Correct LocalResponseCache behaviour w/ "no-cache", "must-revalidate", "max-age" and "no-store" directives

summary:

1. Inputs / expected result in order assuming Cache TTL configured to 120s
* Request contains `no-store` or `private`
  * (done) Cache is skipped without storing response and `Cache-Control` will come from upstream
* Request contains `no-cache`
  * The cached response is ignored by SCG dispatching to upstream(we cannot return 304 - imagine a client sends no-cache waiting for the server to revalidate and returns fresh data but instead it receives a bodyless response 304)
    * A) Fresh response coming from upstream is renewed in the SCG cache and `Cache-Control: max-age=120s`. Other clients will see max-age increased
    * B) Fresh response coming from upstream is not stored. Other clients will not be affected.
* Otherwise (ignoring `ETag`, `If-Modified-Since` and other request directives
  * if Response is not cached in SCG yet
    * `Cache-Control: max-age=120` (no-cache, no-store and must-revalidate doesn't make sense)
  * if Response is cached in SCG with remaining TTL = 30s
    * `Cache-Control: max-age=30` (no-cache, no-store and must-revalidate doesn't make sense)
  * if Response is cached in SCG with remaining TTL = 0s
    * `Cache-Control: max-age=0,no-cache,must-revalidate` (max-age=0+must-revalidate is equivalent to no-cache)

2. Revalidation is out of scope but it can be added in the future (ETag, If-Modified-Since, Modified-Since)

README.adoc

@@ -6,7 +6,7 @@ Edit the files in the src/main/asciidoc/ directory instead.
 
 
 image::https://github.com/spring-cloud/spring-cloud-gateway/workflows/Build/badge.svg?style=svg["Actions Status", link="https://github.com/spring-cloud/spring-cloud-gateway/actions"]
-image::https://codecov.io/gh/spring-cloud/spring-cloud-gateway/branch/main/graph/badge.svg["Codecov", link="https://codecov.io/gh/spring-cloud/spring-cloud-gateway/branch/main"]
+image::https://codecov.io/gh/spring-cloud/spring-cloud-gateway/branch/4.0.x/graph/badge.svg["Codecov", link="https://codecov.io/gh/spring-cloud/spring-cloud-gateway/branch/main"]
 
 
 This project provides an API Gateway built on top of the Spring Ecosystem, including: Spring 6, Spring Boot 3 and Project Reactor. Spring Cloud Gateway aims to provide a simple, yet effective way to route to APIs and provide cross cutting concerns to them such as: security, monitoring/metrics, and resiliency.
@@ -109,7 +109,7 @@ from the `file` menu.
 
 == Contributing
 
-:spring-cloud-build-branch: 4.0.x
+:spring-cloud-build-branch: master
 
 Spring Cloud is released under the non-restrictive Apache 2.0 license,
 and follows a very standard Github development process, using Github
@@ -126,7 +126,7 @@ author credit if we do.  Active contributors might be asked to join the core tea
 given the ability to merge pull requests.
 
 === Code of Conduct
-This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/master/docs/src/main/asciidoc/code-of-conduct.adoc[code of
+This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/{spring-cloud-build-branch}/docs/src/main/asciidoc/code-of-conduct.adoc[code of
 conduct]. By participating, you  are expected to uphold this code. Please report
 unacceptable behavior to spring-code-of-conduct@pivotal.io.
 
@@ -137,7 +137,7 @@ added after the original pull request but before a merge.
 * Use the Spring Framework code format conventions. If you use Eclipse
   you can import formatter settings using the
   `eclipse-code-formatter.xml` file from the
-  https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring
+  https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring
   Cloud Build] project. If using IntelliJ, you can use the
   https://plugins.jetbrains.com/plugin/6546[Eclipse Code Formatter
   Plugin] to import the same file.

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/config/LocalResponseCacheAutoConfiguration.java

@@ -65,7 +65,7 @@ public class LocalResponseCacheAutoConfiguration {
 			@Qualifier(RESPONSE_CACHE_MANAGER_NAME) CacheManager cacheManager,
 			LocalResponseCacheProperties properties) {
 		return new GlobalLocalResponseCacheGatewayFilter(responseCacheManagerFactory, responseCache(cacheManager),
-				properties.getTimeToLive());
+				properties.getTimeToLive(), properties.getRequest());
 	}
 
 	@Bean(name = RESPONSE_CACHE_MANAGER_NAME)
@@ -78,7 +78,7 @@ public class LocalResponseCacheAutoConfiguration {
 	public LocalResponseCacheGatewayFilterFactory localResponseCacheGatewayFilterFactory(
 			ResponseCacheManagerFactory responseCacheManagerFactory, LocalResponseCacheProperties properties) {
 		return new LocalResponseCacheGatewayFilterFactory(responseCacheManagerFactory, properties.getTimeToLive(),
-				properties.getSize());
+				properties.getSize(), properties.getRequest());
 	}
 
 	@Bean

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/GlobalLocalResponseCacheGatewayFilter.java

@@ -41,9 +41,9 @@ public class GlobalLocalResponseCacheGatewayFilter implements GlobalFilter, Orde
 	private final ResponseCacheGatewayFilter responseCacheGatewayFilter;
 
 	public GlobalLocalResponseCacheGatewayFilter(ResponseCacheManagerFactory cacheManagerFactory, Cache globalCache,
-			Duration configuredTimeToLive) {
+			Duration configuredTimeToLive, LocalResponseCacheRequestOptions requestOptions) {
 		responseCacheGatewayFilter = new ResponseCacheGatewayFilter(
-				cacheManagerFactory.create(globalCache, configuredTimeToLive));
+				cacheManagerFactory.create(globalCache, configuredTimeToLive, requestOptions));
 	}
 
 	@Override

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/LocalResponseCacheGatewayFilterFactory.java

@@ -30,11 +30,9 @@ import org.springframework.validation.annotation.Validated;
 
 /**
  * {@link org.springframework.cloud.gateway.filter.factory.GatewayFilterFactory} of
- * {@link ResponseCacheGatewayFilter}.
- *
- * By default, a global cache (defined as properties in the application) is used. For
- * specific route configuration, parameters can be added following
- * {@link RouteCacheConfiguration} class.
+ * {@link ResponseCacheGatewayFilter}. By default, a global cache (defined as properties
+ * in the application) is used. For specific route configuration, parameters can be added
+ * following {@link RouteCacheConfiguration} class.
  *
  * @author Marta Medio
  * @author Ignacio Lozano
@@ -49,23 +47,21 @@ public class LocalResponseCacheGatewayFilterFactory
 	 */
 	public static final String LOCAL_RESPONSE_CACHE_FILTER_APPLIED = "LocalResponseCacheGatewayFilter-Applied";
 
-	private ResponseCacheManagerFactory cacheManagerFactory;
+	private final ResponseCacheManagerFactory cacheManagerFactory;
 
-	private Duration defaultTimeToLive;
+	private final Duration defaultTimeToLive;
 
-	private DataSize defaultSize;
+	private final DataSize defaultSize;
 
