only create Discovery*HealthIndicator beans if DiscoveryClient is a bean and spring.cloud.discovery.enable = true.

Allow discovery and circuit breaker to be turned off by properties.

fixes gh-2

src/main/java/org/springframework/cloud/client/CommonsClientAutoConfiguration.java

@@ -2,7 +2,10 @@ package org.springframework.cloud.client;
 
 import org.springframework.boot.actuate.health.HealthAggregator;
 import org.springframework.boot.actuate.health.HealthIndicator;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnExpression;
+import org.springframework.cloud.client.discovery.DiscoveryClient;
 import org.springframework.cloud.client.discovery.DiscoveryClientHealthIndicator;
 import org.springframework.cloud.client.discovery.DiscoveryCompositeHealthIndicator;
 import org.springframework.cloud.client.discovery.DiscoveryHealthIndicator;
@@ -20,13 +23,18 @@ import java.util.List;
 @Order(0)
 public class CommonsClientAutoConfiguration {
 
-	@Bean
-	public DiscoveryClientHealthIndicator instancesHealthIndicator() {
-		return new DiscoveryClientHealthIndicator();
-	}
+	@Configuration
+	@ConditionalOnBean(DiscoveryClient.class)
+	@ConditionalOnExpression("${spring.cloud.discovery.enabled:true}")
+	protected static class HealthConfiguration {
+		@Bean
+		public DiscoveryClientHealthIndicator instancesHealthIndicator(DiscoveryClient discoveryClient) {
+			return new DiscoveryClientHealthIndicator(discoveryClient);
+		}
 
-    @Bean
-    public DiscoveryCompositeHealthIndicator discoveryHealthIndicator(HealthAggregator aggregator, List<DiscoveryHealthIndicator> indicators) {
-        return new DiscoveryCompositeHealthIndicator(aggregator, indicators);
-    }
+		@Bean
+		public DiscoveryCompositeHealthIndicator discoveryHealthIndicator(HealthAggregator aggregator, List<DiscoveryHealthIndicator> indicators) {
+			return new DiscoveryCompositeHealthIndicator(aggregator, indicators);
+		}
+	}
 }

src/main/java/org/springframework/cloud/client/SingleImplementationImportSelector.java

@@ -2,9 +2,11 @@ package org.springframework.cloud.client;
 
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.BeanClassLoaderAware;
+import org.springframework.context.EnvironmentAware;
 import org.springframework.context.annotation.DeferredImportSelector;
 import org.springframework.core.GenericTypeResolver;
 import org.springframework.core.annotation.AnnotationAttributes;
+import org.springframework.core.env.Environment;
 import org.springframework.core.io.support.SpringFactoriesLoader;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.util.Assert;
@@ -19,11 +21,12 @@ import java.util.List;
  * @author Spencer Gibb
  */
 @Slf4j
-public abstract class SingleImplementationImportSelector<T> implements DeferredImportSelector, BeanClassLoaderAware {
+public abstract class SingleImplementationImportSelector<T> implements DeferredImportSelector, BeanClassLoaderAware, EnvironmentAware {
 
     protected ClassLoader beanClassLoader;
 
     protected Class<T> annotationClass;
+    protected Environment environment;
 
     @SuppressWarnings("unchecked")
     protected SingleImplementationImportSelector() {
@@ -32,6 +35,9 @@ public abstract class SingleImplementationImportSelector<T> implements DeferredI
 
     @Override
     public String[] selectImports(AnnotationMetadata metadata) {
+        if (!isEnabled()) {
+            return new String[0];
+        }
         AnnotationAttributes attributes = AnnotationAttributes.fromMap(metadata
                 .getAnnotationAttributes(annotationClass.getName(),
                         true));
@@ -55,10 +61,17 @@ public abstract class SingleImplementationImportSelector<T> implements DeferredI
 
     }
 
+    protected abstract boolean isEnabled();
+
     protected String getSimpleName() {
         return annotationClass.getSimpleName();
     }
 
+    @Override
+    public void setEnvironment(Environment environment) {
+        this.environment = environment;
+    }
+
     @Override
     public void setBeanClassLoader(ClassLoader classLoader) {
         this.beanClassLoader = classLoader;

src/main/java/org/springframework/cloud/client/circuitbreaker/EnableCircuitBreakerImportSelector.java

@@ -1,5 +1,6 @@
 package org.springframework.cloud.client.circuitbreaker;
 
+import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.cloud.client.SingleImplementationImportSelector;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
@@ -10,4 +11,8 @@ import org.springframework.core.annotation.Order;
 @Order(Ordered.LOWEST_PRECEDENCE - 100)
 public class EnableCircuitBreakerImportSelector extends SingleImplementationImportSelector<EnableCircuitBreaker> {
 
+	@Override
+	protected boolean isEnabled() {
+		return new RelaxedPropertyResolver(environment).getProperty("spring.cloud.circuit.breaker.enabled", Boolean.class, Boolean.TRUE);
+	}
 }

src/main/java/org/springframework/cloud/client/discovery/DiscoveryClientHealthIndicator.java

@@ -20,18 +20,18 @@ public class DiscoveryClientHealthIndicator implements ApplicationContextAware,
     private ApplicationContext context;
 
 	private int order = Ordered.HIGHEST_PRECEDENCE;
+	private DiscoveryClient discoveryClient;
+
+	public DiscoveryClientHealthIndicator(DiscoveryClient discoveryClient) {
+		this.discoveryClient = discoveryClient;
+	}
 
 	@Override
 	public Health health() {
 		Health.Builder builder = new Health.Builder();
         try {
-			DiscoveryClient client = context.getBean(DiscoveryClient.class);
-            if (client == null) {
-                builder.unknown().withDetail("warning", "No DiscoveryClient found");
-                return builder.build();
-            }
-			List<String> services = client.getServices();
-            builder.status(new Status("UP", client.description()))
+			List<String> services = discoveryClient.getServices();
+            builder.status(new Status("UP", discoveryClient.description()))
 					.withDetail("services", services);
         } catch (Exception e) {
             log.error("Error", e);

src/main/java/org/springframework/cloud/client/discovery/EnableDiscoveryClientImportSelector.java

@@ -1,5 +1,6 @@
 package org.springframework.cloud.client.discovery;
 
+import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.cloud.client.SingleImplementationImportSelector;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
@@ -10,4 +11,8 @@ import org.springframework.core.annotation.Order;
 @Order(Ordered.LOWEST_PRECEDENCE - 100)
 public class EnableDiscoveryClientImportSelector extends SingleImplementationImportSelector<EnableDiscoveryClient> {
 
+	@Override
+	protected boolean isEnabled() {
+		return new RelaxedPropertyResolver(environment).getProperty("spring.cloud.discovery.enabled", Boolean.class, Boolean.TRUE);
+	}
 }

src/test/java/org/springframework/cloud/client/SingleImplementationImportSelectorTests.java

@@ -16,5 +16,10 @@ public class SingleImplementationImportSelectorTests {
     }
 
     public static @interface MyAnnotation {}
-    public static class MyAnnotationImportSelector extends SingleImplementationImportSelector<MyAnnotation> {  }
+    public static class MyAnnotationImportSelector extends SingleImplementationImportSelector<MyAnnotation> {
+        @Override
+        protected boolean isEnabled() {
+            return true;
+        }
+    }
 }