume() {
 		return v -> outputQueue.offer(v);
 	}
 
+	@Bean("2018-06-01/runtime/invocation/consume/error")
+	Consumer<Message<String>> consumeError() {
+		return v -> errorQueue.offer(v);
+	}
+
 	@SuppressWarnings("unchecked")
 	@Bean("2018-06-01/runtime/invocation/next")
 	Supplier<Message<String>> supply() {

spring-cloud-function-adapters/spring-cloud-function-adapter-aws/src/test/java/org/springframework/cloud/function/adapter/aws/CustomRuntimeEventLoopTest.java

@@ -16,7 +16,9 @@
 
 package org.springframework.cloud.function.adapter.aws;
 
+import java.util.List;
 import java.util.Locale;
+import java.util.Map;
 import java.util.function.Function;
 
 import org.junit.jupiter.api.Test;
@@ -26,6 +28,7 @@
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.builder.SpringApplicationBuilder;
 import org.springframework.cloud.function.adapter.test.aws.AWSCustomRuntime;
+import org.springframework.cloud.function.json.JsonMapper;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -217,6 +220,76 @@ public void test_definitionLookupAndComposition() throws Exception {
 
 	}
 
+	@Test
+	public void testFunctionThatThrowsException() throws Exception {
+		try (ConfigurableApplicationContext userContext =
+				new SpringApplicationBuilder(ErrorFunctionConfiguration.class, AWSCustomRuntime.class)
+					.web(WebApplicationType.SERVLET)
+					.properties("_HANDLER=hello", "server.port=0")
+					.run()) {
+
+			AWSCustomRuntime aws = userContext.getBean(AWSCustomRuntime.class);
+			JsonMapper mapper = userContext.getBean(JsonMapper.class);
+
+			aws.exchange("\"test\"");
+			Message<String> errorMessage = aws.errorQueue.poll(5000, java.util.concurrent.TimeUnit.MILLISECONDS);
+
+			assertThat(errorMessage).isNotNull();
+			Map<String, Object> errorMap = mapper.fromJson(errorMessage.getPayload(), Map.class);
+
+			assertThat(errorMap)
+				.containsEntry("errorMessage", "Something went wrong")
+				.containsEntry("errorType", "java.lang.RuntimeException")
+				.containsKey("stackTrace");
+			assertThat(errorMap.get("stackTrace")).isInstanceOf(List.class);
+			assertThat((List<?>) errorMap.get("stackTrace"))
+				.isNotEmpty()
+				.first().asString().contains("CustomRuntimeEventLoopTest");
+		}
+	}
+
+	@Test
+	public void testFunctionThatThrowsNestedException() throws Exception {
+		try (ConfigurableApplicationContext userContext =
+				new SpringApplicationBuilder(ErrorFunctionConfiguration.class, AWSCustomRuntime.class)
+					.web(WebApplicationType.SERVLET)
+					.properties("_HANDLER=helloNested", "server.port=0")
+					.run()) {
+
+			AWSCustomRuntime aws = userContext.getBean(AWSCustomRuntime.class);
+			JsonMapper mapper = userContext.getBean(JsonMapper.class);
+
+			aws.exchange("\"test\"");
+			Message<String> errorMessage = aws.errorQueue.poll(5000, java.util.concurrent.TimeUnit.MILLISECONDS);
+
+			assertThat(errorMessage).isNotNull();
+			Map<String, Object> errorMap = mapper.fromJson(errorMessage.getPayload(), Map.class);
+
+			assertThat(errorMap)
+				.containsEntry("errorMessage", "Wrapper exception")
+				.containsEntry("errorType", "java.lang.RuntimeException");
+			assertThat(errorMap.get("stackTrace")).isInstanceOf(List.class);
+		}
+	}
+
+	@EnableAutoConfiguration
+	protected static class ErrorFunctionConfiguration {
+		@Bean
+		public Function<String, String> hello() {
+			return event -> {
+				throw new RuntimeException("Something went wrong");
+			};
+		}
+
+		@Bean
+		public Function<String, String> helloNested() {
+			return event -> {
+				Exception cause = new IllegalStateException("Root cause error");
+				throw new RuntimeException("Wrapper exception", cause);
+			};
+		}
+	}
+
 	@EnableAutoConfiguration
 	protected static class SingleFunctionConfiguration {
 		@Bean