Return address from the interface with lowest index

Also fixes unclosed closeable warnings

Fixes gh-82

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

@@ -77,12 +77,20 @@ public class InetUtils implements Closeable {
 	}
 
 	public InetAddress findFirstNonLoopbackAddress() {
+		InetAddress result = null;
 		try {
+			int lowest = Integer.MAX_VALUE;
 			for (Enumeration<NetworkInterface> nics = NetworkInterface
 					.getNetworkInterfaces(); nics.hasMoreElements();) {
 				NetworkInterface ifc = nics.nextElement();
 				if (ifc.isUp()) {
 					log.trace("Testing interface: " + ifc.getDisplayName());
+					if (ifc.getIndex() < lowest || result == null) {
+						lowest = ifc.getIndex();
+					}
+					else if (result != null) {
+						continue;
+					}
 
 					// @formatter:off
 					if (!ignoreInterface(ifc.getDisplayName())) {
@@ -93,7 +101,7 @@ public class InetUtils implements Closeable {
 									&& !address.isLoopbackAddress()) {
 								log.trace("Found non-loopback interface: "
 										+ ifc.getDisplayName());
-								return address;
+								result = address;
 							}
 						}
 					}
@@ -105,6 +113,10 @@ public class InetUtils implements Closeable {
 			log.error("Cannot get first non-loopback address", ex);
 		}
 
+		if (result != null) {
+			return result;
+		}
+
 		try {
 			return InetAddress.getLocalHost();
 		}

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

@@ -34,28 +34,32 @@ public class InetUtilsTests {
 
 	@Test
 	public void testGetFirstNonLoopbackHostInfo() {
-		assertNotNull(
-				new InetUtils(new InetUtilsProperties()).findFirstNonLoopbackHostInfo());
+		try (InetUtils utils = new InetUtils(new InetUtilsProperties())) {
+			assertNotNull(utils.findFirstNonLoopbackHostInfo());
+		}
 	}
 
 	@Test
 	public void testGetFirstNonLoopbackAddress() {
-		assertNotNull(
-				new InetUtils(new InetUtilsProperties()).findFirstNonLoopbackAddress());
+		try (InetUtils utils = new InetUtils(new InetUtilsProperties())) {
+			assertNotNull(utils.findFirstNonLoopbackAddress());
+		}
 	}
 
 	@Test
 	public void testConvert() throws Exception {
-		assertNotNull(new InetUtils(new InetUtilsProperties())
-				.convertAddress(InetAddress.getByName("localhost")));
+		try (InetUtils utils = new InetUtils(new InetUtilsProperties())) {
+			assertNotNull(utils.convertAddress(InetAddress.getByName("localhost")));
+		}
 		assertNotNull(InetUtils.convert(InetAddress.getByName("localhost")));
 	}
 
 	@Test
 	public void testHostInfo() throws Exception {
-		HostInfo info = new InetUtils(new InetUtilsProperties())
-				.findFirstNonLoopbackHostInfo();
-		assertNotNull(info.getIpAddressAsInt());
+		try (InetUtils utils = new InetUtils(new InetUtilsProperties())) {
+			HostInfo info = utils.findFirstNonLoopbackHostInfo();
+			assertNotNull(info.getIpAddressAsInt());
+		}
 	}
 
 	@Test
@@ -66,14 +70,20 @@ public class InetUtilsTests {
 		// interface.
 		// https://docs.docker.com/v1.7/articles/networking/
 		properties.setIgnoredInterfaces(Arrays.asList("docker0", "veth.*"));
-		InetUtils inetUtils = new InetUtils(properties);
+		try (InetUtils inetUtils = new InetUtils(properties)) {
 
-		assertTrue("docker0 not ignored", inetUtils.ignoreInterface("docker0"));
-		assertTrue("vethAQI2QT0 not ignored", inetUtils.ignoreInterface("vethAQI2QT"));
-		assertFalse("docker1 ignored", inetUtils.ignoreInterface("docker1"));
+			assertTrue("docker0 not ignored", inetUtils.ignoreInterface("docker0"));
+			assertTrue("vethAQI2QT0 not ignored",
+					inetUtils.ignoreInterface("vethAQI2QT"));
+			assertFalse("docker1 ignored", inetUtils.ignoreInterface("docker1"));
+		}
+	}
 
-		assertFalse("docker0 ignored",
-				new InetUtils(new InetUtilsProperties()).ignoreInterface("docker0"));
+	@Test
+	public void testDefaultIgnoreInterface() {
+		try (InetUtils inetUtils = new InetUtils(new InetUtilsProperties())) {
+			assertFalse("docker0 ignored", inetUtils.ignoreInterface("docker0"));
+		}
 	}
 
 }