refactor kubernetes fetcher (#7504)

* refactor kubernetes fetcher Signed-off-by: mclarke47 <matthewclarke47@gmail.com> * typo Signed-off-by: mclarke47 <matthewclarke47@gmail.com> * tsc errors Signed-off-by: mclarke47 <matthewclarke47@gmail.com> * Create unlucky-laws-doubt.md Signed-off-by: mclarke47 <matthewclarke47@gmail.com> * missed prettier Signed-off-by: mclarke47 <matthewclarke47@gmail.com> * api report Signed-off-by: mclarke47 <matthewclarke47@gmail.com> * fix tests Signed-off-by: mclarke47 <matthewclarke47@gmail.com>
2021-10-11 15:38:37 +01:00
parent adf3c687b3
commit 89bcf90b66
7 changed files with 329 additions and 275 deletions
@@ -0,0 +1,6 @@
+---
+'@backstage/plugin-kubernetes-backend': patch
+'@backstage/plugin-kubernetes': patch
+---
+
+Refactor kubernetes fetcher to reduce boilerplate code
@@ -46,19 +46,15 @@ export function createRouter(options: RouterOptions): Promise<express.Router>;
 // Warning: (ae-missing-release-tag) "CustomResource" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
 //
 // @public (undocumented)
-export interface CustomResource {
+export interface CustomResource extends ObjectToFetch {
  // (undocumented)
-  apiVersion: string;
-  // (undocumented)
-  group: string;
-  // (undocumented)
-  plural: string;
+  objectType: 'customresources';
 }

 // Warning: (ae-missing-release-tag) "DEFAULT_OBJECTS" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
 //
 // @public (undocumented)
-export const DEFAULT_OBJECTS: KubernetesObjectTypes[];
+export const DEFAULT_OBJECTS: ObjectToFetch[];

 // Warning: (ae-missing-release-tag) "FetchResponseWrapper" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
 //
@@ -139,11 +135,25 @@ export interface ObjectFetchParams {
  // (undocumented)
  labelSelector: string;
  // (undocumented)
-  objectTypesToFetch: Set<KubernetesObjectTypes>;
+  objectTypesToFetch: Set<ObjectToFetch>;
  // (undocumented)
  serviceId: string;
 }

+// Warning: (ae-missing-release-tag) "ObjectToFetch" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
+//
+// @public (undocumented)
+export interface ObjectToFetch {
+  // (undocumented)
+  apiVersion: string;
+  // (undocumented)
+  group: string;
+  // (undocumented)
+  objectType: KubernetesObjectTypes;
+  // (undocumented)
+  plural: string;
+}
+
 // Warning: (ae-missing-release-tag) "RouterOptions" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
 //
 // @public (undocumented)
@@ -19,8 +19,8 @@ import {
  ClusterDetails,
  CustomResource,
  KubernetesFetcher,
-  KubernetesObjectTypes,
  KubernetesServiceLocator,
+  ObjectToFetch,
 } from '../types/types';
 import {
  ClusterObjects,
@@ -29,14 +29,49 @@ import {
 import { KubernetesAuthTranslator } from '../kubernetes-auth-translator/types';
 import { KubernetesAuthTranslatorGenerator } from '../kubernetes-auth-translator/KubernetesAuthTranslatorGenerator';

-export const DEFAULT_OBJECTS: KubernetesObjectTypes[] = [
-  'pods',
-  'services',
-  'configmaps',
-  'deployments',
-  'replicasets',
-  'horizontalpodautoscalers',
-  'ingresses',
+export const DEFAULT_OBJECTS: ObjectToFetch[] = [
+  {
+    group: '',
+    apiVersion: 'v1',
+    plural: 'pods',
+    objectType: 'pods',
+  },
+  {
+    group: '',
+    apiVersion: 'v1',
+    plural: 'services',
+    objectType: 'services',
+  },
+  {
+    group: '',
+    apiVersion: 'v1',
+    plural: 'configmaps',
+    objectType: 'configmaps',
+  },
+  {
+    group: 'apps',
+    apiVersion: 'v1',
+    plural: 'deployments',
+    objectType: 'deployments',
+  },
+  {
+    group: 'apps',
+    apiVersion: 'v1',
+    plural: 'replicasets',
+    objectType: 'replicasets',
+  },
+  {
+    group: 'autoscaling',
+    apiVersion: 'v1',
+    plural: 'horizontalpodautoscalers',
+    objectType: 'horizontalpodautoscalers',
+  },
+  {
+    group: 'networking.k8s.io',
+    apiVersion: 'v1',
+    plural: 'ingresses',
+    objectType: 'ingresses',
+  },
 ];

