Ignore response body in eureka client on 404 error.

This allows heartbeats to proceed as normal.

Fixes gh-4145

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/http/RestTemplateTransportClientFactory.java

@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.netflix.eureka.http;
 
+import java.io.IOException;
+import java.io.InputStream;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.Optional;
@@ -44,8 +46,11 @@
 
 import org.springframework.cloud.configuration.SSLContextFactory;
 import org.springframework.cloud.configuration.TlsProperties;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.http.client.ClientHttpRequestFactory;
+import org.springframework.http.client.ClientHttpResponse;
 import org.springframework.http.client.support.BasicAuthenticationInterceptor;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
 import org.springframework.web.client.DefaultResponseErrorHandler;
@@ -113,7 +118,9 @@ private String stripUserInfo(String serviceUrl) {
 	}
 
 	private RestTemplate restTemplate(String serviceUrl) {
-		RestTemplate restTemplate = restTemplate();
+		ClientHttpRequestFactory requestFactory = this.eurekaClientHttpRequestFactorySupplier
+				.get(this.sslContext.orElse(null), this.hostnameVerifier.orElse(null));
+		RestTemplate restTemplate = new RestTemplate(requestFactory);
 
 		try {
 			URI serviceURI = new URI(serviceUrl);
@@ -132,13 +139,15 @@ private RestTemplate restTemplate(String serviceUrl) {
 		restTemplate.getMessageConverters().add(0, mappingJacksonHttpMessageConverter());
 		restTemplate.setErrorHandler(new ErrorHandler());
 
-		return restTemplate;
-	}
+		restTemplate.getInterceptors().add((request, body, execution) -> {
+			ClientHttpResponse response = execution.execute(request, body);
+			if (!response.getStatusCode().equals(HttpStatus.NOT_FOUND)) {
+				return response;
+			}
+			return new NotFoundHttpResponse(response);
+		});
 
-	private RestTemplate restTemplate() {
-		ClientHttpRequestFactory requestFactory = this.eurekaClientHttpRequestFactorySupplier
-				.get(this.sslContext.orElse(null), this.hostnameVerifier.orElse(null));
-		return new RestTemplate(requestFactory);
+		return restTemplate;
 	}
 
 	/**
@@ -172,11 +181,6 @@ public static BeanSerializerModifier createJsonSerializerModifier() {
 			@Override
 			public JsonSerializer<?> modifySerializer(SerializationConfig config, BeanDescription beanDesc,
 					JsonSerializer<?> serializer) {
-				/*
-				 * if (beanDesc.getBeanClass().isAssignableFrom(Applications.class)) {
-				 * return new ApplicationsJsonBeanSerializer((BeanSerializerBase)
-				 * serializer, keyFormatter); }
-				 */
 				if (beanDesc.getBeanClass().isAssignableFrom(InstanceInfo.class)) {
 					return new InstanceInfoJsonBeanSerializer((BeanSerializerBase) serializer, false);
 				}
@@ -189,6 +193,50 @@ public JsonSerializer<?> modifySerializer(SerializationConfig config, BeanDescri
 	public void shutdown() {
 	}
 
+	/**
+	 * Response that ignores body, specifically for 404 errors.
+	 */
+	private static class NotFoundHttpResponse implements ClientHttpResponse {
+
+		private final ClientHttpResponse response;
+
+		NotFoundHttpResponse(ClientHttpResponse response) {
+			this.response = response;
+		}
+
+		@Override
+		public HttpStatusCode getStatusCode() throws IOException {
+			return response.getStatusCode();
+		}
+
+		@Override
+		public int getRawStatusCode() throws IOException {
+			return response.getRawStatusCode();
+		}
+
+		@Override
+		public String getStatusText() throws IOException {
+			return response.getStatusText();
+		}
+
+		@Override
+		public void close() {
+			response.close();
+		}
+
+		@Override
+		public InputStream getBody() throws IOException {
+			// ignore body on 404 for heartbeat, see gh-4145
+			return null;
+		}
+
+		@Override
+		public HttpHeaders getHeaders() {
+			return response.getHeaders();
+		}
+
+	}
+
 	class ErrorHandler extends DefaultResponseErrorHandler {
 
