[FIXED JENKINS-9230] Added unique instance identifier to UDP broadcast and DNS multicast.

changelog.html

@@ -65,6 +65,9 @@ Upcoming changes</a>
   <li class=bug>
     Fixed a persistence problem in <tt>View$PropertyList</tt>
     (<a href="http://issues.jenkins-ci.org/browse/JENKINS-9367">issue 9367</a>)
+  <li class=bug>
+    Added unique instance identifier to UDP broadcast and DNS multicast information.
+    (<a href="http://issues.jenkins-ci.org/browse/JENKINS-9230">issue 9230</a>)
   <li class=rfe>
     Maven agent needs a fix for the 'hardcoded' socket connection to localhost
     (<a href="http://issues.jenkins-ci.org/browse/JENKINS-6795">issue 6795</a>)

core/src/main/java/hudson/DNSMultiCast.java

 package hudson;
 
 import hudson.model.Hudson;
+import hudson.Util;
 
 import javax.jmdns.JmDNS;
 import javax.jmdns.ServiceInfo;
@@ -39,6 +40,8 @@ public class DNSMultiCast implements Closeable {
             if (tal!=null)
                 props.put("slave-port",String.valueOf(tal.getPort()));
 
+            props.put("server-id", Util.getDigestOf(hudson.getSecretKey()));
+
             jmdns.registerService(ServiceInfo.create("_hudson._tcp.local.","hudson",
                     80,0,0,props));	// for backward compatibility
             jmdns.registerService(ServiceInfo.create("_jenkins._tcp.local.","jenkins",

core/src/main/java/hudson/UDPBroadcastThread.java

@@ -25,6 +25,7 @@ package hudson;
 
 import hudson.model.Hudson;
 import hudson.util.OneShotEvent;
+import hudson.Util;
 
 import java.io.IOException;
 import java.net.BindException;
@@ -77,6 +78,7 @@ public class UDPBroadcastThread extends Thread {
                 StringBuilder rsp = new StringBuilder("<hudson>");
                 tag(rsp,"version",Hudson.VERSION);
                 tag(rsp,"url",hudson.getRootUrl());
+                tag(rsp,"server-id", Util.getDigestOf(hudson.getSecretKey()));
                 tag(rsp,"slave-port",tal==null?null:tal.getPort());
 
                 for (UDPBroadcastFragment f : UDPBroadcastFragment.all())