 export interface KubernetesFanOutHandlerOptions {
@@ -44,7 +79,7 @@ export interface KubernetesFanOutHandlerOptions {
  fetcher: KubernetesFetcher;
  serviceLocator: KubernetesServiceLocator;
  customResources: CustomResource[];
-  objectTypesToFetch?: KubernetesObjectTypes[];
+  objectTypesToFetch?: ObjectToFetch[];
 }

 export class KubernetesFanOutHandler {
@@ -52,7 +87,7 @@ export class KubernetesFanOutHandler {
  private readonly fetcher: KubernetesFetcher;
  private readonly serviceLocator: KubernetesServiceLocator;
  private readonly customResources: CustomResource[];
-  private readonly objectTypesToFetch: KubernetesObjectTypes[];
+  private readonly objectTypesToFetch: Set<ObjectToFetch>;

  constructor({
    logger,
@@ -65,7 +100,7 @@ export class KubernetesFanOutHandler {
    this.fetcher = fetcher;
    this.serviceLocator = serviceLocator;
    this.customResources = customResources;
-    this.objectTypesToFetch = objectTypesToFetch;
+    this.objectTypesToFetch = new Set(objectTypesToFetch);
  }

  async getKubernetesObjectsByEntity(requestBody: KubernetesRequestBody) {
@@ -109,7 +144,7 @@ export class KubernetesFanOutHandler {
          .fetchObjectsForService({
            serviceId: entityName,
            clusterDetails: clusterDetailsItem,
-            objectTypesToFetch: new Set(this.objectTypesToFetch),
+            objectTypesToFetch: this.objectTypesToFetch,
            labelSelector,
            customResources: this.customResources,
          })
@@ -16,6 +16,22 @@

 import { getVoidLogger } from '@backstage/backend-common';
 import { KubernetesClientBasedFetcher } from './KubernetesFetcher';
+import { ObjectToFetch } from '../types/types';
+
+const OBJECTS_TO_FETCH = new Set<ObjectToFetch>([
+  {
+    group: '',
+    apiVersion: 'v1',
+    plural: 'pods',
+    objectType: 'pods',
+  },
+  {
+    group: '',
+    apiVersion: 'v1',
+    plural: 'services',
+    objectType: 'services',
+  },
+]);

 describe('KubernetesFetcher', () => {
  let clientMock: any;
@@ -25,15 +41,11 @@ describe('KubernetesFetcher', () => {
  beforeEach(() => {
    jest.resetAllMocks();
    clientMock = {
-      listPodForAllNamespaces: jest.fn(),
-      listServiceForAllNamespaces: jest.fn(),
+      listClusterCustomObject: jest.fn(),
+      addInterceptor: jest.fn(),
    };

    kubernetesClientProvider = {
-      getCoreClientByClusterDetails: jest.fn(() => clientMock),
-      getAppsClientByClusterDetails: jest.fn(() => clientMock),
-      getAutoscalingClientByClusterDetails: jest.fn(() => clientMock),
-      getNetworkingBeta1Client: jest.fn(() => clientMock),
      getCustomObjectsClient: jest.fn(() => clientMock),
    };

@@ -44,7 +56,7 @@ describe('KubernetesFetcher', () => {
  });

  const testErrorResponse = async (errorResponse: any, expectedResult: any) => {
-    clientMock.listPodForAllNamespaces.mockResolvedValueOnce({
+    clientMock.listClusterCustomObject.mockResolvedValueOnce({
      body: {
        items: [
          {
@@ -56,7 +68,7 @@ describe('KubernetesFetcher', () => {
      },
    });

-    clientMock.listServiceForAllNamespaces.mockRejectedValue(errorResponse);
+    clientMock.listClusterCustomObject.mockRejectedValue(errorResponse);

    const result = await sut.fetchObjectsForService({
      serviceId: 'some-service',
@@ -66,7 +78,7 @@ describe('KubernetesFetcher', () => {
        serviceAccountToken: 'token',
        authProvider: 'serviceAccount',
      },
-      objectTypesToFetch: new Set(['pods', 'services']),
+      objectTypesToFetch: OBJECTS_TO_FETCH,
      labelSelector: '',
      customResources: [],
    });
@@ -87,19 +99,35 @@ describe('KubernetesFetcher', () => {
      ],
    });

