Allow custom CacheResolver

Previously, if a bean of type `CacheResolver` was present in the context
the whole cache auto-configuration would back off. If said
`CacheResolver` hasn't been defined via the `CachingConfigurer`
infrastructure, the application context would fail with a rather
unpleasant error message.

It can be quite common to define custom `CacheResolver` beans as the cache
annotations allow to defines custom cache resolvers per operation. This
commit makes sure that the cache auto-configuration will back-off only if
the `CacheResolver` is named `cacheResolver`.

Closes spring-projectsgh-5201

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/cache/CacheAutoConfiguration.java

@@ -38,7 +38,6 @@
 import org.springframework.cache.CacheManager;
 import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.cache.interceptor.CacheAspectSupport;
-import org.springframework.cache.interceptor.CacheResolver;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
@@ -62,7 +61,7 @@
 @Configuration
 @ConditionalOnClass(CacheManager.class)
 @ConditionalOnBean(CacheAspectSupport.class)
-@ConditionalOnMissingBean({ CacheManager.class, CacheResolver.class })
+@ConditionalOnMissingBean(value = CacheManager.class, name = "cacheResolver")
 @EnableConfigurationProperties(CacheProperties.class)
 @AutoConfigureBefore(HibernateJpaAutoConfiguration.class)
 @AutoConfigureAfter({ HazelcastAutoConfiguration.class, RedisAutoConfiguration.class })

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/cache/CacheAutoConfigurationTests.java

@@ -127,12 +127,19 @@ public void cacheManagerFromSupportBackOff() {
 	}
 
 	@Test
-	public void cacheResolverBackOff() throws Exception {
-		load(CustomCacheResolverConfiguration.class);
+	public void cacheResolverFromSupportBackOff() throws Exception {
+		load(CustomCacheResolverFromSupportConfiguration.class);
 		this.thrown.expect(NoSuchBeanDefinitionException.class);
 		this.context.getBean(CacheManager.class);
 	}
 
+	@Test
+	public void customCacheResolverCanBeDefined() throws Exception {
+		load(SpecificCacheResolverConfiguration.class, "spring.cache.type=simple");
+		validateCacheManager(ConcurrentMapCacheManager.class);
+		assertThat(this.context.getBeansOfType(CacheResolver.class)).hasSize(1);
+	}
+
 	@Test
 	public void notSupportedCachingMode() {
 		this.thrown.expect(BeanCreationException.class);
@@ -833,7 +840,7 @@ public ConfigurationBuilder configurationBuilder() {
 	}
 
 	@Configuration
-	@Import({ GenericCacheConfiguration.class, RedisCacheConfiguration.class })
+	@EnableCaching
 	static class CustomCacheManagerConfiguration {
 
 		@Bean
@@ -844,7 +851,7 @@ public CacheManager cacheManager() {
 	}
 
 	@Configuration
-	@Import({ GenericCacheConfiguration.class, RedisCacheConfiguration.class })
+	@EnableCaching
 	static class CustomCacheManagerFromSupportConfiguration
 			extends CachingConfigurerSupport {
 
@@ -859,18 +866,7 @@ public CacheManager cacheManager() {
 
 	@Configuration
 	@EnableCaching
-	static class GuavaCacheBuilderConfiguration {
-
-		@Bean
-		CacheBuilder<Object, Object> cacheBuilder() {
-			return CacheBuilder.newBuilder().recordStats();
-		}
-
-	}
-
-	@Configuration
-	@Import({ GenericCacheConfiguration.class, RedisCacheConfiguration.class })
-	static class CustomCacheResolverConfiguration extends CachingConfigurerSupport {
+	static class CustomCacheResolverFromSupportConfiguration extends CachingConfigurerSupport {
 
 		@Override
 		@Bean
@@ -890,6 +886,28 @@ public Collection<? extends Cache> resolveCaches(
 
 	}
 
+	@Configuration
+	@EnableCaching
+	static class SpecificCacheResolverConfiguration {
+
+		@Bean
+		public CacheResolver myCacheResolver() {
+			return mock(CacheResolver.class);
+		}
+
+	}
+
+	@Configuration
+	@EnableCaching
+	static class GuavaCacheBuilderConfiguration {
+
+		@Bean
+		CacheBuilder<Object, Object> cacheBuilder() {
+			return CacheBuilder.newBuilder().recordStats();
+		}
+
+	}
+
 	@Configuration
 	@EnableCaching
 	static class CaffeineCacheBuilderConfiguration {

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

@@ -3241,7 +3241,9 @@ TIP: Use the `spring-boot-starter-cache` "`Starter POM`" to quickly add required
 dependencies. If you are adding dependencies manually you should note that certain
 implementations are only provided by the `spring-context-support` jar.
 
-Spring Boot tries to detect the following providers (in this order):
+If you haven't defined a bean of type `CacheManager` or a `CacheResolver` named
+`cacheResolver` (see `CachingConfigurer`), Spring Boot tries to detect the following
+providers (in this order):
 
 * <<boot-features-caching-provider-generic,Generic>>
 * <<boot-features-caching-provider-jcache,JCache (JSR-107)>>