WFLY-16383 mod_cluster: Do not register contexts when in suspend mode

mod_cluster/undertow/src/main/java/org/wildfly/mod_cluster/undertow/UndertowEventHandlerAdapterService.java

@@ -118,14 +118,17 @@ private Context createContext(String contextPath, Host host) {
     }
 
     private synchronized void onStart(Context context) {
-        ContainerEventHandler handler = this.configuration.getContainerEventHandler();
-
-        handler.add(context);
-
         State state = this.configuration.getSuspendController().getState();
 
-        // TODO break into onDeploymentAdd once implemented in Undertow
-        if(state == State.RUNNING) {
+        if (state == State.RUNNING) {
+            // Following handler calls result in context registration on the proxy side, which in turn results in
+            // the proxy starting to serve 503 responses for this context. We want to avoid context registration unless
+            // the server is in RUNNING state.
+            // During normal server startup, this block is skipped and the add() & start() handler calls are done later
+            // in the `#resume()` method.
+            ContainerEventHandler handler = this.configuration.getContainerEventHandler();
+            handler.add(context);
+            // TODO break into onDeploymentAdd once implemented in Undertow
             handler.start(context);
         }
 
@@ -202,8 +205,16 @@ public void suspended(ServerActivityCallback listener) {
 
     @Override
     public void resume() {
+        // This is run just before container enters RUNNING state - contexts need to be registered.
+        ContainerEventHandler handler = this.configuration.getContainerEventHandler();
         for (Context context : this.contexts) {
-            this.configuration.getContainerEventHandler().start(context);
+            handler.add(context);
+            handler.start(context);
+        }
+        // Proxy will not consider this node to be ready, until it receives a STATUS request - send it now to minimize
+        // time when the proxy serves 503.
+        for (Engine engine : this.server.getEngines()) {
+            this.configuration.getContainerEventHandler().status(engine);
         }
     }
 }

testsuite/integration/clustering/src/test/java/org/jboss/as/test/clustering/cluster/modcluster/StartWorkersInSuspendedModeTestCase.java

@@ -39,7 +39,6 @@
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
-import static org.jboss.as.controller.client.helpers.ClientConstants.ADDRESS;
 import static org.jboss.as.controller.client.helpers.ClientConstants.INCLUDE_RUNTIME;
 import static org.jboss.as.controller.client.helpers.ClientConstants.OUTCOME;
 import static org.jboss.as.controller.client.helpers.ClientConstants.READ_RESOURCE_OPERATION;
@@ -85,7 +84,6 @@ private void assertWorkerNodeContextIsStopped() throws Exception {
 
         ModelNode op = createOpNode("subsystem=undertow/configuration=filter/mod-cluster=load-balancer/balancer=mycluster/node=" + NODE_1,
                                     READ_RESOURCE_OPERATION);
-        op.get(ADDRESS).add("context", "/" + MODULE_NAME);
         op.get(RECURSIVE).set(true);
         op.get(INCLUDE_RUNTIME).set(true);
 
@@ -105,8 +103,11 @@ private void assertWorkerNodeContextIsStopped() throws Exception {
             Thread.sleep(100);
         }
 
-        Assert.assertEquals(SUCCESS, modelNode.get(OUTCOME).asString());
-        Assert.assertEquals("stopped", modelNode.get(RESULT).get(STATUS).asString());
+        Assert.assertEquals("Operation failed: " + modelNode.asString(),
+                SUCCESS, modelNode.get(OUTCOME).asString());
+        Assert.assertFalse("No contexts are expected to be registered by mod_cluster: "
+                        + modelNode.get(RESULT).get("context").asString(),
+                modelNode.get(RESULT).get("context").isDefined());
     }
 
     static class ServerSetupTask extends CLIServerSetupTask {