-	public LocalResponseCacheGatewayFilterFactory(ResponseCacheManagerFactory cacheManagerFactory,
-			Duration defaultTimeToLive) {
-		this(cacheManagerFactory, defaultTimeToLive, null);
-	}
+	private final LocalResponseCacheRequestOptions requestOptions;
 
 	public LocalResponseCacheGatewayFilterFactory(ResponseCacheManagerFactory cacheManagerFactory,
-			Duration defaultTimeToLive, DataSize defaultSize) {
+			Duration defaultTimeToLive, DataSize defaultSize, LocalResponseCacheRequestOptions requestOptions) {
 		super(RouteCacheConfiguration.class);
 		this.cacheManagerFactory = cacheManagerFactory;
 		this.defaultTimeToLive = defaultTimeToLive;
 		this.defaultSize = defaultSize;
+		this.requestOptions = requestOptions;
 	}
 
 	@Override
@@ -74,7 +70,8 @@ public class LocalResponseCacheGatewayFilterFactory
 
 		Cache routeCache = LocalResponseCacheAutoConfiguration.createGatewayCacheManager(cacheProperties)
 				.getCache(config.getRouteId() + "-cache");
-		return new ResponseCacheGatewayFilter(cacheManagerFactory.create(routeCache, cacheProperties.getTimeToLive()));
+		return new ResponseCacheGatewayFilter(
+				cacheManagerFactory.create(routeCache, cacheProperties.getTimeToLive(), requestOptions));
 
 	}
 

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/LocalResponseCacheProperties.java

@@ -40,6 +40,8 @@ public class LocalResponseCacheProperties {
 
 	private Duration timeToLive;
 
+	private LocalResponseCacheRequestOptions request = new LocalResponseCacheRequestOptions();
+
 	public DataSize getSize() {
 		return size;
 	}
@@ -64,9 +66,18 @@ public class LocalResponseCacheProperties {
 		this.timeToLive = timeToLive;
 	}
 
+	public LocalResponseCacheRequestOptions getRequest() {
+		return request;
+	}
+
+	public void setRequest(LocalResponseCacheRequestOptions request) {
+		this.request = request;
+	}
+
 	@Override
 	public String toString() {
-		return "LocalResponseCacheProperties{" + "timeToLive=" + getTimeToLive() + '\'' + ", size='" + getSize() + '}';
+		return "LocalResponseCacheProperties{" + "size=" + size + ", timeToLive=" + timeToLive + ", request=" + request
+				+ '}';
 	}
 
 }

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/LocalResponseCacheRequestOptions.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2013-2023 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.cloud.gateway.filter.factory.cache;
+
+public class LocalResponseCacheRequestOptions {
+
+	private RequestNoCacheDirectiveStrategy noCache = RequestNoCacheDirectiveStrategy.SKIP_UPDATE_CACHE_ENTRY;
+
+	public RequestNoCacheDirectiveStrategy getNoCache() {
+		return noCache;
+	}
+
+	public void setNoCache(RequestNoCacheDirectiveStrategy noCache) {
+		this.noCache = noCache;
+	}
+
+}

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/LocalResponseCacheUtils.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2013-2020 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.cloud.gateway.filter.factory.cache;
+
+import java.util.Optional;
+
+import org.springframework.http.server.reactive.ServerHttpRequest;
+
+public final class LocalResponseCacheUtils {
+
+	private LocalResponseCacheUtils() {
+	}
+
+	public static boolean isNoCacheRequest(ServerHttpRequest request) {
+		return Optional.ofNullable(request.getHeaders().getCacheControl())
+				.filter(cc -> cc.matches(".*(\s|,|^)no-cache(\\s|,|$).*")).isPresent();
+	}
+
+}

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/RequestNoCacheDirectiveStrategy.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2013-2022 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.cloud.gateway.filter.factory.cache;
+
+/**
+ * When client sends "no-cache" directive in "Cache-Control" header, the response should
+ * be re-validated from upstream. There are several strategies that indicates what to do
+ * with the new fresh response.
+ */
+public enum RequestNoCacheDirectiveStrategy {
+
+	/**
+	 * Update the cache entry by the fresh response coming from upstream with a new time
+	 * to live.
+	 */
+	UPDATE_CACHE_ENTRY,
+	/**
+	 * Skip the update. The client will receive the fresh response, other clients will
+	 * receive the old entry in cache.
+	 */
+	SKIP_UPDATE_CACHE_ENTRY
+
+}

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/ResponseCacheGatewayFilter.java

@@ -66,7 +66,7 @@ public class ResponseCacheGatewayFilter implements GatewayFilter, Ordered {
 
 	private Mono<Void> filterWithCache(ServerWebExchange exchange, GatewayFilterChain chain) {
 		final String metadataKey = responseCacheManager.resolveMetadataKey(exchange);
-		Optional<CachedResponse> cached = responseCacheManager.getFromCache(exchange.getRequest(), metadataKey);
+		Optional<CachedResponse> cached = getCachedResponse(exchange, metadataKey);
 
 		if (cached.isPresent()) {
 			return responseCacheManager.processFromCache(exchange, metadataKey, cached.get());
@@ -77,6 +77,22 @@ public class ResponseCacheGatewayFilter implements GatewayFilter, Ordered {
 		}
 	}
 
+	private Optional<CachedResponse> getCachedResponse(ServerWebExchange exchange, String metadataKey) {
+		Optional<CachedResponse> cached;
+		if (shouldRevalidate(exchange)) {
+			cached = Optional.empty();
+		}
+		else {
+			cached = responseCacheManager.getFromCache(exchange.getRequest(), metadataKey);
+		}
+
+		return cached;
+	}
+
+	private boolean shouldRevalidate(ServerWebExchange exchange) {
+		return LocalResponseCacheUtils.isNoCacheRequest(exchange.getRequest());
+	}
+
 	private class CachingResponseDecorator extends ServerHttpResponseDecorator {
 
 		private final String metadataKey;
@@ -94,7 +110,8 @@ public class ResponseCacheGatewayFilter implements GatewayFilter, Ordered {
 			final ServerHttpResponse response = exchange.getResponse();
 
 			Flux<DataBuffer> decoratedBody;
-			if (responseCacheManager.isResponseCacheable(response)) {
+			if (responseCacheManager.isResponseCacheable(response)
+					&& !responseCacheManager.isNoCacheRequestWithoutUpdate(exchange.getRequest())) {
 				decoratedBody = responseCacheManager.processFromUpstream(metadataKey, exchange, Flux.from(body));
 			}
 			else {

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/ResponseCacheManager.java

@@ -32,6 +32,7 @@ import reactor.core.publisher.Mono;
 import org.springframework.cache.Cache;
 import org.springframework.cloud.gateway.filter.factory.cache.keygenerator.CacheKeyGenerator;
 import org.springframework.cloud.gateway.filter.factory.cache.postprocessor.AfterCacheExchangeMutator;
+import org.springframework.cloud.gateway.filter.factory.cache.postprocessor.SetCacheDirectivesByMaxAgeAfterCacheExchangeMutator;
 import org.springframework.cloud.gateway.filter.factory.cache.postprocessor.SetMaxAgeHeaderAfterCacheExchangeMutator;
 import org.springframework.cloud.gateway.filter.factory.cache.postprocessor.SetResponseHeadersAfterCacheExchangeMutator;
 import org.springframework.cloud.gateway.filter.factory.cache.postprocessor.SetStatusCodeAfterCacheExchangeMutator;
@@ -63,12 +64,23 @@ public class ResponseCacheManager {
 
 	private final Cache cache;
 