-    expect(clientMock.listPodForAllNamespaces.mock.calls.length).toBe(1);
-    expect(clientMock.listServiceForAllNamespaces.mock.calls.length).toBe(1);
+    expect(clientMock.listClusterCustomObject.mock.calls.length).toBe(2);
+
+    expect(clientMock.listClusterCustomObject.mock.calls[0]).toEqual([
+      '',
+      'v1',
+      'pods',
+      '',
+      '',
+      '',
+      'backstage.io/kubernetes-id=some-service',
+    ]);
+
+    expect(clientMock.listClusterCustomObject.mock.calls[1]).toEqual([
+      '',
+      'v1',
+      'services',
+      '',
+      '',
+      '',
+      'backstage.io/kubernetes-id=some-service',
+    ]);

    expect(
-      kubernetesClientProvider.getAppsClientByClusterDetails.mock.calls.length,
-    ).toBe(2);
-    expect(
-      kubernetesClientProvider.getCoreClientByClusterDetails.mock.calls.length,
+      kubernetesClientProvider.getCustomObjectsClient.mock.calls.length,
    ).toBe(2);
  };

  it('should return pods, services', async () => {
-    clientMock.listPodForAllNamespaces.mockResolvedValueOnce({
+    clientMock.listClusterCustomObject.mockResolvedValueOnce({
      body: {
        items: [
          {
@@ -111,7 +139,7 @@ describe('KubernetesFetcher', () => {
      },
    });

-    clientMock.listServiceForAllNamespaces.mockResolvedValueOnce({
+    clientMock.listClusterCustomObject.mockResolvedValueOnce({
      body: {
        items: [
          {
@@ -131,7 +159,7 @@ describe('KubernetesFetcher', () => {
        serviceAccountToken: 'token',
        authProvider: 'serviceAccount',
      },
-      objectTypesToFetch: new Set(['pods', 'services']),
+      objectTypesToFetch: OBJECTS_TO_FETCH,
      labelSelector: '',
      customResources: [],
    });
@@ -162,41 +190,160 @@ describe('KubernetesFetcher', () => {
      ],
    });

-    expect(clientMock.listPodForAllNamespaces.mock.calls.length).toBe(1);
-    expect(clientMock.listServiceForAllNamespaces.mock.calls.length).toBe(1);
+    expect(clientMock.listClusterCustomObject.mock.calls.length).toBe(2);
+
+    expect(clientMock.listClusterCustomObject.mock.calls[0]).toEqual([
+      '',
+      'v1',
+      'pods',
+      '',
+      '',
+      '',
+      'backstage.io/kubernetes-id=some-service',
+    ]);
+
+    expect(clientMock.listClusterCustomObject.mock.calls[1]).toEqual([
+      '',
+      'v1',
+      'services',
+      '',
+      '',
+      '',
+      'backstage.io/kubernetes-id=some-service',
+    ]);

    expect(
-      kubernetesClientProvider.getAppsClientByClusterDetails.mock.calls.length,
-    ).toBe(2);
-    expect(
-      kubernetesClientProvider.getCoreClientByClusterDetails.mock.calls.length,
+      kubernetesClientProvider.getCustomObjectsClient.mock.calls.length,
    ).toBe(2);
  });
-  it('should throw error on unknown type', () => {
-    expect(() =>
-      sut.fetchObjectsForService({
-        serviceId: 'some-service',
-        clusterDetails: {
-          name: 'cluster1',
-          url: 'http://localhost:9999',
-          serviceAccountToken: 'token',
-          authProvider: 'serviceAccount',
+  it('should return pods, services and customobjects', async () => {
+    clientMock.listClusterCustomObject.mockResolvedValueOnce({
+      body: {
+        items: [
+          {
+            metadata: {
+              name: 'pod-name',
+            },
+          },
+        ],
+      },
+    });
+
+    clientMock.listClusterCustomObject.mockResolvedValueOnce({
+      body: {
+        items: [
+          {
+            metadata: {
+              name: 'service-name',
+            },
+          },
+        ],
+      },
+    });
+
+    clientMock.listClusterCustomObject.mockResolvedValueOnce({
+      body: {
+        items: [
+          {
+            metadata: {
+              name: 'something-else',
+            },
+          },
+        ],
+      },
+    });
+
+    const result = await sut.fetchObjectsForService({
+      serviceId: 'some-service',
+      clusterDetails: {
+        name: 'cluster1',
+        url: 'http://localhost:9999',
+        serviceAccountToken: 'token',
+        authProvider: 'serviceAccount',
+      },
+      objectTypesToFetch: OBJECTS_TO_FETCH,
+      labelSelector: '',
+      customResources: [
+        {
+          objectType: 'customresources',
+          group: 'some-group',
+          apiVersion: 'v2',
+          plural: 'things',
        },
-        objectTypesToFetch: new Set<any>(['foo']),
-        labelSelector: '',
-        customResources: [],
-      }),
-    ).toThrow('unrecognised type=foo');
+      ],
+    });

