Add auto-configuration support for Spring Session

This commit adds support for automatically configuring Spring Session.
In a web application when both Spring Session and Spring Data Redis
are on the classpath, Spring Session's Redis Http Session support
will be auto-configured. The max inactive interval for Redis-backed
sessions can be configured via the environment using the existing
server.session-timeout property.

Closes gh-2318

spring-boot-samples/spring-boot-sample-session-redis/src/test/java/sample/session/redis/SampleSessionRedisApplicationTests.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2012-2015 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
+ *
+ *      http://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 sample.session.redis;
+
+import java.net.URI;
+
+import org.junit.Test;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.context.web.ServerPortInfoApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.data.redis.RedisConnectionFailureException;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.RequestEntity;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.client.RestTemplate;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Tests for {@link SampleSessionRedisApplication}.
+ *
+ * @author Andy Wilkinson
+ */
+public class SampleSessionRedisApplicationTests {
+
+	@Test
+	public void sessionExpiry() throws Exception {
+
+		String port = null;
+
+		try {
+			ConfigurableApplicationContext context = new SpringApplicationBuilder()
+					.sources(SampleSessionRedisApplication.class)
+					.properties("server.port:0")
+					.initializers(new ServerPortInfoApplicationContextInitializer())
+					.run();
+			port = context.getEnvironment().getProperty("local.server.port");
+		}
+		catch (RuntimeException ex) {
+			if (!redisServerRunning(ex)) {
+				return;
+			}
+		}
+
+		URI uri = URI.create("http://localhost:" + port + "/");
+		RestTemplate restTemplate = new RestTemplate();
+
+		ResponseEntity<String> response = restTemplate.getForEntity(uri, String.class);
+		String uuid1 = response.getBody();
+		HttpHeaders requestHeaders = new HttpHeaders();
+		requestHeaders.set("Cookie", response.getHeaders().getFirst("Set-Cookie"));
+
+		RequestEntity<Void> request = new RequestEntity<Void>(requestHeaders,
+				HttpMethod.GET, uri);
+
+		String uuid2 = restTemplate.exchange(request, String.class).getBody();
+		assertThat(uuid1, is(equalTo(uuid2)));
+
+		Thread.sleep(5000);
+
+		String uuid3 = restTemplate.exchange(request, String.class).getBody();
+		assertThat(uuid2, is(not(equalTo(uuid3))));
+	}
+
+	private boolean redisServerRunning(Throwable ex) {
+		if (ex instanceof RedisConnectionFailureException) {
+			return false;
+		}
+		return (ex.getCause() == null || redisServerRunning(ex.getCause()));
+	}
+
+}