Make `spring.session.store-type` mandatory

This commit removes the automatic enabling of Redis as the Spring Session
store when it is available. This case is covered by a warning in `1.4.x`
that this commit removes as well.

Closes gh-7858

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

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -16,11 +16,6 @@
 
 package org.springframework.boot.autoconfigure.session;
 
-import javax.annotation.PostConstruct;
-
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -45,8 +40,6 @@ import org.springframework.session.data.redis.config.annotation.web.http.RedisHt
 @Conditional(SessionCondition.class)
 class RedisSessionConfiguration {
 
-	private static final Log logger = LogFactory.getLog(RedisSessionConfiguration.class);
-
 	@Configuration
 	public static class SpringBootRedisHttpSessionConfiguration
 			extends RedisHttpSessionConfiguration {
@@ -65,14 +58,6 @@ class RedisSessionConfiguration {
 			setRedisFlushMode(redis.getFlushMode());
 		}
 
-		@PostConstruct
-		public void validate() {
-			if (this.sessionProperties.getStoreType() == null) {
-				logger.warn("Spring Session store type is mandatory: set "
-						+ "'spring.session.store-type=redis' in your configuration");
-			}
-		}
-
 	}
 
 }

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

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -23,19 +23,15 @@ import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.context.annotation.ConditionContext;
 import org.springframework.core.type.AnnotatedTypeMetadata;
 import org.springframework.core.type.AnnotationMetadata;
-import org.springframework.util.ClassUtils;
 
 /**
  * General condition used with all session configuration classes.
  *
  * @author Tommy Ludwig
+ * @author Stephane Nicoll
  */
 class SessionCondition extends SpringBootCondition {
 
-	private static final boolean redisPresent = ClassUtils.isPresent(
-			"org.springframework.data.redis.core.RedisTemplate",
-			SessionCondition.class.getClassLoader());
-
 	@Override
 	public ConditionOutcome getMatchOutcome(ConditionContext context,
 			AnnotatedTypeMetadata metadata) {
@@ -46,10 +42,6 @@ class SessionCondition extends SpringBootCondition {
 		StoreType sessionStoreType = SessionStoreMappings
 				.getType(((AnnotationMetadata) metadata).getClassName());
 		if (!resolver.containsProperty("store-type")) {
-			if (sessionStoreType == StoreType.REDIS && redisPresent) {
-				return ConditionOutcome.match(
-						message.foundExactly("default store type of redis (deprecated)"));
-			}
 			return ConditionOutcome.noMatch(
 					message.didNotFind("spring.session.store-type property").atAll());
 		}

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

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -24,13 +24,10 @@ import org.junit.Test;
 import org.springframework.beans.DirectFieldAccessor;
 import org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration;
 import org.springframework.boot.redis.RedisTestServer;
-import org.springframework.boot.test.rule.OutputCapture;
 import org.springframework.session.data.redis.RedisFlushMode;
 import org.springframework.session.data.redis.RedisOperationsSessionRepository;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.hamcrest.CoreMatchers.not;
-import static org.hamcrest.Matchers.containsString;
 
 /**
  * Redis specific tests for {@link SessionAutoConfiguration}.
@@ -40,27 +37,14 @@ import static org.hamcrest.Matchers.containsString;
 public class SessionAutoConfigurationRedisTests
 		extends AbstractSessionAutoConfigurationTests {
 
-	@Rule
-	public OutputCapture output = new OutputCapture();
-
 	@Rule
 	public final RedisTestServer redis = new RedisTestServer();
 
-	@Test
-	public void redisSessionStoreIsTheDefault() {
-		load(Collections.<Class<?>>singletonList(RedisAutoConfiguration.class));
-		validateSpringSessionUsesRedis();
-		this.output.expect(containsString(
-				"Spring Session store type is mandatory: set 'spring.session.store-type=redis' in your configuration"));
-	}
-
 	@Test
 	public void redisSessionStore() {
 		load(Collections.<Class<?>>singletonList(RedisAutoConfiguration.class),
 				"spring.session.store-type=redis");
 		validateSpringSessionUsesRedis();
-		this.output.expect(not(containsString(
-				"Spring Session store type is mandatory: set 'spring.session.store-type=redis' in your configuration")));
 	}
 
 	private void validateSpringSessionUsesRedis() {

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -4998,7 +4998,7 @@ Spring Boot provides Spring Session auto-configuration for a wide range of store
 * Hazelcast
 * HashMap
 
-If Spring Session is available, you only need to choose the
+If Spring Session is available, you must choose the
 {sc-spring-boot-autoconfigure}/session/StoreType.{sc-ext}[`StoreType`] that you wish to
 use to store the sessions. For instance to use JDBC as backend store, you'd configure
 your application as follows:
@@ -5008,9 +5008,6 @@ your application as follows:
     spring.session.store-type=jdbc
 ----
 
-NOTE: For backward compatibility if Redis is available Spring Session will be automatically
-configured to use Redis.
-
 TIP: You can disable Spring Session by setting the `store-type` to `none`.
 
 Each store has specific additional settings. For instance it is possible to customize