KNOX-2962 - Knox readiness check gateway-status endpoint should return the list of topologies for which it is waiting for

gateway-server/src/main/java/org/apache/knox/gateway/services/topology/impl/GatewayStatusService.java

@@ -45,12 +45,17 @@ public synchronized boolean status() {
       LOG.noTopologiesToCheck();
       return false;
     }
-    Set<String> missing = new HashSet<>(topologyNamesToCheck);
-    missing.removeAll(deployedTopologies);
+    Set<String> missing = pendingTopologies();
     LOG.checkingGatewayStatus(deployedTopologies, missing);
     return missing.isEmpty();
   }
 
+  public synchronized Set<String> pendingTopologies() {
+    Set<String> missing = new HashSet<>(topologyNamesToCheck);
+    missing.removeAll(deployedTopologies);
+    return missing;
+  }
+
   /**
    * The list of topologies (which will be used to check the gateway status.)
    * are either coming from the config or collected automatically.

gateway-server/src/test/java/org/apache/knox/gateway/services/topology/impl/GatewayStatusServiceTest.java

@@ -17,10 +17,12 @@
  */
 package org.apache.knox.gateway.services.topology.impl;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashSet;
 
 import org.apache.knox.gateway.config.GatewayConfig;
@@ -43,4 +45,20 @@ public void testReadyStatus() throws Exception {
     statusService.onTopologyReady("t2");
     assertTrue(statusService.status());
   }
+
+  @Test
+  public void testPendingTopologies() throws Exception {
+    GatewayStatusService statusService = new GatewayStatusService();
+    GatewayConfig config = EasyMock.createNiceMock(GatewayConfig.class);
+    statusService.init(config, null);
+    assertFalse(statusService.status());
+    EasyMock.expect(config.getHealthCheckTopologies()).andReturn(new HashSet<>(Arrays.asList("t1", "t2"))).anyTimes();
+    EasyMock.replay(config);
+    statusService.initTopologiesToCheck();
+    assertEquals(new HashSet<>(Arrays.asList("t1", "t2")), statusService.pendingTopologies());
+    statusService.onTopologyReady("t1");
+    assertEquals(new HashSet<>(Arrays.asList("t2")), statusService.pendingTopologies());
+    statusService.onTopologyReady("t2");
+    assertEquals(Collections.emptySet(), statusService.pendingTopologies());
+  }
 }

gateway-service-health/src/main/java/org/apache/knox/gateway/service/health/PingResource.java

@@ -101,7 +101,7 @@ public Response status() {
             .getAttribute(GatewayServices.GATEWAY_SERVICES_ATTRIBUTE);
     GatewayStatusService statusService = services.getService(ServiceType.GATEWAY_STATUS_SERVICE);
     try (PrintWriter writer = response.getWriter()) {
-      writer.println(statusService.status() ? OK : PENDING);
+      writer.println(statusService.status() ? OK : PENDING + ": " + statusService.pendingTopologies());
     } catch (IOException e) {
       log.logException("status", e);
       return Response.serverError().entity(String.format(Locale.ROOT, "Failed to reply correctly due to : %s ", e)).build();