add unit tests fetching pod metrics and clean up code

Signed-off-by: Mengnan Gong <namco1992@gmail.com>

.changeset/wet-cameras-call.md

@@ -1,8 +1,10 @@
 ---
 '@backstage/plugin-kubernetes-backend': minor
-'@backstage/plugin-kubernetes-common': minor
+'@backstage/plugin-kubernetes-common': patch
 ---
 
 The Kubernetes errors when fetching pod metrics are now captured and returned to the frontend.
 
-Include the `PodStatusFetchResponse` into the `FetchResponse` union type. Now the method `fetchPodMetricsByNamespaces` accepts a set of namespaces and returns a `FetchResponseWrapper`, just like other public fetch methods in the fetcher.
+- **BREAKING** The method `fetchPodMetricsByNamespace` in the interface `KubernetesFetcher` is changed to `fetchPodMetricsByNamespaces`. It now accepts a set of namespace strings and returns `Promise<FetchResponseWrapper>`.
+- Add the `PodStatusFetchResponse` to the `FetchResponse` union type.
+- Add `NOT_FOUND` to the `KubernetesErrorTypes` union type, the HTTP error with status code 404 will be mapped to this error.

plugins/kubernetes-backend/src/service/KubernetesFanOutHandler.test.ts

@@ -675,6 +675,82 @@ describe('getKubernetesObjectsByEntity', () => {
       ],
     });
   });
+  it('retrieve objects for two clusters, one fails to fetch pod metrics', async () => {
+    getClustersByEntity.mockImplementation(() =>
+      Promise.resolve({
+        clusters: [
+          {
+            name: 'test-cluster',
+            authProvider: 'serviceAccount',
+            dashboardUrl: 'https://k8s.foo.coom',
+          },
+          {
+            name: 'other-cluster',
+            authProvider: 'google',
+          },
+        ],
+      }),
+    );
+
+    mockFetch(fetchObjectsForService);
+
+    // To simulate the partial failure, return a valid response for the first call,
+    // and an error for the second call.
+    fetchPodMetricsByNamespaces
+      .mockImplementationOnce(
+        (clusterDetails: ClusterDetails, namespaces: Set<string>) =>
+          Promise.resolve(generatePodStatus(clusterDetails.name, namespaces)),
+      )
+      .mockResolvedValueOnce({
+        errors: [
+          {
+            errorType: 'NOT_FOUND',
+            resourcePath: '/some/path',
+            statusCode: 404,
+          },
+        ],
+        responses: [],
+      });
+
+    const sut = getKubernetesFanOutHandler([]);
+
+    const result = await sut.getKubernetesObjectsByEntity({
+      entity,
+      auth: {
+        google: 'google_token_123',
+      },
+    });
+
+    expect(getClustersByEntity.mock.calls.length).toBe(1);
+    expect(fetchObjectsForService.mock.calls.length).toBe(2);
+    expect(result).toStrictEqual({
+      items: [
+        {
+          cluster: {
+            dashboardUrl: 'https://k8s.foo.coom',
+            name: 'test-cluster',
+          },
+          errors: [],
+          podMetrics: [POD_METRICS_FIXTURE],
+          resources: resourcesByCluster('test-cluster'),
+        },
+        {
+          cluster: {
+            name: 'other-cluster',
+          },
+          errors: [
+            {
+              errorType: 'NOT_FOUND',
+              resourcePath: '/some/path',
+              statusCode: 404,
+            },
+          ],
+          podMetrics: [],
+          resources: resourcesByCluster('other-cluster'),
+        },
+      ],
+    });
+  });
 });
 
 describe('getCustomResourcesByEntity', () => {

plugins/kubernetes-backend/src/service/KubernetesFanOutHandler.ts

@@ -358,7 +358,7 @@ export class KubernetesFanOutHandler {
       namespaces,
     );
 
-    result.errors.concat(podMetrics.errors);
+    result.errors.push(...podMetrics.errors);
     return [result, podMetrics.responses as PodStatusFetchResponse[]];
   }
 

plugins/kubernetes-backend/src/service/KubernetesFetcher.ts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { CoreV1Api, topPods } from '@kubernetes/client-node';
+import { topPods } from '@kubernetes/client-node';
 import lodash, { Dictionary } from 'lodash';
 import { Logger } from 'winston';
 import {
@@ -33,10 +33,6 @@ import {
 } from '@backstage/plugin-kubernetes-common';
 import { KubernetesClientProvider } from './KubernetesClientProvider';
 
-export interface Clients {
-  core: CoreV1Api;
-}
-
 export interface KubernetesClientBasedFetcherOptions {
   kubernetesClientProvider: KubernetesClientProvider;
   logger: Logger;
@@ -66,6 +62,8 @@ const statusCodeToErrorType = (statusCode: number): KubernetesErrorTypes => {
       return 'BAD_REQUEST';
     case 401:
       return 'UNAUTHORIZED_ERROR';
+    case 404:
+      return 'NOT_FOUND';
     case 500:
       return 'SYSTEM_ERROR';
     default:

plugins/kubernetes-common/api-report.md

@@ -179,6 +179,7 @@ export interface JobsFetchResponse {
 export type KubernetesErrorTypes =
   | 'BAD_REQUEST'
   | 'UNAUTHORIZED_ERROR'
+  | 'NOT_FOUND'
   | 'SYSTEM_ERROR'
   | 'UNKNOWN_ERROR';
 

plugins/kubernetes-common/src/types.ts

@@ -233,6 +233,7 @@ export interface KubernetesFetchError {
 export type KubernetesErrorTypes =
   | 'BAD_REQUEST'
   | 'UNAUTHORIZED_ERROR'
+  | 'NOT_FOUND'
   | 'SYSTEM_ERROR'
   | 'UNKNOWN_ERROR';