-    expect(clientMock.listPodForAllNamespaces.mock.calls.length).toBe(0);
-    expect(clientMock.listServiceForAllNamespaces.mock.calls.length).toBe(0);
+    expect(result).toStrictEqual({
+      errors: [],
+      responses: [
+        {
+          type: 'pods',
+          resources: [
+            {
+              metadata: {
+                name: 'pod-name',
+              },
+            },
+          ],
+        },
+        {
+          type: 'services',
+          resources: [
+            {
+              metadata: {
+                name: 'service-name',
+              },
+            },
+          ],
+        },
+        {
+          type: 'customresources',
+          resources: [
+            {
+              metadata: {
+                name: 'something-else',
+              },
+            },
+          ],
+        },
+      ],
+    });
+
+    expect(clientMock.listClusterCustomObject.mock.calls.length).toBe(3);
+
+    expect(clientMock.listClusterCustomObject.mock.calls[0]).toEqual([
+      '',
+      'v1',
+      'pods',
+      '',
+      '',
+      '',
+      'backstage.io/kubernetes-id=some-service',
+    ]);
+
+    expect(clientMock.listClusterCustomObject.mock.calls[1]).toEqual([
+      '',
+      'v1',
+      'services',
+      '',
+      '',
+      '',
+      'backstage.io/kubernetes-id=some-service',
+    ]);
+
+    expect(clientMock.listClusterCustomObject.mock.calls[2]).toEqual([
+      'some-group',
+      'v2',
+      'things',
+      '',
+      '',
+      '',
+      'backstage.io/kubernetes-id=some-service',
+    ]);

    expect(
-      kubernetesClientProvider.getAppsClientByClusterDetails.mock.calls.length,
-    ).toBe(0);
-    expect(
-      kubernetesClientProvider.getCoreClientByClusterDetails.mock.calls.length,
-    ).toBe(0);
+      kubernetesClientProvider.getCustomObjectsClient.mock.calls.length,
+    ).toBe(3);
  });
  // they're in testErrorResponse
  // eslint-disable-next-line jest/expect-expect
@@ -283,7 +430,7 @@ describe('KubernetesFetcher', () => {
    );
  });
  it('should always add a labelSelector query', async () => {
-    clientMock.listPodForAllNamespaces.mockResolvedValueOnce({
+    clientMock.listClusterCustomObject.mockResolvedValueOnce({
      body: {
        items: [
          {
@@ -295,7 +442,7 @@ describe('KubernetesFetcher', () => {
      },
    });

-    clientMock.listServiceForAllNamespaces.mockResolvedValueOnce({
+    clientMock.listClusterCustomObject.mockResolvedValueOnce({
      body: {
        items: [
          {
@@ -315,12 +462,12 @@ describe('KubernetesFetcher', () => {
        serviceAccountToken: 'token',
        authProvider: 'serviceAccount',
      },
-      objectTypesToFetch: new Set(['pods', 'services']),
+      objectTypesToFetch: OBJECTS_TO_FETCH,
      labelSelector: '',
      customResources: [],
    });

