allow customization of turbine clusterName via SPEL expression in applcation.properties.

Fixes gh-49

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

@@ -306,7 +306,7 @@ To run the Hystrix Dashboard annotate your Spring Boot main class with `@EnableH
 
 Looking at an individual instances Hystrix data is not very useful in terms of the overall health of the system.  https://github.com/Netflix/Turbine[Turbine] is an application that aggregates all of the relevant `/hystrix.stream` endpoints into a combined `/turbine.stream` for use in the Hystrix Dashboard.  Individual instances are located via Eureka.  Running Turbine is as simple as annotating your main class with the `@EnableTurbine` annotation.
 
-`turbine.appConfig` is a list of eureka serviceId's that turbine will use to lookup instances.  `turbine.aggregator.clusterConfig` is used to group instances together.  This comes from the eureka `InstanceInfo`.  It is currently hard coded to `InstanceInfo.getAppName()`.  The turbine stream is then used in the Hystrix dashboard using a url that looks like: http://my.turbine.sever:8080/turbine.stream?cluster=CUSTOMERS
+`turbine.appConfig` is a list of eureka serviceId's that turbine will use to lookup instances.  `turbine.aggregator.clusterConfig` is used to group instances together.  This comes from the eureka `InstanceInfo`.  The clusterName is a SPEL expression evaluated against the InstanceInfo.  The default clusterNameExpression is `appName`.  The turbine stream is then used in the Hystrix dashboard using a url that looks like: http://my.turbine.sever:8080/turbine.stream?cluster=CUSTOMERS
 
 The `cluster` parameter must match an entry in `turbine.aggregator.clusterConfig`.
 
@@ -317,6 +317,8 @@ turbine:
   appConfig: customers
 ----
 
+The clusterName can be customized by a SPEL expression in `turbine.clusterNameExpression`.  For example, `turbine.clusterNameExpression=aSGName` would get the clustername from the AWS ASG name.
+
 == Declarative REST Client: Feign
 
 https://github.com/Netflix/feign[Feign] is a declarative web service client.  It makes writing web service clients easier.  To use Feign create an interface and annotate it.  It has pluggable annotation support including Feign annotations and JAX-RS annotations. Feign also supports pluggable encoders and decoders.  Spring Cloud adds support for Spring MVC annotations and for using the same `HttpMessageConverters` used by default in Spring Web.  Spring Cloud integrates Ribbon and Eureka to provide a load balanced http client when using Feign.

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka/EurekaDiscoveryClient.java

@@ -3,7 +3,6 @@ package org.springframework.cloud.netflix.eureka;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.cloud.client.discovery.DiscoveryClient;
-import org.springframework.cloud.netflix.eureka.EurekaInstanceConfigBean;
 
 /**
  * @author Spencer Gibb

spring-cloud-netflix-turbine/pom.xml

@@ -38,5 +38,11 @@
 			<groupId>com.netflix.turbine</groupId>
 			<artifactId>turbine-core</artifactId>
 		</dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <!-- Only needed at compile time -->
+            <scope>provided</scope>
+        </dependency>
 	</dependencies>
 </project>

spring-cloud-netflix-turbine/src/main/java/org/springframework/cloud/netflix/turbine/EurekaInstanceDiscovery.java

@@ -12,6 +12,9 @@ import com.netflix.turbine.discovery.Instance;
 import com.netflix.turbine.discovery.InstanceDiscovery;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.expression.Expression;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
 
 import java.util.*;
 
@@ -29,10 +32,15 @@ public class EurekaInstanceDiscovery implements InstanceDiscovery {
     // Property the controls the list of applications that are enabled in Eureka
     private static final DynamicStringProperty ApplicationList = DynamicPropertyFactory.getInstance().getStringProperty("turbine.appConfig", "");
 
-    public EurekaInstanceDiscovery() {
+    private final Expression clusterNameExpression;
+
+    public EurekaInstanceDiscovery(TurbineProperties turbineProperties) {
         // Eureka client should already be configured by spring-platform-netflix-core
         // initialize eureka client.
         //DiscoveryManager.getInstance().initComponent(new MyDataCenterInstanceConfig(), new DefaultEurekaClientConfig());
+
+        SpelExpressionParser parser = new SpelExpressionParser();
+        clusterNameExpression = parser.parseExpression(turbineProperties.getClusterNameExpression());
     }
 