 		@Override

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/http/WebClientTransportClientFactory.java

@@ -38,6 +38,7 @@
 import com.netflix.discovery.shared.resolver.EurekaEndpoint;
 import com.netflix.discovery.shared.transport.EurekaHttpClient;
 import com.netflix.discovery.shared.transport.TransportClientFactory;
+import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 import org.springframework.http.HttpStatus;
@@ -151,6 +152,12 @@ private ExchangeFilterFunction http4XxErrorExchangeFilterFunction() {
 				newResponse.body((clientHttpResponse, context) -> clientHttpResponse.getBody());
 				return Mono.just(newResponse);
 			}
+			if (clientResponse.statusCode().equals(HttpStatus.NOT_FOUND)) {
+				ClientResponse newResponse = clientResponse.mutate().statusCode(clientResponse.statusCode())
+						// ignore body on 404 for heartbeat, see gh-4145
+						.body(Flux.empty()).build();
+				return Mono.just(newResponse);
+			}
 			return Mono.just(clientResponse);
 		});
 	}

spring-cloud-netflix-eureka-client/src/test/java/org/springframework/cloud/netflix/eureka/http/AbstractEurekaHttpClientTests.java

@@ -19,6 +19,7 @@
 import com.netflix.appinfo.InstanceInfo;
 import com.netflix.discovery.shared.Applications;
 import com.netflix.discovery.shared.transport.EurekaHttpClient;
+import com.netflix.discovery.shared.transport.EurekaHttpResponse;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.http.HttpStatus;
@@ -48,8 +49,9 @@ void testCancel() {
 
 	@Test
 	void testSendHeartBeat() {
-		assertThat(eurekaHttpClient.sendHeartBeat("test", "test", info, null).getStatusCode())
-				.isEqualTo(HttpStatus.OK.value());
+		EurekaHttpResponse<InstanceInfo> response = eurekaHttpClient.sendHeartBeat("test", "test", info, null);
+		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK.value());
+		assertThat(response.getEntity()).isNotNull();
 	}
 
 	@Test
@@ -58,6 +60,12 @@ void testSendHeartBeatFourOFour() {
 				.isEqualTo(HttpStatus.NOT_FOUND.value());
 	}
 
+	@Test
+	void testSendHeartBeatFourOFourWithBody() {
+		assertThat(eurekaHttpClient.sendHeartBeat("fourOFourWithBody", "test", info, null).getStatusCode())
+				.isEqualTo(HttpStatus.NOT_FOUND.value());
+	}
+
 	@Test
 	void testStatusUpdate() {
 		assertThat(eurekaHttpClient.statusUpdate("test", "test", InstanceInfo.InstanceStatus.UP, info).getStatusCode())

spring-cloud-netflix-eureka-client/src/test/java/org/springframework/cloud/netflix/eureka/http/EurekaServerMockApplication.java

@@ -118,6 +118,11 @@ public ResponseEntity sendHeartBeat(@PathVariable String appName, @PathVariable
 		if ("fourOFour".equals(appName)) {
 			return new ResponseEntity(HttpStatus.NOT_FOUND);
 		}
+		if ("fourOFourWithBody".equals(appName)) {
+			return new ResponseEntity(
+					"{ \"error\": \"Not Found\", \"message\": null, \"path\": \"/1\", \"requestId\": \"9e5d3244-1\", \"status\": 404, \"timestamp\": \"2023-03-04T03:31:20.810+00:00\" }",
+					HttpStatus.NOT_FOUND);
+		}
 		return new ResponseEntity<>(new InstanceInfo(null, null, null, null, null, null, null, null, null, null, null,
 				null, null, 0, null, null, null, null, null, null, null, new HashMap<>(), 0L, 0L, null, null),
 				HttpStatus.OK);