-    const mockCall = clientMock.listPodForAllNamespaces.mock.calls[0];
+    const mockCall = clientMock.listClusterCustomObject.mock.calls[0];
    const actualSelector = mockCall[mockCall.length - 1];
    const expectedSelector = 'backstage.io/kubernetes-id=some-service';
    expect(actualSelector).toBe(expectedSelector);
@@ -18,16 +18,8 @@ import {
  AppsV1Api,
  AutoscalingV1Api,
  CoreV1Api,
-  ExtensionsV1beta1Ingress,
  NetworkingV1beta1Api,
-  V1ConfigMap,
-  V1Deployment,
-  V1HorizontalPodAutoscaler,
-  V1Pod,
-  V1ReplicaSet,
 } from '@kubernetes/client-node';
-import { V1Service } from '@kubernetes/client-node/dist/gen/model/v1Service';
-import http from 'http';
 import lodash, { Dictionary } from 'lodash';
 import { Logger } from 'winston';
 import {
@@ -36,7 +28,7 @@ import {
  KubernetesFetcher,
  KubernetesObjectTypes,
  ObjectFetchParams,
-  CustomResource,
+  ObjectToFetch,
 } from '../types/types';
 import {
  FetchResponse,
@@ -88,17 +80,6 @@ const statusCodeToErrorType = (statusCode: number): KubernetesErrorTypes => {
  }
 };

-const captureKubernetesErrorsRethrowOthers = (e: any): KubernetesFetchError => {
-  if (e.response && e.response.statusCode) {
-    return {
-      errorType: statusCodeToErrorType(e.response.statusCode),
-      statusCode: e.response.statusCode,
-      resourcePath: e.response.request.uri.pathname,
-    };
-  }
-  throw e;
-};
-
 export class KubernetesClientBasedFetcher implements KubernetesFetcher {
  private readonly kubernetesClientProvider: KubernetesClientProvider;
  private readonly logger: Logger;
@@ -114,202 +95,60 @@ export class KubernetesClientBasedFetcher implements KubernetesFetcher {
  fetchObjectsForService(
    params: ObjectFetchParams,
  ): Promise<FetchResponseWrapper> {
-    const fetchResults = Array.from(params.objectTypesToFetch).map(type => {
-      return this.fetchByObjectType(
-        params.clusterDetails,
-        type,
-        params.labelSelector ||
-          `backstage.io/kubernetes-id=${params.serviceId}`,
-      ).catch(captureKubernetesErrorsRethrowOthers);
-    });
+    const fetchResults = Array.from(params.objectTypesToFetch)
+      .concat(params.customResources)
+      .map(toFetch => {
+        return this.fetchResource(
+          params.clusterDetails,
+          toFetch,
+          params.labelSelector ||
+            `backstage.io/kubernetes-id=${params.serviceId}`,
+          toFetch.objectType,
+        ).catch(this.captureKubernetesErrorsRethrowOthers.bind(this));
+      });

-    const customObjectsFetchResults = params.customResources.map(cr => {
-      return this.fetchCustomResource(
-        params.clusterDetails,
-        cr,
-        params.labelSelector ||
-          `backstage.io/kubernetes-id=${params.serviceId}`,
-      ).catch(captureKubernetesErrorsRethrowOthers);
-    });
-
-    return Promise.all(fetchResults.concat(customObjectsFetchResults)).then(
-      fetchResultsToResponseWrapper,
-    );
+    return Promise.all(fetchResults).then(fetchResultsToResponseWrapper);
  }

