Add support for placeholders in @FeignClient definitions

docs/src/main/asciidoc/spring-cloud-netflix.adoc

@@ -790,6 +790,16 @@ NOTE: The `serviceId` attribute is now deprecated in favor of the `name` attribu
 
 WARNING: Previously, using the `url` attribute, did not require the `name` attribute. Using `name` is now required.
 
+Placeholders are supported in the `name` and `url` attributes.
+
+[source,java,indent=0]
+----
+@FeignClient(name = "${feign.name}", url = "${feign.url}")
+public interface StoreClient {
+    //..
+}
+----
+
 Spring Cloud Netflix provides the following beans by default for feign (`BeanType` beanName: `ClassName`):
 
 * `Decoder` feignDecoder: `ResponseEntityDecoder` (which wraps a `SpringDecoder`)

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignClient.java

@@ -39,14 +39,16 @@ public @interface FeignClient {
 
 	/**
 	 * The serviceId with optional protocol prefix. Synonym for {@link #serviceId()
-	 * serviceId}. Either serviceId or url must be specified but not both.
+	 * serviceId}. Either serviceId or url must be specified but not both. Can be
+     * specified as property key, eg: ${propertyKey}.
 	 */
 	@AliasFor("name")
 	String value() default "";
 
 	/**
 	 * The serviceId with optional protocol prefix. Synonym for {@link #value() value}.
-	 * Either serviceId or url must be specified but not both.
+	 * Either serviceId or url must be specified but not both. Can be
+     * specified as property key, eg: ${propertyKey}.
 	 *
 	 * @deprecated use {@link #name() name} instead
 	 */

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignClientsRegistrar.java

@@ -18,8 +18,10 @@ package org.springframework.cloud.netflix.feign;
 
 import java.io.IOException;
 import java.lang.annotation.Annotation;
+import java.net.MalformedURLException;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.net.URL;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
@@ -34,6 +36,7 @@ import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.ResourceLoaderAware;
 import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
 import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
@@ -186,9 +189,11 @@ public class FeignClientsRegistrar implements ImportBeanDefinitionRegistrar,
 		if (!StringUtils.hasText(name)) {
 			name = (String) attributes.get("value");
 		}
+		name = resolve(name);
 		if (!StringUtils.hasText(name)) {
 			return "";
 		}
+
 		String host = null;
 		try {
 			host = new URI("http://" + name).getHost();
@@ -199,8 +204,25 @@ public class FeignClientsRegistrar implements ImportBeanDefinitionRegistrar,
 		return name;
 	}
 
+	private String resolve(String value) {
+		if (StringUtils.hasText(value )
+				&& this.resourceLoader instanceof ConfigurableApplicationContext) {
+			return ((ConfigurableApplicationContext)this.resourceLoader)
+					.getEnvironment().resolvePlaceholders(value);
+		}
+		return value;
+	}
+
 	private String getUrl(Map<String, Object> attributes) {
-		return (String) attributes.get("url");
+		String url = resolve((String) attributes.get("url"));
+		if (StringUtils.hasText(url)) {
+			try {
+				new URL(url);
+			} catch (MalformedURLException e) {
+				throw new IllegalArgumentException(url + " is malformed", e);
+			}
+		}
+		return url;
 	}
 
 	protected ClassPathScanningCandidateComponentProvider getScanner() {

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/valid/FeignClientValidationTests.java

@@ -58,6 +58,28 @@ public class FeignClientValidationTests {
 	}
 
 	@Test
+	public void validPlaceholder() {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
+				PlaceholderUrlConfiguration.class);
+		assertNotNull(context.getBean(PlaceholderUrlConfiguration.Client.class));
+		context.close();
+	}
+
+	@Configuration
+	@Import(FeignAutoConfiguration.class)
+	@EnableFeignClients(clients = PlaceholderUrlConfiguration.Client.class)
+	protected static class PlaceholderUrlConfiguration {
+
+		@FeignClient(name="example", url="${feignClient.url:http://example.com}")
+		interface Client {
+			@RequestMapping(method = RequestMethod.GET, value = "/")
+			@Deprecated
+			String get();
+		}
+
+	}
+
+	@Test
 	public void validLoadBalanced() {
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
 				RibbonAutoConfiguration.class,

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/valid/scanning/FeignClientScanningTests.java

@@ -61,6 +61,9 @@ public class FeignClientScanningTests {
 	private TestClient testClient;
 
 	@Autowired
+	private TestClientByKey testClientByKey;
+    
+	@Autowired
 	private Client feignClient;
 
 	@FeignClient("localapp")
@@ -69,6 +72,12 @@ public class FeignClientScanningTests {
 		String getHello();
 	}
 
+	@FeignClient("${feignClient.localappName}")
+	protected interface TestClientByKey {
+		@RequestMapping(method = RequestMethod.GET, value = "/hello")
+		String getHello();
+	}
+    
 	@Configuration
 	@EnableAutoConfiguration
 	@RestController
@@ -94,6 +103,13 @@ public class FeignClientScanningTests {
 		assertEquals("first hello didn't match", "hello world 1", hello);
 	}
 
+	@Test
+	public void testSimpleTypeByKey() {
+		String hello = this.testClientByKey.getHello();
+		assertNotNull("hello was null", hello);
+		assertEquals("first hello didn't match", "hello world 1", hello);
+	}
+    
 	// Load balancer with fixed server list for "local" pointing to localhost
 	@Configuration
 	public static class LocalRibbonClientConfiguration {

spring-cloud-netflix-core/src/test/resources/application.yml

@@ -37,3 +37,5 @@ zuul:
     stores:
       url: http://localhost:8081
       path: /stores/**
+feignClient:
+  localappName: localapp
\ No newline at end of file