-	public ResponseCacheManager(CacheKeyGenerator cacheKeyGenerator, Cache cache, Duration configuredTimeToLive) {
+	private final boolean ignoreNoCacheUpdate;
+
+	public ResponseCacheManager(CacheKeyGenerator cacheKeyGenerator, Cache cache, Duration configuredTimeToLive,
+			LocalResponseCacheRequestOptions requestOptions) {
 		this.cacheKeyGenerator = cacheKeyGenerator;
 		this.cache = cache;
+		this.ignoreNoCacheUpdate = isSkipNoCacheUpdateActive(requestOptions);
 		this.afterCacheExchangeMutators = List.of(new SetResponseHeadersAfterCacheExchangeMutator(),
 				new SetStatusCodeAfterCacheExchangeMutator(),
-				new SetMaxAgeHeaderAfterCacheExchangeMutator(configuredTimeToLive, Clock.systemDefaultZone()));
+				new SetMaxAgeHeaderAfterCacheExchangeMutator(configuredTimeToLive, Clock.systemDefaultZone(),
+						ignoreNoCacheUpdate),
+				new SetCacheDirectivesByMaxAgeAfterCacheExchangeMutator());
+	}
+
+	private static boolean isSkipNoCacheUpdateActive(LocalResponseCacheRequestOptions requestOptions) {
+		return Optional.ofNullable(requestOptions).map(LocalResponseCacheRequestOptions::getNoCache)
+				.filter(RequestNoCacheDirectiveStrategy.SKIP_UPDATE_CACHE_ENTRY::equals).isPresent();
 	}
 
 	private static final List<HttpStatusCode> statusesToCache = Arrays.asList(HttpStatus.OK, HttpStatus.PARTIAL_CONTENT,
@@ -132,13 +144,8 @@ public class ResponseCacheManager {
 		afterCacheExchangeMutators.forEach(processor -> processor.accept(exchange, cachedResponse));
 		saveMetadataInCache(metadataKey, new CachedResponseMetadata(cachedResponse.headers().getVary()));
 
-		if (HttpStatus.NOT_MODIFIED.equals(response.getStatusCode())) {
-			return response.writeWith(Mono.empty());
-		}
-		else {
-			return response.writeWith(
-					Flux.fromIterable(cachedResponse.body()).map(data -> response.bufferFactory().wrap(data)));
-		}
+		return response
+				.writeWith(Flux.fromIterable(cachedResponse.body()).map(data -> response.bufferFactory().wrap(data)));
 	}
 
 	private CachedResponseMetadata retrieveMetadata(String metadataKey) {
@@ -157,6 +164,10 @@ public class ResponseCacheManager {
 		return isStatusCodeToCache(response) && isCacheControlAllowed(response) && !isVaryWildcard(response);
 	}
 
+	boolean isNoCacheRequestWithoutUpdate(ServerHttpRequest request) {
+		return LocalResponseCacheUtils.isNoCacheRequest(request) && ignoreNoCacheUpdate;
+	}
+
 	private boolean isStatusCodeToCache(ServerHttpResponse response) {
 		return statusesToCache.contains(response.getStatusCode());
 	}

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/ResponseCacheManagerFactory.java

@@ -33,8 +33,9 @@ public class ResponseCacheManagerFactory {
 		this.cacheKeyGenerator = cacheKeyGenerator;
 	}
 
-	public ResponseCacheManager create(Cache cache, Duration timeToLive) {
-		return new ResponseCacheManager(cacheKeyGenerator, cache, timeToLive);
+	public ResponseCacheManager create(Cache cache, Duration timeToLive,
+			LocalResponseCacheRequestOptions requestOptions) {
+		return new ResponseCacheManager(cacheKeyGenerator, cache, timeToLive, requestOptions);
 	}
 
 }

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/postprocessor/SetCacheDirectivesByMaxAgeAfterCacheExchangeMutator.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2013-2020 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.cloud.gateway.filter.factory.cache.postprocessor;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+
+import org.springframework.cloud.gateway.filter.factory.cache.CachedResponse;
+import org.springframework.web.server.ServerWebExchange;
+
+public class SetCacheDirectivesByMaxAgeAfterCacheExchangeMutator implements AfterCacheExchangeMutator {
+
+	final Pattern MAX_AGE_PATTERN = Pattern.compile("(?:,|^)\\s*max-age=(\\d+)");
+
+	@Override
+	public void accept(ServerWebExchange exchange, CachedResponse cachedResponse) {
+		Optional<Integer> maxAge = Optional.ofNullable(exchange.getResponse().getHeaders().getCacheControl())
+				.map(MAX_AGE_PATTERN::matcher).filter(Matcher::find).map(matcher -> matcher.group(1))
+				.map(Integer::parseInt);
+
+		if (maxAge.isPresent()) {
+			if (maxAge.get() > 0) {
+				removeNoCacheHeaders(exchange);
+			}
+			else {
+				keepNoCacheHeaders(exchange);
+			}
+		}
+	}
+
+	private void keepNoCacheHeaders(ServerWebExchange exchange) {
+		// at least it contains 'max-age' so we can append items with commas safely
+		String cacheControl = exchange.getResponse().getHeaders().getCacheControl();
+		StringBuilder newCacheControl = new StringBuilder(cacheControl);
+
+		if (!cacheControl.contains("no-cache")) {
+			newCacheControl.append(",no-cache");
+		}
+
+		if (!cacheControl.contains("must-revalidate")) {
+			newCacheControl.append(",must-revalidate");
+		}
+		exchange.getResponse().getHeaders().setCacheControl(newCacheControl.toString());
+	}
+
+	private void removeNoCacheHeaders(ServerWebExchange exchange) {
+		String cacheControl = exchange.getResponse().getHeaders().getCacheControl();
+		List<String> cacheControlValues = Arrays.asList(cacheControl.split("\\s*,\\s*"));
+
+		String newCacheControl = cacheControlValues.stream()
+				.filter(s -> !s.matches("must-revalidate|no-cache|no-store")).collect(Collectors.joining(","));
+		exchange.getResponse().getHeaders().setCacheControl(newCacheControl);
+	}
+
+}

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/postprocessor/SetMaxAgeHeaderAfterCacheExchangeMutator.java

@@ -25,7 +25,9 @@ import java.util.List;
 import java.util.stream.Collectors;
 
 import org.springframework.cloud.gateway.filter.factory.cache.CachedResponse;
+import org.springframework.cloud.gateway.filter.factory.cache.LocalResponseCacheUtils;
 import org.springframework.http.HttpHeaders;
+import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.web.server.ServerWebExchange;
 
@@ -45,25 +47,33 @@ public class SetMaxAgeHeaderAfterCacheExchangeMutator implements AfterCacheExcha
 
 	private final Clock clock;
 
-	public SetMaxAgeHeaderAfterCacheExchangeMutator(Duration configuredTimeToLive, Clock clock) {
+	private final boolean ignoreNoCacheUpdate;
+
+	public SetMaxAgeHeaderAfterCacheExchangeMutator(Duration configuredTimeToLive, Clock clock,
+			boolean ignoreNoCacheUpdate) {
 		this.configuredTimeToLive = configuredTimeToLive;
 		this.clock = clock;
+		this.ignoreNoCacheUpdate = ignoreNoCacheUpdate;
 	}
 
