Add support for useRelativeRedirects customization

Closes gh-10597

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

@@ -600,6 +600,12 @@ public class ServerProperties {
 		 */
 		private Boolean redirectContextRoot;
 
+		/**
+		 * Whether HTTP 1.1 and later location headers generated by a call to sendRedirect
+		 * will use relative or absolute redirects.
+		 */
+		private Boolean useRelativeRedirects;
+
 		/**
 		 * Character encoding to use to decode the URI.
 		 */
@@ -714,6 +720,14 @@ public class ServerProperties {
 			this.redirectContextRoot = redirectContextRoot;
 		}
 
+		public Boolean getUseRelativeRedirects() {
+			return this.useRelativeRedirects;
+		}
+
+		public void setUseRelativeRedirects(Boolean useRelativeRedirects) {
+			this.useRelativeRedirects = useRelativeRedirects;
+		}
+
 		public String getRemoteIpHeader() {
 			return this.remoteIpHeader;
 		}

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

@@ -256,6 +256,10 @@ public class DefaultServletWebServerFactoryCustomizer
 				customizeRedirectContextRoot(factory,
 						tomcatProperties.getRedirectContextRoot());
 			}
+			if (tomcatProperties.getUseRelativeRedirects() != null) {
+				customizeUseRelativeRedirects(factory,
+						tomcatProperties.getUseRelativeRedirects());
+			}
 			if (tomcatProperties.getMaxConnections() > 0) {
 				customizeMaxConnections(factory, tomcatProperties.getMaxConnections());
 			}
@@ -392,6 +396,13 @@ public class DefaultServletWebServerFactoryCustomizer
 					.setMapperContextRootRedirectEnabled(redirectContextRoot));
 		}
 
+		private static void customizeUseRelativeRedirects(
+				TomcatServletWebServerFactory factory,
+				final boolean useRelativeRedirects) {
+			factory.addContextCustomizers((context) -> context
+					.setUseRelativeRedirects(useRelativeRedirects));
+		}
+
 		private static void customizeStaticResources(Resource resource,
 				TomcatServletWebServerFactory factory) {
 			if (resource.getCacheTtl() == null) {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/DefaultServletWebServerFactoryCustomizerTests.java

@@ -168,6 +168,22 @@ public class DefaultServletWebServerFactoryCustomizerTests {
 		verify(context).setMapperContextRootRedirectEnabled(false);
 	}
 
+	@Test
+	public void useRelativeRedirectsCanBeConfigured() {
+		Map<String, String> map = new HashMap<>();
+		map.put("server.tomcat.use-relative-redirects", "true");
+		bindProperties(map);
+		ServerProperties.Tomcat tomcat = this.properties.getTomcat();
+		assertThat(tomcat.getUseRelativeRedirects()).isTrue();
+		TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory();
+		this.customizer.customize(factory);
+		Context context = mock(Context.class);
+		for (TomcatContextCustomizer customizer : factory.getTomcatContextCustomizers()) {
+			customizer.customize(context);
+		}
+		verify(context).setUseRelativeRedirects(true);
+	}
+
 	@Test
 	public void testCustomizeTomcat() throws Exception {
 		ConfigurableServletWebServerFactory factory = mock(

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

@@ -254,6 +254,7 @@ content into your application. Rather, pick only the properties that you need.
 	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.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.
 	server.undertow.accesslog.dir= # Undertow access log directory.
 	server.undertow.accesslog.enabled=false # Whether to enable the access log.
 	server.undertow.accesslog.pattern=common # Format pattern for access logs.