Fix NPE in cluster state collector for monitoring. (elastic#52371)

Take into account a null license may be returned by the license service.

Closes elastic#52317

Author: martijnvg

x-pack/plugin/monitoring/src/main/java/org/elasticsearch/xpack/monitoring/collector/cluster/ClusterStatsCollector.java

@@ -105,7 +105,8 @@ protected Collection<MonitoringDoc> doCollect(final MonitoringDoc.Node node,
         final List<XPackFeatureSet.Usage> xpackUsage = collect(usageSupplier);
         final boolean apmIndicesExist = doAPMIndicesExist(clusterState);
         // if they have any other type of license, then they are either okay or already know
-        final boolean clusterNeedsTLSEnabled = license.operationMode() == License.OperationMode.TRIAL &&
+        final boolean clusterNeedsTLSEnabled = license != null &&
+                                               license.operationMode() == License.OperationMode.TRIAL &&
                                                settings.hasValue(SECURITY_ENABLED.getKey()) &&
                                                SECURITY_ENABLED.get(settings) &&
                                                TRANSPORT_SSL_ENABLED.get(settings) == false;

x-pack/plugin/monitoring/src/test/java/org/elasticsearch/xpack/monitoring/collector/cluster/ClusterStatsCollectorTests.java

@@ -260,4 +260,64 @@ public void testDoCollect() throws Exception {
         verify(clusterAdminClient).prepareClusterStats();
         verify(client).execute(same(XPackUsageAction.INSTANCE), any(XPackUsageRequest.class));
     }
+
+    public void testDoCollectNoLicense() throws Exception {
+        final TimeValue timeout;
+        {
+            final String clusterName = randomAlphaOfLength(10);
+            whenClusterStateWithName(clusterName);
+            final String clusterUUID = UUID.randomUUID().toString();
+            whenClusterStateWithUUID(clusterUUID);
+            timeout = TimeValue.timeValueSeconds(randomIntBetween(1, 120));
+            withCollectionTimeout(ClusterStatsCollector.CLUSTER_STATS_TIMEOUT, timeout);
+        }
+        final IndexNameExpressionResolver indexNameExpressionResolver;
+        {
+            indexNameExpressionResolver = mock(IndexNameExpressionResolver.class);
+            when(indexNameExpressionResolver.concreteIndices(clusterState, IndicesOptions.lenientExpandOpen(), "apm-*"))
+                .thenReturn(new Index[0]);
+        }
+
+        final Client client = mock(Client.class);
+        {
+            final ClusterStatsResponse mockClusterStatsResponse = mock(ClusterStatsResponse.class);
+            final ClusterHealthStatus clusterStatus = randomFrom(ClusterHealthStatus.values());
+            when(mockClusterStatsResponse.getStatus()).thenReturn(clusterStatus);
+            when(mockClusterStatsResponse.getNodesStats()).thenReturn(mock(ClusterStatsNodes.class));
+
+            final ClusterStatsIndices mockClusterStatsIndices = mock(ClusterStatsIndices.class);
+
+            when(mockClusterStatsIndices.getIndexCount()).thenReturn(0);
+            when(mockClusterStatsResponse.getIndicesStats()).thenReturn(mockClusterStatsIndices);
+
+            final ClusterStatsRequestBuilder clusterStatsRequestBuilder = mock(ClusterStatsRequestBuilder.class);
+            when(clusterStatsRequestBuilder.get(eq(timeout))).thenReturn(mockClusterStatsResponse);
+
+            final ClusterAdminClient clusterAdminClient = mock(ClusterAdminClient.class);
+            when(clusterAdminClient.prepareClusterStats()).thenReturn(clusterStatsRequestBuilder);
+
+            final AdminClient adminClient = mock(AdminClient.class);
+            when(adminClient.cluster()).thenReturn(clusterAdminClient);
+            when(client.admin()).thenReturn(adminClient);
+
+            final XPackUsageResponse xPackUsageResponse = new XPackUsageResponse(
+                singletonList(new MonitoringFeatureSetUsage(true, true, false, null)));
+            @SuppressWarnings("unchecked")
+            final ActionFuture<XPackUsageResponse> xPackUsageFuture = (ActionFuture<XPackUsageResponse>) mock(ActionFuture.class);
+            when(client.execute(same(XPackUsageAction.INSTANCE), any(XPackUsageRequest.class))).thenReturn(xPackUsageFuture);
+            when(xPackUsageFuture.actionGet()).thenReturn(xPackUsageResponse);
+        }
+
+        final long interval = randomNonNegativeLong();
+        final Settings.Builder settings = Settings.builder();
+        final MonitoringDoc.Node node = MonitoringTestUtils.randomMonitoringNode(random());
+
+        final ClusterStatsCollector collector =
+            new ClusterStatsCollector(settings.build(), clusterService, licenseState,
+                client, licenseService, indexNameExpressionResolver);
+        final Collection<MonitoringDoc> results = collector.doCollect(node, interval, clusterState);
+        assertEquals(1, results.size());
+        final ClusterStatsMonitoringDoc doc = (ClusterStatsMonitoringDoc) results.iterator().next();
+        assertThat(doc.getLicense(), nullValue());
+    }
 }