 	@Override
 	public void accept(ServerWebExchange exchange, CachedResponse cachedResponse) {
 		ServerHttpResponse response = exchange.getResponse();
-		long calculatedMaxAgeInSeconds = calculateMaxAgeInSeconds(cachedResponse, configuredTimeToLive);
+		long calculatedMaxAgeInSeconds = calculateMaxAgeInSeconds(exchange.getRequest(), cachedResponse,
+				configuredTimeToLive);
 		rewriteCacheControlMaxAge(response.getHeaders(), calculatedMaxAgeInSeconds);
 	}
 
-	private long calculateMaxAgeInSeconds(CachedResponse cachedResponse, Duration configuredTimeToLive) {
+	private long calculateMaxAgeInSeconds(ServerHttpRequest request, CachedResponse cachedResponse,
+			Duration configuredTimeToLive) {
+		boolean noCache = LocalResponseCacheUtils.isNoCacheRequest(request);
 		long maxAge;
-		if (configuredTimeToLive.getSeconds() == -1) {
-			maxAge = -1;
+		if (noCache && ignoreNoCacheUpdate || configuredTimeToLive.getSeconds() < 0) {
+			maxAge = 0;
 		}
 		else {
-			maxAge = Math.max(0, configuredTimeToLive.minus(getElapsedTimeInSeconds(cachedResponse)).getSeconds());
+			long calculatedMaxAge = configuredTimeToLive.minus(getElapsedTimeInSeconds(cachedResponse)).getSeconds();
+			maxAge = Math.max(0, calculatedMaxAge);
 		}
 
 		return maxAge;
@@ -77,10 +87,10 @@ public class SetMaxAgeHeaderAfterCacheExchangeMutator implements AfterCacheExcha
 		boolean isMaxAgePresent = headers.getCacheControl() != null
 				&& headers.getCacheControl().contains(MAX_AGE_PREFIX);
 
+		List<String> newCacheControlDirectives = new ArrayList<>();
 		if (isMaxAgePresent) {
 			List<String> cacheControlHeaders = headers.get(HttpHeaders.CACHE_CONTROL);
 			cacheControlHeaders = cacheControlHeaders == null ? Collections.emptyList() : cacheControlHeaders;
-			List<String> replacedCacheControlHeaders = new ArrayList<>();
 			for (String value : cacheControlHeaders) {
 				if (value.contains(MAX_AGE_PREFIX)) {
 					if (seconds == -1) {
@@ -92,11 +102,17 @@ public class SetMaxAgeHeaderAfterCacheExchangeMutator implements AfterCacheExcha
 						value = value.replaceFirst("\\bmax-age=\\d+\\b", MAX_AGE_PREFIX + seconds);
 					}
 				}
-				replacedCacheControlHeaders.add(value);
+				newCacheControlDirectives.add(value);
 			}
-			headers.remove(HttpHeaders.CACHE_CONTROL);
-			headers.addAll(HttpHeaders.CACHE_CONTROL, replacedCacheControlHeaders);
 		}
+		else {
+			List<String> cacheControlHeaders = headers.get(HttpHeaders.CACHE_CONTROL);
+			newCacheControlDirectives = cacheControlHeaders == null ? new ArrayList<>()
+					: new ArrayList<>(cacheControlHeaders);
+			newCacheControlDirectives.add("max-age=" + seconds);
+		}
+		headers.remove(HttpHeaders.CACHE_CONTROL);
+		headers.addAll(HttpHeaders.CACHE_CONTROL, newCacheControlDirectives);
 	}
 
 }

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/factory/cache/postprocessor/SetStatusCodeAfterCacheExchangeMutator.java

@@ -17,38 +17,21 @@
 package org.springframework.cloud.gateway.filter.factory.cache.postprocessor;
 
 import org.springframework.cloud.gateway.filter.factory.cache.CachedResponse;
-import org.springframework.http.HttpHeaders;
-import org.springframework.http.HttpStatus;
 import org.springframework.http.server.reactive.ServerHttpResponse;
-import org.springframework.util.CollectionUtils;
 import org.springframework.web.server.ServerWebExchange;
 
 /**
- * It sets HTTP Status Code depending {@literal no-cache}
- * {@link HttpHeaders#CACHE_CONTROL} header.
+ * It sets HTTP Status Code.
  *
  * @author Marta Medio
  * @author Ignacio Lozano
  */
 public class SetStatusCodeAfterCacheExchangeMutator implements AfterCacheExchangeMutator {
 
-	private static final String NO_CACHE_VALUE = "no-cache";
-
 	@Override
 	public void accept(ServerWebExchange exchange, CachedResponse cachedResponse) {
-		HttpHeaders requestHeaders = exchange.getRequest().getHeaders();
 		ServerHttpResponse response = exchange.getResponse();
-
-		if (!CollectionUtils.isEmpty(cachedResponse.body()) && isRequestNoCache(requestHeaders)) {
-			response.setStatusCode(HttpStatus.NOT_MODIFIED);
-		}
-		else {
-			response.setStatusCode(cachedResponse.statusCode());
-		}
-	}
-
-	private boolean isRequestNoCache(HttpHeaders requestHeaders) {
-		return requestHeaders.getCacheControl() != null && requestHeaders.getCacheControl().contains(NO_CACHE_VALUE);
+		response.setStatusCode(cachedResponse.statusCode());
 	}
 
 }

spring-cloud-gateway-server/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -46,12 +46,13 @@
       "name": "spring.cloud.gateway.filter.local-response-cache.size",
       "type": "org.springframework.util.unit.DataSize",
       "description": "Maximum size of the cache to evict entries for this route (in KB, MB and GB).",
-      "defaultValue": "5m"
+      "defaultValue": "null"
     },
     {
       "name": "spring.cloud.gateway.filter.local-response-cache.time-to-live",
       "type": "java.time.Duration",
-      "description": "Time to expire a cache entry (expressed in s for seconds, m for minutes, and h for hours)."
+      "description": "Time to expire a cache entry (expressed in s for seconds, m for minutes, and h for hours).",
+      "defaultValue": "5m"
     },
     {
       "name": "spring.cloud.gateway.filter.dedupe-response-header.enabled",

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/factory/cache/LocalResponseCacheGatewayFilterFactoryTests.java

@@ -17,6 +17,7 @@
 package org.springframework.cloud.gateway.filter.factory.cache;
 
 import java.time.Duration;
+import java.time.Instant;
 import java.util.Map;
 import java.util.Objects;
 import java.util.UUID;
@@ -44,6 +45,7 @@ import org.springframework.util.StringUtils;
 import org.springframework.util.unit.DataSize;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.data.Offset.offset;
 
 /**
  * @author Ignacio Lozano
@@ -53,12 +55,23 @@ import static org.assertj.core.api.Assertions.assertThat;
 @ActiveProfiles(profiles = "local-cache-filter")
 public class LocalResponseCacheGatewayFilterFactoryTests extends BaseWebClientTests {
 
