Merge pull request #13614 from chtompki:issue-13613

* pr/13614:
  Polish "Add configuration for Tomcat's cachingAllowed property"
  Add configuration for Tomcat's cachingAllowed property

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ServerProperties.java

@@ -660,11 +660,24 @@ public class ServerProperties {
 		 */
 		public static class Resource {
 
+			/**
+			 * Whether static resource caching is permitted for this web application.
+			 */
+			private boolean allowCaching = true;
+
 			/**
 			 * Time-to-live of the static resource cache.
 			 */
 			private Duration cacheTtl;
 
+			public boolean isAllowCaching() {
+				return this.allowCaching;
+			}
+
+			public void setAllowCaching(boolean allowCaching) {
+				this.allowCaching = allowCaching;
+			}
+
 			public Duration getCacheTtl() {
 				return this.cacheTtl;
 			}

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/embedded/TomcatWebServerFactoryCustomizer.java

@@ -241,14 +241,14 @@ public class TomcatWebServerFactoryCustomizer implements
 	private void customizeStaticResources(ConfigurableTomcatWebServerFactory factory) {
 		ServerProperties.Tomcat.Resource resource = this.serverProperties.getTomcat()
 				.getResource();
-		if (resource.getCacheTtl() == null) {
-			return;
-		}
 		factory.addContextCustomizers((context) -> {
 			context.addLifecycleListener((event) -> {
 				if (event.getType().equals(Lifecycle.CONFIGURE_START_EVENT)) {
-					long ttl = resource.getCacheTtl().toMillis();
+					context.getResources().setCachingAllowed(resource.isAllowCaching());
-					context.getResources().setCacheTtl(ttl);
+					if (resource.getCacheTtl() != null) {
+						long ttl = resource.getCacheTtl().toMillis();
+						context.getResources().setCacheTtl(ttl);
+					}
 				}
 			});
 		});

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/embedded/TomcatWebServerFactoryCustomizerTests.java

@@ -16,14 +16,17 @@
 
 package org.springframework.boot.autoconfigure.web.embedded;
 
+import java.util.Map;
 import java.util.function.Consumer;
 
 import org.apache.catalina.Context;
 import org.apache.catalina.Valve;
+import org.apache.catalina.mapper.Mapper;
 import org.apache.catalina.startup.Tomcat;
 import org.apache.catalina.valves.AccessLogValve;
 import org.apache.catalina.valves.ErrorReportValve;
 import org.apache.catalina.valves.RemoteIpValve;
+import org.apache.catalina.webresources.StandardRoot;
 import org.apache.coyote.AbstractProtocol;
 import org.junit.Before;
 import org.junit.Test;
@@ -36,6 +39,7 @@ import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactor
 import org.springframework.boot.web.embedded.tomcat.TomcatWebServer;
 import org.springframework.mock.env.MockEnvironment;
 import org.springframework.test.context.support.TestPropertySourceUtils;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -44,6 +48,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Brian Clozel
  * @author Phillip Webb
+ * @author Rob Tompkins
  */
 public class TomcatWebServerFactoryCustomizerTests {
 
@@ -121,6 +126,20 @@ public class TomcatWebServerFactoryCustomizerTests {
 		assertThat(remoteIpValve.getInternalProxies()).isEqualTo("192.168.0.1");
 	}
 
+	@Test
+	public void customStaticResourceAllowCaching() {
+		bind("server.tomcat.resource.allow-caching=false");
+		customizeAndRunServer((server) -> {
+			Mapper mapper = server.getTomcat().getService().getMapper();
+			Object contextObjectToContextVersionMap = ReflectionTestUtils.getField(mapper,
+					"contextObjectToContextVersionMap");
+			Object tomcatEmbeddedContext = ((Map<Context, Object>) contextObjectToContextVersionMap)
+					.values().toArray()[0];
+			assertThat(((StandardRoot) ReflectionTestUtils.getField(tomcatEmbeddedContext,
+					"resources")).isCachingAllowed()).isFalse();
+		});
+	}
+
 	@Test
 	public void customStaticResourceCacheTtl() {
 		bind("server.tomcat.resource.cache-ttl=10000");

spring-boot-project/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -259,6 +259,7 @@ content into your application. Rather, pick only the properties that you need.
 	server.tomcat.protocol-header-https-value=https # Value of the protocol header indicating whether the incoming request uses SSL.
 	server.tomcat.redirect-context-root= # Whether requests to the context root should be redirected by appending a / to the path.
 	server.tomcat.remote-ip-header= # Name of the HTTP header from which the remote IP is extracted. For instance, `X-FORWARDED-FOR`.
+	server.tomcat.resource.allow-caching= # Whether static resource caching is permitted for this web application.
 	server.tomcat.resource.cache-ttl= # Time-to-live of the static resource cache.
 	server.tomcat.uri-encoding=UTF-8 # Character encoding to use to decode the URI.
 	server.tomcat.use-relative-redirects= # Whether HTTP 1.1 and later location headers generated by a call to sendRedirect will use relative or absolute redirects.