-  // TODO could probably do with a tidy up
-  private fetchByObjectType(
-    clusterDetails: ClusterDetails,
-    type: KubernetesObjectTypes,
-    labelSelector: string,
-  ): Promise<FetchResponse> {
-    switch (type) {
-      case 'pods':
-        return this.fetchPodsForService(clusterDetails, labelSelector).then(
-          r => ({
-            type: type,
-            resources: r,
-          }),
-        );
-      case 'configmaps':
-        return this.fetchConfigMapsForService(
-          clusterDetails,
-          labelSelector,
-        ).then(r => ({ type: type, resources: r }));
-      case 'deployments':
-        return this.fetchDeploymentsForService(
-          clusterDetails,
-          labelSelector,
-        ).then(r => ({ type: type, resources: r }));
-      case 'replicasets':
-        return this.fetchReplicaSetsForService(
-          clusterDetails,
-          labelSelector,
-        ).then(r => ({ type: type, resources: r }));
-      case 'services':
-        return this.fetchServicesForService(clusterDetails, labelSelector).then(
-          r => ({ type: type, resources: r }),
-        );
-      case 'horizontalpodautoscalers':
-        return this.fetchHorizontalPodAutoscalersForService(
-          clusterDetails,
-          labelSelector,
-        ).then(r => ({ type: type, resources: r }));
-      case 'ingresses':
-        return this.fetchIngressesForService(
-          clusterDetails,
-          labelSelector,
-        ).then(r => ({ type: type, resources: r }));
-      default:
-        // unrecognised type
-        throw new Error(`unrecognised type=${type}`);
+  private captureKubernetesErrorsRethrowOthers(e: any): KubernetesFetchError {
+    if (e.response && e.response.statusCode) {
+      this.logger.info(
+        `statusCode=${e.response.statusCode} for resource ${e.response.request.uri.pathname}`,
+      );
+      return {
+        errorType: statusCodeToErrorType(e.response.statusCode),
+        statusCode: e.response.statusCode,
+        resourcePath: e.response.request.uri.pathname,
+      };
    }
+    throw e;
  }

-  private fetchCustomResource(
+  private fetchResource(
    clusterDetails: ClusterDetails,
-    customResource: CustomResource,
+    resource: ObjectToFetch,
    labelSelector: string,
+    objectType: KubernetesObjectTypes,
  ): Promise<FetchResponse> {
    const customObjects =
      this.kubernetesClientProvider.getCustomObjectsClient(clusterDetails);

+    customObjects.addInterceptor((requestOptions: any) => {
+      requestOptions.uri = requestOptions.uri.replace('/apis//v1/', '/api/v1/');
+    });
+
    return customObjects
      .listClusterCustomObject(
-        customResource.group,
-        customResource.apiVersion,
-        customResource.plural,
+        resource.group,
+        resource.apiVersion,
+        resource.plural,
        '',
        '',
        '',
        labelSelector,
      )
      .then(r => {
-        return { type: 'customresources', resources: (r.body as any).items };
+        return { type: objectType, resources: (r.body as any).items };
      });
  }
-
-  private singleClusterFetch<T>(
-    clusterDetails: ClusterDetails,
-    fn: (
-      client: Clients,
-    ) => Promise<{ body: { items: Array<T> }; response: http.IncomingMessage }>,
-  ): Promise<Array<T>> {
-    const core =
-      this.kubernetesClientProvider.getCoreClientByClusterDetails(
-        clusterDetails,
-      );
-    const apps =
-      this.kubernetesClientProvider.getAppsClientByClusterDetails(
-        clusterDetails,
-      );
-    const autoscaling =
-      this.kubernetesClientProvider.getAutoscalingClientByClusterDetails(
-        clusterDetails,
-      );
-    const networkingBeta1 =
-      this.kubernetesClientProvider.getNetworkingBeta1Client(clusterDetails);
-
-    this.logger.debug(`calling cluster=${clusterDetails.name}`);
-    return fn({ core, apps, autoscaling, networkingBeta1 }).then(({ body }) => {
-      return body.items;
-    });
-  }
-
-  private fetchServicesForService(
-    clusterDetails: ClusterDetails,
-    labelSelector: string,
-  ): Promise<Array<V1Service>> {
-    return this.singleClusterFetch<V1Service>(clusterDetails, ({ core }) =>
-      core.listServiceForAllNamespaces(false, '', '', labelSelector),
-    );
-  }
-
-  private fetchPodsForService(
-    clusterDetails: ClusterDetails,
-    labelSelector: string,
-  ): Promise<Array<V1Pod>> {
-    return this.singleClusterFetch<V1Pod>(clusterDetails, ({ core }) =>
-      core.listPodForAllNamespaces(false, '', '', labelSelector),
-    );
-  }
-
-  private fetchConfigMapsForService(
-    clusterDetails: ClusterDetails,
-    labelSelector: string,
-  ): Promise<Array<V1ConfigMap>> {
-    return this.singleClusterFetch<V1Pod>(clusterDetails, ({ core }) =>
-      core.listConfigMapForAllNamespaces(false, '', '', labelSelector),
-    );
-  }
-
-  private fetchDeploymentsForService(
-    clusterDetails: ClusterDetails,
-    labelSelector: string,
-  ): Promise<Array<V1Deployment>> {
-    return this.singleClusterFetch<V1Deployment>(clusterDetails, ({ apps }) =>
-      apps.listDeploymentForAllNamespaces(false, '', '', labelSelector),
-    );
-  }
-
-  private fetchReplicaSetsForService(
-    clusterDetails: ClusterDetails,
-    labelSelector: string,
-  ): Promise<Array<V1ReplicaSet>> {
-    return this.singleClusterFetch<V1ReplicaSet>(clusterDetails, ({ apps }) =>
-      apps.listReplicaSetForAllNamespaces(false, '', '', labelSelector),
-    );
-  }
-
-  private fetchHorizontalPodAutoscalersForService(
-    clusterDetails: ClusterDetails,
-    labelSelector: string,
-  ): Promise<Array<V1HorizontalPodAutoscaler>> {
-    return this.singleClusterFetch<V1HorizontalPodAutoscaler>(
-      clusterDetails,
-      ({ autoscaling }) =>
-        autoscaling.listHorizontalPodAutoscalerForAllNamespaces(
-          false,
-          '',
-          '',
-          labelSelector,
-        ),
-    );
-  }
-
-  private fetchIngressesForService(
-    clusterDetails: ClusterDetails,
-    labelSelector: string,
-  ): Promise<Array<ExtensionsV1beta1Ingress>> {
-    return this.singleClusterFetch<ExtensionsV1beta1Ingress>(
-      clusterDetails,
-      ({ networkingBeta1 }) =>
-        networkingBeta1.listIngressForAllNamespaces(
-          false,
-          '',
-          '',
-          labelSelector,
-        ),
-    );
-  }
 }
@@ -30,7 +30,10 @@ import {
 } from '../types/types';
 import { KubernetesRequestBody } from '@backstage/plugin-kubernetes-common';
 import { KubernetesClientProvider } from './KubernetesClientProvider';
-import { KubernetesFanOutHandler } from './KubernetesFanOutHandler';
+import {
+  KubernetesFanOutHandler,
+  DEFAULT_OBJECTS,
+} from './KubernetesFanOutHandler';
 import { KubernetesClientBasedFetcher } from './KubernetesFetcher';