-	private static final String CUSTOM_HEADER = "X-Custom-Date";
+	private static final String CUSTOM_HEADER = "X-Custom-Header";
+
+	private static Long parseMaxAge(String cacheControlValue) {
+		if (StringUtils.hasText(cacheControlValue)) {
+			Pattern maxAgePattern = Pattern.compile("\\bmax-age=(\\d+)\\b");
+			Matcher matcher = maxAgePattern.matcher(cacheControlValue);
+			if (matcher.find()) {
+				return Long.parseLong(matcher.group(1));
+			}
+		}
+		return null;
+	}
 
 	@Nested
 	@SpringBootTest(properties = { "spring.cloud.gateway.filter.local-response-cache.enabled=true" },
 			webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
-	public class LocalResponseCacheUsingFilterParams extends BaseWebClientTests {
+	public class UsingFilterParams extends BaseWebClientTests {
 
 		@Test
 		void shouldNotCacheResponseWhenGetRequestHasBody() {
@@ -101,17 +114,18 @@ public class LocalResponseCacheGatewayFilterFactoryTests extends BaseWebClientTe
 		}
 
 		@Test
-		void shouldCacheAndReturnNotModifiedStatusWhenCacheControlIsNoCache() {
+		void shouldNotIncludeMustRevalidateNoStoreAndNoCacheDirectivesWhenMaxAgeIsPositive() {
 			String uri = "/" + UUID.randomUUID() + "/cache/headers";
 
-			testClient.get().uri(uri).header("Host", "www.localresponsecache.org").header(CUSTOM_HEADER, "1").exchange()
-					.expectBody().jsonPath("$.headers." + CUSTOM_HEADER);
+			var response = testClient.get().uri(uri).header("Host", "www.localresponsecache.org").exchange()
+					.expectBody().returnResult();
+			var maxAge = response.getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
 
-			testClient.get().uri(uri).header("Host", "www.localresponsecache.org").header(CUSTOM_HEADER, "2")
-					// Cache-Control asks to not return cached content because it is
-					// HttpHeaders.NotModified
-					.header(HttpHeaders.CACHE_CONTROL, CacheControl.noCache().getHeaderValue()).exchange()
-					.expectStatus().isNotModified().expectBody().isEmpty();
+			assertThat(maxAge).isGreaterThan(0L);
+			assertThat(response.getResponseHeaders().get(HttpHeaders.CACHE_CONTROL)).doesNotContain("no-store",
+					"must-revalidate", "no-cache");
 		}
 
 		@Test
@@ -163,11 +177,13 @@ public class LocalResponseCacheGatewayFilterFactoryTests extends BaseWebClientTe
 			String uri = "/" + UUID.randomUUID() + "/cache/headers";
 			Long maxAgeRequest1 = testClient.get().uri(uri).header("Host", "www.localresponsecache.org").exchange()
 					.expectBody().returnResult().getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
-					.map(this::parseMaxAge).filter(Objects::nonNull).findAny().orElse(null);
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
 			Thread.sleep(2000);
 			Long maxAgeRequest2 = testClient.get().uri(uri).header("Host", "www.localresponsecache.org").exchange()
 					.expectBody().returnResult().getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
-					.map(this::parseMaxAge).filter(Objects::nonNull).findAny().orElse(null);
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
 
 			assertThat(maxAgeRequest2).isLessThan(maxAgeRequest1);
 		}
@@ -213,17 +229,6 @@ public class LocalResponseCacheGatewayFilterFactoryTests extends BaseWebClientTe
 					.jsonPath("$.headers." + CUSTOM_HEADER, "2");
 		}
 
-		private Long parseMaxAge(String cacheControlValue) {
-			if (StringUtils.hasText(cacheControlValue)) {
-				Pattern maxAgePattern = Pattern.compile("\\bmax-age=(\\d+)\\b");
-				Matcher matcher = maxAgePattern.matcher(cacheControlValue);
-				if (matcher.find()) {
-					return Long.parseLong(matcher.group(1));
-				}
-			}
-			return null;
-		}
-
 		void assertNonVaryHeaderInContent(String uri, String varyHeader, String varyHeaderValue, String nonVaryHeader,
 				String nonVaryHeaderValue, String expectedNonVaryResponse) {
 			testClient.get().uri(uri).header("Host", "www.localresponsecache.org").header("X-Request-Vary", varyHeader)
@@ -275,34 +280,186 @@ public class LocalResponseCacheGatewayFilterFactoryTests extends BaseWebClientTe
 			properties = { "spring.cloud.gateway.filter.local-response-cache.enabled=true",
 					"spring.cloud.gateway.filter.local-response-cache.timeToLive=20s" },
 			webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
-	public class LocalResponseCacheUsingDefaultProperties extends BaseWebClientTests {
+	public class UsingPropertiesAsDefault extends BaseWebClientTests {
 
 		@Test
 		void shouldApplyMaxAgeFromPropertiesWhenFilterHasNoParams() throws InterruptedException {
 			String uri = "/" + UUID.randomUUID() + "/cache/headers";
 			Long maxAgeRequest1 = testClient.get().uri(uri).header("Host", "www.localresponsecache.org").exchange()
 					.expectBody().returnResult().getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
-					.map(this::parseMaxAge).filter(Objects::nonNull).findAny().orElse(null);
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
 			assertThat(maxAgeRequest1).isLessThanOrEqualTo(20L);
 
 			Thread.sleep(2000);
 
 			Long maxAgeRequest2 = testClient.get().uri(uri).header("Host", "www.localresponsecache.org").exchange()
 					.expectBody().returnResult().getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
-					.map(this::parseMaxAge).filter(Objects::nonNull).findAny().orElse(null);
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
 
