Add new properties to inetutils: useOnlySiteLocalInterfaces and preferredNetworks

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

@@ -393,7 +393,7 @@ TIP: If you see errors like `java.lang.IllegalArgumentException: Can not set org
 [[ignore-network-interfaces]]
 === Ignore Network Interfaces
 
-Sometimes it is useful to ignore certain named network interfaces so they can be excluded from Service Discovery registration (eg. running in a Docker container). A list of regular expressions can be set that will cause the desired network interfaces to be ignored. The following configuration will ignore the "docker0" interface and all interfaces that start with "veth".
+Sometimes it is useful to ignore certain named network interfaces so they can be excluded from Service Discovery registration (eg. running in a Docker container). A list of regular expressions can be set that will cause the desired network interfaces to be ignored. The following configuration will ignore the "docker0" interface and all interfaces that start with "veth". 
 
 .application.yml
 ----
@@ -403,4 +403,26 @@ spring:
       ignoredInterfaces:
         - docker0
         - veth.*
-----
+----
+
+You can also force to use only specified network addresses using list of regular expressions:
+
+.application.yml
+----
+spring:
+  cloud:
+    inetutils:
+      preferredNetworks:
+        - 192.168
+        - 10.0
+----
+
+You can also force to use only site local addresses. See https://docs.oracle.com/javase/8/docs/api/java/net/Inet4Address.html#isSiteLocalAddress--[Inet4Address.html.isSiteLocalAddress()] for more details what is site local address.
+
+.application.yml
+----
+spring:
+  cloud:
+    inetutils:
+      useOnlySiteLocalInterfaces: true
+----

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

@@ -98,7 +98,8 @@ else if (result != null) {
 								.getInetAddresses(); addrs.hasMoreElements();) {
 							InetAddress address = addrs.nextElement();
 							if (address instanceof Inet4Address
-									&& !address.isLoopbackAddress()) {
+									&& !address.isLoopbackAddress()
+									&& !ignoreAddress(address)) {
 								log.trace("Found non-loopback interface: "
 										+ ifc.getDisplayName());
 								result = address;
@@ -127,6 +128,22 @@ else if (result != null) {
 		return null;
 	}
 
+	boolean ignoreAddress(InetAddress address) {
+
+		if (this.properties.isUseOnlySiteLocalInterfaces() && !address.isSiteLocalAddress()) {
+			log.trace("Ignoring address: " + address.getHostAddress());
+			return true;
+		}
+
+		for (String regex : this.properties.getPreferredNetworks()) {
+		if (address.getHostAddress().matches(regex) || address.getHostAddress().startsWith(regex)) {
+			log.trace("Ignoring address: " + address.getHostAddress());
+				return true;
+			}
+		}
+		return false;
+	}
+
 	boolean ignoreInterface(String interfaceName) {
 		for (String regex : this.properties.getIgnoredInterfaces()) {
 			if (interfaceName.matches(regex)) {

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

@@ -1,5 +1,6 @@
 package org.springframework.cloud.commons.util;
 
+import java.net.InetAddress;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -36,4 +37,14 @@ public class InetUtilsProperties {
 	 * List of Java regex expressions for network interfaces that will be ignored.
 	 */
 	private List<String> ignoredInterfaces = new ArrayList<>();
+
+	/**
+	 * Use only interfaces with site local addresses. See {@link InetAddress#isSiteLocalAddress()} for more details.
+	 */
+	private boolean useOnlySiteLocalInterfaces = false;
+
+	/**
+	 * List of Java regex expressions for network addresses that will be ignored.
+	 */
+	private List<String> preferredNetworks = new ArrayList<>();
 }

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

@@ -86,4 +86,36 @@ public void testDefaultIgnoreInterface() {
 		}
 	}
 
+	@Test
+	public void testSiteLocalAddresses() throws Exception {
+		InetUtilsProperties properties = new InetUtilsProperties();
+		properties.setUseOnlySiteLocalInterfaces(true);
+
+		try (InetUtils utils = new InetUtils(properties)) {
+			assertFalse(utils.ignoreAddress(InetAddress.getByName("192.168.0.1")));
+			assertTrue(utils.ignoreAddress(InetAddress.getByName("5.5.8.1")));
+		}
+	}
+
+	@Test
+	public void testPrefferedNetworksRegex() throws Exception {
+		InetUtilsProperties properties = new InetUtilsProperties();
+		properties.setPreferredNetworks(Arrays.asList("192.168.*"));
+
+	try (InetUtils utils = new InetUtils(properties)) {
+		assertTrue(utils.ignoreAddress(InetAddress.getByName("192.168.0.1")));
+		assertFalse(utils.ignoreAddress(InetAddress.getByName("5.5.8.1")));
+		}
+	}
+
+	@Test
+	public void testPrefferedNetworksSimple() throws Exception {
+		InetUtilsProperties properties = new InetUtilsProperties();
+		properties.setPreferredNetworks(Arrays.asList("192"));
+
+		try (InetUtils utils = new InetUtils(properties)) {
+			assertTrue(utils.ignoreAddress(InetAddress.getByName("192.168.0.1")));
+		assertFalse(utils.ignoreAddress(InetAddress.getByName("5.5.8.1")));
+		}
+	}
 }