 export interface RouterOptions {
@@ -109,6 +112,7 @@ export async function createRouter(
        group: c.getString('group'),
        apiVersion: c.getString('apiVersion'),
        plural: c.getString('plural'),
+        objectType: 'customresources',
      } as CustomResource),
  );

@@ -134,10 +138,18 @@ export async function createRouter(
  );

  const serviceLocator = getServiceLocator(options.config, clusterDetails);
-  const objectTypesToFetch = options.config.getOptionalStringArray(
+  const objectTypesToFetchStrings = options.config.getOptionalStringArray(
    'kubernetes.objectTypes',
  ) as KubernetesObjectTypes[];

+  let objectTypesToFetch;
+
+  if (objectTypesToFetchStrings) {
+    objectTypesToFetch = DEFAULT_OBJECTS.filter(obj =>
+      objectTypesToFetchStrings.includes(obj.objectType),
+    );
+  }
+
  const kubernetesFanOutHandler = new KubernetesFanOutHandler({
    logger,
    fetcher,
@@ -19,12 +19,6 @@ import type {
  KubernetesFetchError,
 } from '@backstage/plugin-kubernetes-common';

-export interface CustomResource {
-  group: string;
-  apiVersion: string;
-  plural: string;
-}
-
 export interface ObjectFetchParams {
  serviceId: string;
  clusterDetails:
@@ -32,7 +26,7 @@ export interface ObjectFetchParams {
    | GKEClusterDetails
    | ServiceAccountClusterDetails
    | ClusterDetails;
-  objectTypesToFetch: Set<KubernetesObjectTypes>;
+  objectTypesToFetch: Set<ObjectToFetch>;
  labelSelector: string;
  customResources: CustomResource[];
 }
@@ -52,6 +46,17 @@ export interface FetchResponseWrapper {

 // TODO fairly sure there's a easier way to do this

+export interface ObjectToFetch {
+  objectType: KubernetesObjectTypes;
+  group: string;
+  apiVersion: string;
+  plural: string;
+}
+
+export interface CustomResource extends ObjectToFetch {
+  objectType: 'customresources';
+}
+
 export type KubernetesObjectTypes =
  | 'pods'
  | 'services'