 			assertThat(maxAgeRequest2).isLessThan(maxAgeRequest1);
 		}
 
-		private Long parseMaxAge(String cacheControlValue) {
-			if (StringUtils.hasText(cacheControlValue)) {
-				Pattern maxAgePattern = Pattern.compile("\\bmax-age=(\\d+)\\b");
-				Matcher matcher = maxAgePattern.matcher(cacheControlValue);
-				if (matcher.find()) {
-					return Long.parseLong(matcher.group(1));
-				}
+		@Test
+		void shouldNotCacheWhenPrivateDirectiveIsInRequest() {
+			testClient = testClient.mutate().responseTimeout(Duration.ofHours(1)).build();
+
+			String uri = "/" + UUID.randomUUID() + "/cache/headers";
+
+			testClient.get().uri(uri).header("Host", "www.localresponsecache.org")
+					.header(HttpHeaders.CACHE_CONTROL, CacheControl.noStore().getHeaderValue())
+					.header(CUSTOM_HEADER, "1").exchange().expectBody().jsonPath("$.headers." + CUSTOM_HEADER);
+
+			testClient.get().uri(uri).header("Host", "www.localresponsecache.org").header(CUSTOM_HEADER, "2").exchange()
+					.expectBody().jsonPath("$.headers." + CUSTOM_HEADER).isEqualTo("2");
+
+			testClient.get().uri(uri).header("Host", "www.localresponsecache.org").header(CUSTOM_HEADER, "3") // second
+																												// request
+																												// cached
+																												// "2"
+																												// ->
+																												// "3"
+																												// will
+																												// be
+																												// ignored
+					.exchange().expectBody().jsonPath("$.headers." + CUSTOM_HEADER).isEqualTo("2");
+		}
+
+		@EnableAutoConfiguration
+		@SpringBootConfiguration
+		@Import(DefaultTestConfig.class)
+		public static class TestConfig {
+
+			@Value("${test.uri}")
+			String uri;
+
+			@Bean
+			public RouteLocator testRouteLocator(RouteLocatorBuilder builder) {
+				return builder.routes().route("local_response_cache_java_test",
+						r -> r.path("/{namespace}/cache/**").and().host("{sub}.localresponsecache.org")
+								.filters(f -> f.stripPrefix(2).prefixPath("/httpbin").localResponseCache(null, null))
+								.uri(uri))
+						.build();
+			}
+
+		}
+
+	}
+
+	@Nested
+	@SpringBootTest(
+			properties = { "spring.cloud.gateway.filter.local-response-cache.enabled=true",
+					"spring.cloud.gateway.filter.local-response-cache.time-to-live=2m",
+					"spring.cloud.gateway.filter.local-response-cache.request.no-cache=skip-update-cache-entry" },
+			webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+	public class DirectiveNoCacheSkippingUpdate extends BaseWebClientTests {
+
+		@Test
+		void shouldNotCacheWhenCacheControlAsksToValidateWithNotCache_refreshCacheWhenDirectiveNoCache()
+				throws InterruptedException {
+			String uri = "/" + UUID.randomUUID() + "/cache/headers";
+
+			// 1. Store in cache - max-age ~= 2m AND NOT
+			// (must-revalidate,no-cache,no-store)
+			final Instant when1stRequest = Instant.now();
+			var firstResponse = testClient.get().uri(uri).header("Host", "www.localresponsecache.org")
+					.header(CUSTOM_HEADER, "1").exchange().expectBody().jsonPath("$.headers." + CUSTOM_HEADER)
+					.isEqualTo("1").returnResult();
+			var maxAge1st = firstResponse.getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
+			assertThat(maxAge1st).isCloseTo(Duration.ofMinutes(2).toSeconds(), offset(10L));
+			assertThat(firstResponse.getResponseHeaders().getCacheControl()).doesNotContain("must-revalidate",
+					"no-cache", "no-store");
+
+			// 2. "no-cache" should return max-age=0 & must-revalidate,no-cache,no-store
+			var secondResponse = testClient.get().uri(uri).header("Host", "www.localresponsecache.org")
+					.header(CUSTOM_HEADER, "2")
+					// Cache-Control asks to not use the cached content
+					.header(HttpHeaders.CACHE_CONTROL, CacheControl.noCache().getHeaderValue()).exchange().expectBody()
+					.jsonPath("$.headers." + CUSTOM_HEADER).isEqualTo("2").returnResult();
+			var maxAge2nd = secondResponse.getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
+			assertThat(maxAge2nd).isZero();
+
+			// 3. After 2s, max-age = (when1stRequest) - 1s - offset_delay
+			var waitDuration = Duration.ofSeconds(1);
+			Thread.sleep(waitDuration.toMillis()); // Wait 2s to check max-age renewed
+			final Instant when3rdRequest = Instant.now();
+			var thirdResponseCached = testClient.get().uri(uri).header("Host", "www.localresponsecache.org")
+					.header(CUSTOM_HEADER, "3").exchange().expectBody().jsonPath("$.headers." + CUSTOM_HEADER)
+					.isEqualTo("1").returnResult();
+			var maxAge3rd = thirdResponseCached.getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
+			assertThat(maxAge3rd).isCloseTo(
+					Duration.ofMinutes(2).minus(Duration.between(when1stRequest, when3rdRequest)).getSeconds(),
+					offset(10L));
+			assertThat(maxAge3rd).isNotZero();
+		}
+
+		@EnableAutoConfiguration
+		@SpringBootConfiguration
+		@Import(DefaultTestConfig.class)
+		public static class TestConfig {
+
+			@Value("${test.uri}")
+			String uri;
+
+			@Bean
+			public RouteLocator testRouteLocator(RouteLocatorBuilder builder) {
+				return builder.routes().route("local_response_cache_java_test",
+						r -> r.path("/{namespace}/cache/**").and().host("{sub}.localresponsecache.org")
+								.filters(f -> f.stripPrefix(2).prefixPath("/httpbin").localResponseCache(null, null))
+								.uri(uri))
+						.build();
 			}
-			return null;
+
+		}
+
+	}
+
+	@Nested
+	@SpringBootTest(
+			properties = { "spring.cloud.gateway.filter.local-response-cache.enabled=true",
+					"spring.cloud.gateway.filter.local-response-cache.time-to-live=2m",
+					"spring.cloud.gateway.filter.local-response-cache.request.no-cache=update-cache-entry" },
+			webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+	public class DirectiveNoCacheWithUpdate extends BaseWebClientTests {
+
+		@Test
+		void oldMaxAgeWhenNoCacheRequest() throws InterruptedException {
+			testClient = testClient.mutate().responseTimeout(Duration.ofHours(1)).build();
+
+			String uri = "/" + UUID.randomUUID() + "/cache/headers";
+			// First request -> cache miss
+			final Instant when1stRequest = Instant.now();
+			Long maxAgeRequest1 = testClient.get().uri(uri).header("Host", "www.localresponsecache.org").exchange()
+					.expectBody().returnResult().getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
+			assertThat(maxAgeRequest1).isCloseTo(Duration.ofMinutes(2).toSeconds(), offset(10L));
+
+			// Second request + no-cache -> skip cache and ignore update
+			Thread.sleep(1000);
+			final Duration between1stAnd2ndRequest = Duration.between(when1stRequest, Instant.now());
+			Long maxAgeRequest2 = testClient.get().uri(uri).header("Host", "www.localresponsecache.org")
+					.header(HttpHeaders.CACHE_CONTROL, CacheControl.noCache().getHeaderValue()).exchange().expectBody()
+					.returnResult().getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
+			assertThat(maxAgeRequest2).isCloseTo(Duration.ofMinutes(2).minus(between1stAnd2ndRequest).getSeconds(),
+					offset(10L));
+
+			// Third request -> cache hit -> entry (and max-age) is updated
+			Thread.sleep(1000);
+			Long maxAgeRequest3 = testClient.get().uri(uri).header("Host", "www.localresponsecache.org").exchange()
+					.expectBody().returnResult().getResponseHeaders().get(HttpHeaders.CACHE_CONTROL).stream()
+					.map(LocalResponseCacheGatewayFilterFactoryTests::parseMaxAge).filter(Objects::nonNull).findAny()
+					.orElse(null);
+			assertThat(maxAgeRequest3).isCloseTo(Duration.ofMinutes(2).toSeconds(), offset(10L));
 		}
 
 		@EnableAutoConfiguration

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/factory/cache/LocalResponseCacheUtilsTests.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2013-2020 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.cloud.gateway.filter.factory.cache;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class LocalResponseCacheUtilsTests {
+
+	@ParameterizedTest
+	@ValueSource(strings = { "", "no-store", "no-store, wrong-no-cache", "s-no-cache" })
+	void shouldNotIdentifyRequestAsNoCacheRequest(String cacheControl) {
+		MockServerHttpRequest httpRequest = MockServerHttpRequest.get("https://this")
+				.header("Cache-Control", cacheControl).build();
+
+		boolean result = LocalResponseCacheUtils.isNoCacheRequest(httpRequest);
+
+		assertThat(result).isFalse();
+	}
+
+	@ParameterizedTest
+	@ValueSource(strings = { "no-cache", "s-no-cache, no-cache", "private,no-cache", " no-cache", "no-cache " })
+	void shouldIdentifyRequestAsNoCacheRequest(String cacheControl) {
+		MockServerHttpRequest httpRequest = MockServerHttpRequest.get("https://this")
+				.header("Cache-Control", cacheControl).build();
+
+		boolean result = LocalResponseCacheUtils.isNoCacheRequest(httpRequest);
+
+		assertThat(result).isTrue();
+	}
+
+}

