[JENKINS-34705] - Prevent hanging of InstallationWizard if internet check is skipped (#2328)

core/src/main/java/hudson/model/UpdateCenter.java

@@ -197,6 +197,12 @@ public class UpdateCenter extends AbstractModelObject implements Saveable, OnMas
          * Connection status has not started yet.
          */
         PRECHECK,
+        /**
+         * Connection status check has been skipped.
+         * As example, it may happen if there is no connection check URL defined for the site.
+         * @since TODO
+         */
+        SKIPPED,
         /**
          * Connection status is being checked at this time.
          */
@@ -1378,6 +1384,10 @@ public class UpdateCenter extends AbstractModelObject implements Saveable, OnMas
                             connectionStates.put(ConnectionStatus.INTERNET, ConnectionStatus.OK);
                         }
                     });
+                } else {
+                    LOGGER.log(WARNING, "Update site '{0}' does not declare the connection check URL. "
+                            + "Skipping the network availability check.", site.getId());
+                    connectionStates.put(ConnectionStatus.INTERNET, ConnectionStatus.SKIPPED);
                 }
 
                 connectionStates.put(ConnectionStatus.UPDATE_SITE, ConnectionStatus.CHECKING);

core/src/main/java/hudson/model/UpdateSite.java

@@ -341,9 +341,11 @@ public class UpdateSite {
     }
 
     /**
-     * Returns an "always up" server for Internet connectivity testing, or null if we are going to skip the test.
+     * Gets a URL for the Internet connection check.
+     * @return  an "always up" server for Internet connectivity testing, or {@code null} if we are going to skip the test.
      */
     @Exported
+    @CheckForNull
     public String getConnectionCheckUrl() {
         Data dt = getData();
         if(dt==null)    return "http://www.google.com/";

war/src/main/js/util/jenkins.js

@@ -200,12 +200,17 @@ exports.testConnectivity = function(siteId, handler) {
 				handler(false, true, response.message);
 			}
 			
+			// Define statuses, which need additional check iteration via async job on the Jenkins master
+			// Statuses like "OK" or "SKIPPED" are considered as fine.
 			var uncheckedStatuses = ['PRECHECK', 'CHECKING', 'UNCHECKED'];
 			if(uncheckedStatuses.indexOf(response.data.updatesite) >= 0  || uncheckedStatuses.indexOf(response.data.internet) >= 0) {
 				setTimeout(testConnectivity, 100);
 			}
 			else {
-				if(response.status !== 'ok' || response.data.updatesite !== 'OK' || response.data.internet !== 'OK') {
+				// Update site should be always reachable, but we do not require the internet connection
+				// if it's explicitly skipped by the update center
+				if(response.status !== 'ok' || response.data.updatesite !== 'OK' || 
+							(response.data.internet !== 'OK' && response.data.internet !== 'SKIPPED')) {
 					// no connectivity, but not fatal
 					handler(false, false);
 				}