Improve DefaultCookieSerializer auto-configuration

Spring Session's own configuration support (i.e.
SpringHttpSessionConfiguration) will configure the default
DefaultCookieSerializer with rememberMeRequestAttribute if
SpringSessionRememberMeServices bean has been detected in the
application context.

In contrast, Spring Boot's auto-configured DefaultCookieSerializer does
not do this which results in a different out-of-the-box experience for
users that rely on Spring Session's remember-me integration.

This commit improves Spring Session DefaultCookieSerializer
auto-configuration to match Spring Session's behavior and make the
auto-configured DefaultCookieSerializer aware of
SpringSessionRememberMeServices bean.

See gh-16513

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/session/SessionAutoConfiguration.java

@@ -56,6 +56,7 @@ import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.session.ReactiveSessionRepository;
 import org.springframework.session.Session;
 import org.springframework.session.SessionRepository;
+import org.springframework.session.security.web.authentication.SpringSessionRememberMeServices;
 import org.springframework.session.web.http.CookieHttpSessionIdResolver;
 import org.springframework.session.web.http.CookieSerializer;
 import org.springframework.session.web.http.DefaultCookieSerializer;
@@ -89,6 +90,14 @@ public class SessionAutoConfiguration {
 			SessionRepositoryFilterConfiguration.class })
 	static class ServletSessionConfiguration {
 
+		private final SpringSessionRememberMeServices springSessionRememberMeServices;
+
+		ServletSessionConfiguration(
+				ObjectProvider<SpringSessionRememberMeServices> springSessionRememberMeServices) {
+			this.springSessionRememberMeServices = springSessionRememberMeServices
+					.getIfAvailable();
+		}
+
 		@Bean
 		@Conditional(DefaultCookieSerializerCondition.class)
 		public DefaultCookieSerializer cookieSerializer(
@@ -103,6 +112,10 @@ public class SessionAutoConfiguration {
 			map.from(cookie::getSecure).to(cookieSerializer::setUseSecureCookie);
 			map.from(cookie::getMaxAge).to((maxAge) -> cookieSerializer
 					.setCookieMaxAge((int) maxAge.getSeconds()));
+			if (this.springSessionRememberMeServices != null) {
+				cookieSerializer.setRememberMeRequestAttribute(
+						SpringSessionRememberMeServices.REMEMBER_ME_LOGIN_ATTR);
+			}
 			return cookieSerializer;
 		}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/session/SessionAutoConfigurationTests.java

@@ -34,6 +34,7 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.session.MapSessionRepository;
 import org.springframework.session.SessionRepository;
 import org.springframework.session.config.annotation.web.http.EnableSpringHttpSession;
+import org.springframework.session.security.web.authentication.SpringSessionRememberMeServices;
 import org.springframework.session.web.http.CookieHttpSessionIdResolver;
 import org.springframework.session.web.http.DefaultCookieSerializer;
 import org.springframework.session.web.http.HeaderHttpSessionIdResolver;
@@ -245,6 +246,19 @@ public class SessionAutoConfigurationTests extends AbstractSessionAutoConfigurat
 						context.getBeansOfType(DefaultCookieSerializer.class)).isEmpty());
 	}
 
+	@Test
+	public void autoConfiguredCookieSerializerIsConfiguredWithRememberMeRequestAttribute() {
+		this.contextRunner
+				.withUserConfiguration(SpringSessionRememberMeServicesConfiguration.class)
+				.run((context) -> {
+					DefaultCookieSerializer cookieSerializer = context
+							.getBean(DefaultCookieSerializer.class);
+					assertThat(cookieSerializer).hasFieldOrPropertyWithValue(
+							"rememberMeRequestAttribute",
+							SpringSessionRememberMeServices.REMEMBER_ME_LOGIN_ATTR);
+				});
+	}
+
 	@Configuration
 	@EnableSpringHttpSession
 	static class SessionRepositoryConfiguration {
@@ -309,4 +323,16 @@ public class SessionAutoConfigurationTests extends AbstractSessionAutoConfigurat
 
 	}
 
+	@Configuration
+	@EnableSpringHttpSession
+	static class SpringSessionRememberMeServicesConfiguration
+			extends SessionRepositoryConfiguration {
+
+		@Bean
+		public SpringSessionRememberMeServices rememberMeServices() {
+			return new SpringSessionRememberMeServices();
+		}
+
+	}
+
 }