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/factory/cache/ResponseCacheGatewayFilterTest.java

@@ -30,7 +30,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class ResponseCacheGatewayFilterTest {
 
-	ResponseCacheManager cacheManagerToTest = new ResponseCacheManager(null, null, null);
+	ResponseCacheManager cacheManagerToTest = new ResponseCacheManager(null, null, null, null);
 
 	@Test
 	void requestShouldBeCacheable() {

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/factory/cache/postprocessor/SetCacheDirectivesByMaxAgeAfterCacheExchangeMutatorTests.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2013-2020 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.cloud.gateway.filter.factory.cache.postprocessor;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+import org.springframework.mock.http.server.reactive.MockServerHttpResponse;
+import org.springframework.mock.web.server.MockServerWebExchange;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class SetCacheDirectivesByMaxAgeAfterCacheExchangeMutatorTests {
+
+	private MockServerWebExchange inputExchange;
+
+	private SetCacheDirectivesByMaxAgeAfterCacheExchangeMutator toTest;
+
+	@BeforeEach
+	void setUp() {
+		HttpHeaders responseHeaders = new HttpHeaders();
+		responseHeaders.setCacheControl("max-age=1234");
+		MockServerHttpRequest httpRequest = MockServerHttpRequest.get("https://this").build();
+
+		inputExchange = MockServerWebExchange.from(httpRequest);
+		MockServerHttpResponse httpResponse = inputExchange.getResponse();
+		httpResponse.setStatusCode(HttpStatus.OK);
+		httpResponse.getHeaders().putAll(responseHeaders);
+
+		toTest = new SetCacheDirectivesByMaxAgeAfterCacheExchangeMutator();
+	}
+
+	@ParameterizedTest
+	@ValueSource(strings = { "", "ETag=1234-123", "s-max-age=20" })
+	void doesntModifyCacheControlWhenNoMaxAge(String cacheControlValue) {
+		inputExchange.getResponse().getHeaders().setCacheControl(cacheControlValue);
+
+		toTest.accept(inputExchange, null);
+
+		assertThat(inputExchange.getResponse().getHeaders().getCacheControl()).isEqualTo(cacheControlValue);
+	}
+
+	@ParameterizedTest
+	@ValueSource(
+			strings = { "max-age=0", "ETag=1234-123,max-age=0", "s-max-age=20,max-age=0", "ETag=with-spaces, max-age=0",
+					"ETag=with-spaces, max-age=0,Expires=123123123", " max-age=0, ETag=with-spaces" })
+	void directivesNoCacheAreAddedWhenMaxAgeIsZero(String cacheControlValue) {
+		inputExchange.getResponse().getHeaders().setCacheControl(cacheControlValue);
+
+		toTest.accept(inputExchange, null);
+
+		assertThat(inputExchange.getResponse().getHeaders().getCacheControl()).doesNotContainPattern(",\\s*,")
+				.contains("max-age=0").contains("must-revalidate").contains("no-cache");
+	}
+
+	@ParameterizedTest
+	@ValueSource(strings = { "max-age=10,must-revalidate", "must-revalidate,ETag=1234-123,max-age=10",
+			"must-revalidate,s-max-age=0,max-age=10", " max-age=10, must-revalidate,ETag=with-spaces",
+			"ETag=with-spaces,must-revalidate, max-age=10,Expires=123123123",
+			"ETag=with-spaces,must-revalidate, max-age=10", "max-age=10,no-store" })
+	void directivesNoCacheAreRemovedWhenMaxAgePositive(String cacheControlValue) {
+		inputExchange.getResponse().getHeaders().setCacheControl(cacheControlValue);
+
+		toTest.accept(inputExchange, null);
+
+		assertThat(inputExchange.getResponse().getHeaders().getCacheControl()).contains("max-age=10")
+				.doesNotContainPattern(",\\s*,").doesNotContain("no-store").doesNotContain("must-revalidate")
+				.doesNotContain("no-cache");
+	}
+
+}

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/factory/cache/postprocessor/SetMaxAgeHeaderAfterCacheExchangeMutatorTest.java

@@ -34,7 +34,7 @@ import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
 import org.springframework.mock.http.server.reactive.MockServerHttpResponse;
 import org.springframework.mock.web.server.MockServerWebExchange;
-import org.springframework.util.StringUtils;
+import org.springframework.util.CollectionUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -67,16 +67,29 @@ class SetMaxAgeHeaderAfterCacheExchangeMutatorTest {
 	}
 
 	@Test
-	void maxAgeIsNotAdded_whenMaxAgeIsNotPresent() {
+	void maxAgeIsTimeToLive_whenMaxAgeIsNotPresent() {
 		inputExchange.getResponse().getHeaders().setCacheControl((String) null);
 
 		Duration timeToLive = Duration.ofSeconds(30);
 		CachedResponse inputCachedResponse = CachedResponse.create(HttpStatus.OK).timestamp(clock.instant()).build();
 
 		SetMaxAgeHeaderAfterCacheExchangeMutator toTest = new SetMaxAgeHeaderAfterCacheExchangeMutator(timeToLive,
-				clock);
+				clock, false);
 		toTest.accept(inputExchange, inputCachedResponse);
-		assertThat(parseMaxAge(inputExchange.getResponse())).isEmpty();
+		assertThat(parseMaxAge(inputExchange.getResponse()).get()).isEqualTo(timeToLive.getSeconds());
+	}
+
+	@Test
+	void maxAgeIsZero_whenTimeToLiveIsNegative() {
+		inputExchange.getResponse().getHeaders().setCacheControl((String) null);
+
+		Duration timeToLive = Duration.ofSeconds(-1);
+		CachedResponse inputCachedResponse = CachedResponse.create(HttpStatus.OK).timestamp(clock.instant()).build();
+
+		SetMaxAgeHeaderAfterCacheExchangeMutator toTest = new SetMaxAgeHeaderAfterCacheExchangeMutator(timeToLive,
+				clock, false);
+		toTest.accept(inputExchange, inputCachedResponse);
+		assertThat(parseMaxAge(inputExchange.getResponse()).get()).isEqualTo(0L);
 	}
 
 	@Test
@@ -85,12 +98,12 @@ class SetMaxAgeHeaderAfterCacheExchangeMutatorTest {
 		CachedResponse inputCachedResponse = CachedResponse.create(HttpStatus.OK).timestamp(clock.instant()).build();
 
 		SetMaxAgeHeaderAfterCacheExchangeMutator toTest = new SetMaxAgeHeaderAfterCacheExchangeMutator(timeToLive,
-				clock);
+				clock, false);
 		toTest.accept(inputExchange, inputCachedResponse);
 		Optional<Long> firstMaxAgeSeconds = parseMaxAge(inputExchange.getResponse());
 
