fix #5194: prevent NPEs when the APIResourceList is missing

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### 6.8-SNAPSHOT
 
 #### Bugs
+* Fix #5194: prevented NPEs due to timing issues with KubernetesClient.visitResources
 * Fix #5214: null values are omitted by default, which means custom resources by in large won't need JsonIncludes annotations.  The only time that is required is when null is to be preserved via @JsonInclude(value = Include.ALWAYS) on the relevant field.
 * Fix #5218: No export for `io.fabric8.tekton.triggers.internal.knative.pkg.apis.duck.v1beta1` in tekton v1beta1 triggers model
 * Fix #5224: Ensuring jetty sets the User-Agent header

kubernetes-client/src/main/java/io/fabric8/kubernetes/client/impl/KubernetesClientImpl.java

@@ -17,7 +17,9 @@
 
 import io.fabric8.kubernetes.api.model.APIGroup;
 import io.fabric8.kubernetes.api.model.APIGroupBuilder;
+import io.fabric8.kubernetes.api.model.APIGroupList;
 import io.fabric8.kubernetes.api.model.APIResource;
+import io.fabric8.kubernetes.api.model.APIResourceList;
 import io.fabric8.kubernetes.api.model.APIService;
 import io.fabric8.kubernetes.api.model.APIServiceList;
 import io.fabric8.kubernetes.api.model.Binding;
@@ -160,6 +162,8 @@
 import io.fabric8.kubernetes.client.utils.ApiVersionUtil;
 import io.fabric8.kubernetes.client.utils.KubernetesSerialization;
 import io.fabric8.kubernetes.client.utils.Utils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.InputStream;
 import java.util.ArrayList;
@@ -173,6 +177,8 @@
  */
 public class KubernetesClientImpl extends BaseClient implements NamespacedKubernetesClient {
 
+  public static final Logger logger = LoggerFactory.getLogger(KubernetesClientImpl.class);
+
   public static final String KUBERNETES_VERSION_ENDPOINT = "version";
 
   /**
@@ -730,7 +736,10 @@ public void visitResources(ApiVisitor visitor) {
         .withVersions(new GroupVersionForDiscoveryBuilder().withGroupVersion("v1").build()).build()))) {
       return; // user terminated
     }
-    visitGroups(visitor, getApiGroups().getGroups());
+    APIGroupList apiGroups = getApiGroups();
+    if (apiGroups != null) {
+      visitGroups(visitor, apiGroups.getGroups());
+    }
   }
 
   private boolean visitGroups(ApiVisitor visitor, List<APIGroup> groups) {
@@ -752,7 +761,14 @@ private boolean visitGroups(ApiVisitor visitor, List<APIGroup> groups) {
               case SKIP:
                 continue;
               case CONTINUE:
-                for (APIResource resource : this.getApiResources(groupVersion).getResources()) {
+                APIResourceList apiResources = this.getApiResources(groupVersion);
+                if (apiResources == null) {
+                  if (logger.isDebugEnabled()) {
+                    logger.debug("{} is discoverable, but is not yet populating an APIResource list", groupVersion);
+                  }
+                  continue;
+                }
+                for (APIResource resource : apiResources.getResources()) {
                   if (resource.getName().contains("/")) { // skip subresources
                     continue;
                   }

kubernetes-tests/src/test/java/io/fabric8/kubernetes/client/mock/VisitResourcesTest.java

@@ -0,0 +1,75 @@
+/**
+ * Copyright (C) 2015 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.fabric8.kubernetes.client.mock;
+
+import io.fabric8.kubernetes.api.model.APIResource;
+import io.fabric8.kubernetes.api.model.APIResourceListBuilder;
+import io.fabric8.kubernetes.api.model.GenericKubernetesResource;
+import io.fabric8.kubernetes.api.model.GenericKubernetesResourceList;
+import io.fabric8.kubernetes.client.ApiVisitor;
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.dsl.MixedOperation;
+import io.fabric8.kubernetes.client.dsl.Resource;
+import io.fabric8.kubernetes.client.server.mock.EnableKubernetesMockClient;
+import io.fabric8.kubernetes.client.server.mock.KubernetesMockServer;
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@EnableKubernetesMockClient
+class VisitResourcesTest {
+  private KubernetesMockServer server;
+  private KubernetesClient client;
+
+  @Test
+  void testMissingApiResourcesAndGroups() {
+    // api/v1 is missing
+    // apis is missing
+    // the following should still succeed
+    client.visitResources(new ApiVisitor() {
+
+      @Override
+      public ApiVisitResult visitResource(String group, String version, APIResource apiResource,
+          MixedOperation<GenericKubernetesResource, GenericKubernetesResourceList, Resource<GenericKubernetesResource>> operation) {
+        throw new AssertionError();
+      }
+    });
+  }
+
+  @Test
+  void testVisitResource() throws Exception {
+    CompletableFuture<APIResource> visited = new CompletableFuture<>();
+    server.expect().withPath("/api/v1").andReturn(200, new APIResourceListBuilder().addNewResource()
+        .withName("something")
+        .endResource().build()).always();
+    // the following should still succeed
+    client.visitResources(new ApiVisitor() {
+
+      @Override
+      public ApiVisitResult visitResource(String group, String version, APIResource apiResource,
+          MixedOperation<GenericKubernetesResource, GenericKubernetesResourceList, Resource<GenericKubernetesResource>> operation) {
+        visited.complete(apiResource);
+        return ApiVisitResult.CONTINUE;
+      }
+    });
+
+    assertEquals("something", visited.get(0, TimeUnit.MILLISECONDS).getName());
+  }
+}