Calculate the default instance id.

spring-cloud-commons/src/main/java/org/springframework/cloud/util/IdUtils.java

@@ -0,0 +1,44 @@
+package org.springframework.cloud.util;
+
+import org.springframework.boot.bind.RelaxedPropertyResolver;
+import org.springframework.core.env.PropertyResolver;
+import org.springframework.util.StringUtils;
+
+/**
+ * @author Spencer Gibb
+ */
+public class IdUtils {
+
+	private static final String SEPARATOR = ":";
+
+	public static String getDefaultInstanceId(PropertyResolver resolver) {
+		RelaxedPropertyResolver relaxed = new RelaxedPropertyResolver(resolver);
+		String vcapInstanceId = relaxed.getProperty("vcap.application.instance_id");
+		if (StringUtils.hasText(vcapInstanceId)) {
+			return vcapInstanceId;
+		}
+
+		String hostname = relaxed.getProperty("spring.cloud.client.hostname");
+		String appName = relaxed.getProperty("spring.application.name");
+
+		String namePart = combineParts(hostname, SEPARATOR, appName);
+
+		String indexPart = relaxed.getProperty("spring.application.instance_id",
+				relaxed.getProperty("server.port"));
+
+		return combineParts(namePart, SEPARATOR, indexPart);
+	}
+
+	public static String combineParts(String firstPart, String separator, String secondPart) {
+		String combined = null;
+		if (firstPart != null && secondPart != null) {
+			combined = firstPart + separator + secondPart;
+		} else if (firstPart != null) {
+			combined = firstPart;
+		} else if (secondPart != null) {
+			combined = secondPart;
+		}
+		return combined;
+	}
+
+}

spring-cloud-commons/src/test/java/org/springframework/cloud/util/IdUtilsTests.java

@@ -0,0 +1,94 @@
+package org.springframework.cloud.util;
+
+import static org.junit.Assert.*;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.mock.env.MockEnvironment;
+
+/**
+ * @author Spencer Gibb
+ */
+public class IdUtilsTests {
+
+	public static final String DEFAULT_ID = "id1";
+	private MockEnvironment env;
+
+	@Before
+	public void setup() {
+		env = new MockEnvironment();
+	}
+
+	@After
+	public void destroy() {
+		env = null;
+	}
+
+	@Test
+	public void emptyEnvironmentWorks() {
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertNull("instanceId was not null", instanceId);
+	}
+
+	@Test
+	public void vcapInstanceIdWorks() {
+		env.setProperty("vcap.application.instance_id", DEFAULT_ID);
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertEquals("instanceId was wrong", DEFAULT_ID, instanceId);
+	}
+
+	@Test
+	public void hostnameWorks() {
+		env.setProperty("spring.cloud.client.hostname", DEFAULT_ID);
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertEquals("instanceId was wrong", DEFAULT_ID, instanceId);
+	}
+
+	@Test
+	public void appNameWorks() {
+		env.setProperty("spring.application.name", DEFAULT_ID);
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertEquals("instanceId was wrong", DEFAULT_ID, instanceId);
+	}
+
+	@Test
+	public void hostnameAndAppNameWorks() {
+		env.setProperty("spring.application.name", DEFAULT_ID);
+		env.setProperty("spring.cloud.client.hostname", DEFAULT_ID+"2");
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertEquals("instanceId was wrong", DEFAULT_ID+"2"+":"+DEFAULT_ID, instanceId);
+	}
+
+	@Test
+	public void instanceIdWorks() {
+		env.setProperty("spring.cloud.client.hostname", DEFAULT_ID);
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertEquals("instanceId was wrong", DEFAULT_ID, instanceId);
+	}
+
+	@Test
+	public void portWorks() {
+		env.setProperty("spring.application.name", DEFAULT_ID);
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertEquals("instanceId was wrong", DEFAULT_ID, instanceId);
+	}
+
+	@Test
+	public void appNameAndPortWorks() {
+		env.setProperty("spring.application.name", DEFAULT_ID);
+		env.setProperty("server.port", "80");
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertEquals("instanceId was wrong", DEFAULT_ID+":80", instanceId);
+	}
+
+	@Test
+	public void fullWorks() {
+		env.setProperty("spring.cloud.client.hostname", "myhost");
+		env.setProperty("spring.application.name", DEFAULT_ID);
+		env.setProperty("server.port", "80");
+		String instanceId = IdUtils.getDefaultInstanceId(env);
+		assertEquals("instanceId was wrong", "myhost:"+DEFAULT_ID+":80", instanceId);
+	}
+
+}