     /**
@@ -162,10 +170,12 @@ public class EurekaInstanceDiscovery implements InstanceDiscovery {
      * @return
      */
     protected String getClusterName(InstanceInfo iInfo) {
-        //TODO: make ASG configurable using app name for demo. //return iInfo.getASGName();
-        //AppGroupName is UPPERCASE from eureka
-        //return iInfo.getAppGroupName();
-        return iInfo.getAppName();
+        StandardEvaluationContext context = new StandardEvaluationContext(iInfo);
+        Object value = clusterNameExpression.getValue(context);
+        if (value != null) {
+            return value.toString();
+        }
+        return null;
     }
 
     /**

spring-cloud-netflix-turbine/src/main/java/org/springframework/cloud/netflix/turbine/TurbineConfiguration.java

@@ -5,6 +5,7 @@ import com.netflix.turbine.init.TurbineInit;
 import com.netflix.turbine.plugins.PluginsFactory;
 import com.netflix.turbine.streaming.servlet.TurbineStreamServlet;
 import org.springframework.boot.context.embedded.ServletRegistrationBean;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
 import org.springframework.context.SmartLifecycle;
 import org.springframework.context.annotation.Bean;
@@ -15,6 +16,7 @@ import org.springframework.core.Ordered;
  * @author Spencer Gibb
  */
 @Configuration
+@EnableConfigurationProperties
 @EnableEurekaClient
 public class TurbineConfiguration implements SmartLifecycle, Ordered {
 
@@ -23,9 +25,14 @@ public class TurbineConfiguration implements SmartLifecycle, Ordered {
         return new ServletRegistrationBean(new TurbineStreamServlet(), "/turbine.stream");
     }
 
+    @Bean
+    public TurbineProperties turbineProperties() {
+        return new TurbineProperties();
+    }
+
     @Bean
     public InstanceDiscovery instanceDiscovery() {
-        return new EurekaInstanceDiscovery();
+        return new EurekaInstanceDiscovery(turbineProperties());
     }
 
     private boolean running;

spring-cloud-netflix-turbine/src/main/java/org/springframework/cloud/netflix/turbine/TurbineProperties.java

@@ -0,0 +1,13 @@
+package org.springframework.cloud.netflix.turbine;
+
+import lombok.Data;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+/**
+ * @author Spencer Gibb
+ */
+@Data
+@ConfigurationProperties("turbine")
+public class TurbineProperties {
+    private String clusterNameExpression = "appName";
+}

spring-cloud-netflix-turbine/src/test/java/org/springframework/cloud/netflix/turbine/EurekaInstanceDiscoveryTest.java

@@ -0,0 +1,38 @@
+package org.springframework.cloud.netflix.turbine;
+
+import static org.junit.Assert.*;
+
+import com.netflix.appinfo.InstanceInfo;
+import org.junit.Test;
+
+/**
+ * @author Spencer Gibb
+ */
+public class EurekaInstanceDiscoveryTest {
+
+
+    @Test
+    public void testGetClusterName() {
+        String appName = "testAppName";
+        EurekaInstanceDiscovery discovery = new EurekaInstanceDiscovery(new TurbineProperties());
+        InstanceInfo instanceInfo = InstanceInfo.Builder.newBuilder()
+                .setAppName(appName)
+                .build();
+        String clusterName = discovery.getClusterName(instanceInfo);
+        assertEquals("clusterName is wrong", appName.toUpperCase(), clusterName);
+    }
+
+    @Test
+    public void testGetClusterNameCustomExpression() {
+        TurbineProperties turbineProperties = new TurbineProperties();
+        turbineProperties.setClusterNameExpression("aSGName");
+        EurekaInstanceDiscovery discovery = new EurekaInstanceDiscovery(turbineProperties);
+        String asgName = "myAsgName";
+        InstanceInfo instanceInfo = InstanceInfo.Builder.newBuilder()
+                .setAppName("testApp")
+                .setASGName(asgName)
+                .build();
+        String clusterName = discovery.getClusterName(instanceInfo);
+        assertEquals("clusterName is wrong", asgName, clusterName);
+    }
+}