Introduce build time flag property to disable the cache extension

extensions/cache/deployment/src/main/java/io/quarkus/cache/deployment/CacheConfig.java

@@ -14,6 +14,13 @@
 @ConfigRoot
 public class CacheConfig {
 
+    /**
+     * Whether or not the cache extension is enabled. If the extension is disabled, the caching annotations will have no effect
+     * at run time.
+     */
+    @ConfigItem(defaultValue = "true")
+    public boolean enabled;
+
     /**
      * Cache type.
      */

extensions/cache/deployment/src/main/java/io/quarkus/cache/deployment/CacheProcessor.java

@@ -11,6 +11,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.function.BooleanSupplier;
 
 import javax.enterprise.inject.spi.DeploymentException;
 
@@ -45,20 +46,20 @@ FeatureBuildItem feature() {
         return new FeatureBuildItem(Feature.CACHE);
     }
 
-    @BuildStep
+    @BuildStep(onlyIf = CacheEnabled.class)
     AnnotationsTransformerBuildItem annotationsTransformer() {
         return new AnnotationsTransformerBuildItem(new CacheAnnotationsTransformer());
     }
 
-    @BuildStep
+    @BuildStep(onlyIf = CacheEnabled.class)
     List<AdditionalBeanBuildItem> additionalBeans() {
         return Arrays.asList(
                 new AdditionalBeanBuildItem(CacheInvalidateAllInterceptor.class),
                 new AdditionalBeanBuildItem(CacheInvalidateInterceptor.class),
                 new AdditionalBeanBuildItem(CacheResultInterceptor.class));
     }
 
-    @BuildStep
+    @BuildStep(onlyIf = CacheEnabled.class)
     ValidationErrorBuildItem validateBeanDeployment(ValidationPhaseBuildItem validationPhase) {
         AnnotationStore annotationStore = validationPhase.getContext().get(Key.ANNOTATION_STORE);
         List<Throwable> throwables = new ArrayList<>();
@@ -74,7 +75,7 @@ ValidationErrorBuildItem validateBeanDeployment(ValidationPhaseBuildItem validat
         return new ValidationErrorBuildItem(throwables.toArray(new Throwable[0]));
     }
 
-    @BuildStep
+    @BuildStep(onlyIf = CacheEnabled.class)
     @Record(RUNTIME_INIT)
     void recordCachesBuild(CombinedIndexBuildItem combinedIndex, BeanContainerBuildItem beanContainer, CacheConfig config,
             CaffeineCacheBuildRecorder caffeineRecorder,
@@ -113,4 +114,13 @@ private Set<String> getCacheNames(IndexView index) {
         }
         return cacheNames;
     }
+
+    private static class CacheEnabled implements BooleanSupplier {
+
+        CacheConfig config;
+
+        public boolean getAsBoolean() {
+            return config.enabled;
+        }
+    }
 }

extensions/cache/deployment/src/test/java/io/quarkus/cache/test/deployment/DisabledCacheTest.java

@@ -0,0 +1,43 @@
+package io.quarkus.cache.test.deployment;
+
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+import javax.enterprise.context.Dependent;
+import javax.inject.Inject;
+
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.asset.StringAsset;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.cache.CacheResult;
+import io.quarkus.test.QuarkusUnitTest;
+
+public class DisabledCacheTest {
+
+    @RegisterExtension
+    static final QuarkusUnitTest TEST = new QuarkusUnitTest()
+            .setArchiveProducer(() -> ShrinkWrap.create(JavaArchive.class)
+                    .addAsResource(new StringAsset("quarkus.cache.enabled=false"), "application.properties")
+                    .addClass(CachedService.class));
+
+    private static final String KEY = "key";
+
+    @Inject
+    CachedService cachedService;
+
+    @Test
+    public void testEnabledFlagProperty() {
+        assertNotEquals(cachedService.cachedMethod(KEY), cachedService.cachedMethod(KEY));
+    }
+
+    @Dependent
+    static class CachedService {
+
+        @CacheResult(cacheName = "test-cache")
+        public Object cachedMethod(String key) {
+            return new Object();
+        }
+    }
+}