 		SetMaxAgeHeaderAfterCacheExchangeMutator toTestSecondsLater = new SetMaxAgeHeaderAfterCacheExchangeMutator(
-				timeToLive, clockSecondsLater);
+				timeToLive, clockSecondsLater, false);
 		toTestSecondsLater.accept(inputExchange, inputCachedResponse);
 		Optional<Long> secondMaxAgeSeconds = parseMaxAge(inputExchange.getResponse());
 
@@ -106,12 +119,12 @@ class SetMaxAgeHeaderAfterCacheExchangeMutatorTest {
 		CachedResponse inputCachedResponse = CachedResponse.create(HttpStatus.OK).timestamp(clock.instant()).build();
 
 		SetMaxAgeHeaderAfterCacheExchangeMutator toTest = new SetMaxAgeHeaderAfterCacheExchangeMutator(timeToLive,
-				clock);
+				clock, false);
 		toTest.accept(inputExchange, inputCachedResponse);
 		Optional<Long> firstMaxAgeSeconds = parseMaxAge(inputExchange.getResponse());
 
 		SetMaxAgeHeaderAfterCacheExchangeMutator toTestSecondsLater = new SetMaxAgeHeaderAfterCacheExchangeMutator(
-				timeToLive, clockSecondsLater);
+				timeToLive, clockSecondsLater, false);
 		toTestSecondsLater.accept(inputExchange, inputCachedResponse);
 		Optional<Long> secondMaxAgeSeconds = parseMaxAge(inputExchange.getResponse());
 
@@ -126,7 +139,7 @@ class SetMaxAgeHeaderAfterCacheExchangeMutatorTest {
 		CachedResponse inputCachedResponse = CachedResponse.create(HttpStatus.OK).timestamp(clock.instant()).build();
 
 		SetMaxAgeHeaderAfterCacheExchangeMutator toTest = new SetMaxAgeHeaderAfterCacheExchangeMutator(timeToLive,
-				clock);
+				clock, false);
 		toTest.accept(inputExchange, inputCachedResponse);
 
 		String[] cacheControlValues = Optional.ofNullable(inputExchange.getResponse().getHeaders().getCacheControl())
@@ -141,7 +154,7 @@ class SetMaxAgeHeaderAfterCacheExchangeMutatorTest {
 		CachedResponse inputCachedResponse = CachedResponse.create(HttpStatus.OK).timestamp(clock.instant()).build();
 
 		SetMaxAgeHeaderAfterCacheExchangeMutator toTest = new SetMaxAgeHeaderAfterCacheExchangeMutator(timeToLive,
-				clock);
+				clock, false);
 		toTest.accept(inputExchange, inputCachedResponse);
 
 		List<String> cacheControlValues = inputExchange.getResponse().getHeaders().get("X-Custom-Header");
@@ -149,18 +162,22 @@ class SetMaxAgeHeaderAfterCacheExchangeMutatorTest {
 	}
 
 	private Optional<Long> parseMaxAge(ServerHttpResponse response) {
-		return parseMaxAge(response.getHeaders().getCacheControl());
+		return parseMaxAge(response.getHeaders().get("Cache-Control"));
 	}
 
-	private Optional<Long> parseMaxAge(String cacheControlValue) {
-		if (StringUtils.hasText(cacheControlValue)) {
-			Pattern maxAgePattern = Pattern.compile("\\bmax-age=(\\d+)\\b");
-			Matcher matcher = maxAgePattern.matcher(cacheControlValue);
+	private Optional<Long> parseMaxAge(List<String> cacheControlValues) {
+		if (CollectionUtils.isEmpty(cacheControlValues)) {
+			return Optional.empty();
+		}
+
+		final Pattern maxAgePattern = Pattern.compile("\\bmax-age=(\\d+)\\b");
+		return cacheControlValues.stream().map(cacheControlDirective -> {
+			Matcher matcher = maxAgePattern.matcher(cacheControlDirective);
 			if (matcher.find()) {
-				return Optional.of(Long.parseLong(matcher.group(1)));
+				return Long.parseLong(matcher.group(1));
 			}
-		}
-		return Optional.empty();
+			return null;
+		}).filter(maxAge -> maxAge != null).findFirst();
 	}
 
 }

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/factory/cache/postprocessor/SetStatusCodeAfterCacheExchangeMutatorTest.java

@@ -17,7 +17,8 @@
 package org.springframework.cloud.gateway.filter.factory.cache.postprocessor;
 
 import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 
 import org.springframework.cloud.gateway.filter.factory.cache.CachedResponse;
 import org.springframework.http.HttpHeaders;
@@ -47,42 +48,17 @@ class SetStatusCodeAfterCacheExchangeMutatorTest {
 		httpResponse.getHeaders().putAll(responseHeaders);
 	}
 
-	@Test
-	void statusCodeIs304_whenCacheHitsAndNoCacheHeaderIsPresent() {
-		CachedResponse cachedResponse = CachedResponse.create(HttpStatus.OK).body("some-data").build();
-		MockServerHttpRequest httpRequest = MockServerHttpRequest.get("https://this")
-				.header("Cache-Control", "no-cache").build();
-
-		inputExchange = MockServerWebExchange.from(httpRequest);
-
-		SetStatusCodeAfterCacheExchangeMutator toTest = new SetStatusCodeAfterCacheExchangeMutator();
-		toTest.accept(inputExchange, cachedResponse);
-
-		assertThat(inputExchange.getResponse().getStatusCode()).isEqualTo(HttpStatus.NOT_MODIFIED);
-	}
-
-	@Test
-	void statusCodeIs200_whenCacheHitsAndNoCacheHeaderIsNotPresent() {
-		CachedResponse cachedResponse = CachedResponse.create(HttpStatus.OK).body("some-data").build();
-
-		SetStatusCodeAfterCacheExchangeMutator toTest = new SetStatusCodeAfterCacheExchangeMutator();
-		toTest.accept(inputExchange, cachedResponse);
-
-		assertThat(inputExchange.getResponse().getStatusCode()).isEqualTo(HttpStatus.OK);
-	}
-
-	@Test
-	void statusCodeIs200_whenNoCacheHitsAndEvenNoCacheHeaderIsPresent() {
-		CachedResponse cachedResponse = CachedResponse.create(HttpStatus.OK).build();
-		MockServerHttpRequest httpRequest = MockServerHttpRequest.get("https://this")
-				.header("Cache-Control", "no-cache").build();
+	@ParameterizedTest
+	@ValueSource(ints = {200, 400, 404, 500})
+	void statusCodeIsSetFromCachedResponse(int statusCode) {
+		CachedResponse cachedResponse = CachedResponse.create(HttpStatus.valueOf(statusCode)).body("some-data").build();
+		MockServerHttpRequest httpRequest = MockServerHttpRequest.get("https://this").build();
 
 		inputExchange = MockServerWebExchange.from(httpRequest);
 
 		SetStatusCodeAfterCacheExchangeMutator toTest = new SetStatusCodeAfterCacheExchangeMutator();
 		toTest.accept(inputExchange, cachedResponse);
 
-		assertThat(inputExchange.getResponse().getStatusCode()).isEqualTo(HttpStatus.OK);
+		assertThat(inputExchange.getResponse().getStatusCode()).isEqualTo(HttpStatus.valueOf(statusCode));
 	}
-
 }