From d96115c1b8ddfdd36e16a62ce9d7e33949806184 Mon Sep 17 00:00:00 2001
From: Spencer Gibb <spencer@gibb.us>
Date: Fri, 16 Jan 2015 13:28:38 -0700
Subject: [PATCH] uses a ImportSelector that imports the
 NoopDiscoveryClientConfiguration if @EnableDiscoveryClient is not used.

fixes gh-6
---
 .../SingleImplementationImportSelector.java   |  5 ++
 .../NoopDiscoveryClientConfiguration.java     |  5 +-
 .../NoopDiscoveryClientImportSelector.java    | 46 +++++++++++++++++++
 src/main/resources/META-INF/spring.factories  |  2 +-
 4 files changed, 53 insertions(+), 5 deletions(-)
 create mode 100644 src/main/java/org/springframework/cloud/client/discovery/NoopDiscoveryClientImportSelector.java

diff --git a/src/main/java/org/springframework/cloud/client/SingleImplementationImportSelector.java b/src/main/java/org/springframework/cloud/client/SingleImplementationImportSelector.java
index e6410712..132ea6d3 100644
--- a/src/main/java/org/springframework/cloud/client/SingleImplementationImportSelector.java
+++ b/src/main/java/org/springframework/cloud/client/SingleImplementationImportSelector.java
@@ -71,6 +71,11 @@ public abstract class SingleImplementationImportSelector<T> implements
 				SpringFactoriesLoader.loadFactoryNames(this.annotationClass,
 						this.beanClassLoader)));
 
+		if (factories.isEmpty()) {
+			throw new IllegalStateException("Annotation @" + getSimpleName() +
+					" found, but there are no implementations.  Did you forget to include a starter?");
+		}
+
 		if (factories.size() > 1) {
 			String factory = factories.get(0);
 			// there should only every be one DiscoveryClient
diff --git a/src/main/java/org/springframework/cloud/client/discovery/NoopDiscoveryClientConfiguration.java b/src/main/java/org/springframework/cloud/client/discovery/NoopDiscoveryClientConfiguration.java
index cd7c27ea..09ff6e07 100644
--- a/src/main/java/org/springframework/cloud/client/discovery/NoopDiscoveryClientConfiguration.java
+++ b/src/main/java/org/springframework/cloud/client/discovery/NoopDiscoveryClientConfiguration.java
@@ -22,9 +22,8 @@ import java.net.UnknownHostException;
 import javax.annotation.PostConstruct;
 
 import lombok.extern.apachecommons.CommonsLog;
+
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.context.embedded.EmbeddedServletContainer;
 import org.springframework.boot.context.embedded.EmbeddedWebApplicationContext;
@@ -42,8 +41,6 @@ import org.springframework.core.env.Environment;
  */
 @Configuration
 @EnableConfigurationProperties
-@ConditionalOnMissingClass(name = "com.netflix.discovery.EurekaClientConfig")
-@ConditionalOnProperty(value = "eureka.client.enabled", havingValue = "false")
 @CommonsLog
 public class NoopDiscoveryClientConfiguration implements
 		ApplicationListener<ContextRefreshedEvent> {
diff --git a/src/main/java/org/springframework/cloud/client/discovery/NoopDiscoveryClientImportSelector.java b/src/main/java/org/springframework/cloud/client/discovery/NoopDiscoveryClientImportSelector.java
new file mode 100644
index 00000000..8a5190df
--- /dev/null
+++ b/src/main/java/org/springframework/cloud/client/discovery/NoopDiscoveryClientImportSelector.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2013-2015 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 org.springframework.cloud.client.discovery;
+
+import lombok.extern.apachecommons.CommonsLog;
+
+import org.springframework.context.annotation.DeferredImportSelector;
+import org.springframework.core.annotation.AnnotationAttributes;
+import org.springframework.core.type.AnnotationMetadata;
+
+/**
+ * Import Selector that only returns a NoopDiscoveryClientConfiguration if the
+ * @EnableDiscoveryClient annotation has NOT been used.
+ * @author Spencer Gibb
+ */
+@CommonsLog
+public class NoopDiscoveryClientImportSelector implements
+		DeferredImportSelector {
+
+	@Override
+	public String[] selectImports(AnnotationMetadata metadata) {
+		AnnotationAttributes attributes = AnnotationAttributes.fromMap(metadata
+				.getAnnotationAttributes(EnableDiscoveryClient.class.getName(), true));
+
+		if (attributes == null) {
+			// @EnableDiscoveryClient has not been used, so configure the noop client
+			return new String[] { NoopDiscoveryClientConfiguration.class.getName() };
+		}
+
+		return new String[]{};
+	}
+}
diff --git a/src/main/resources/META-INF/spring.factories b/src/main/resources/META-INF/spring.factories
index 9ea05d30..d5290402 100644
--- a/src/main/resources/META-INF/spring.factories
+++ b/src/main/resources/META-INF/spring.factories
@@ -1,4 +1,4 @@
 # Bootstrap Configuration
 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
 org.springframework.cloud.client.CommonsClientAutoConfiguration,\
-org.springframework.cloud.client.discovery.NoopDiscoveryClientConfiguration
+org.springframework.cloud.client.discovery.NoopDiscoveryClientImportSelector