Make Kubernetes clusters refreshable

To make it possible to refresh Kubernetes clusters responsible all places that used ClusterDetails[] before now use the KubernetesClustersSupplier directly and call getClusters() on it. This allows people to use implement custom KubernetesClustersSuppliers that fetch the clusters from somewhere and refresh them using whatever mechanism they might need. Signed-off-by: Luna Stadler <luc@spreadshirt.net>
2022-03-24 15:37:33 +01:00
parent e82483f20b
commit 3d45427666
7 changed files with 179 additions and 44 deletions
@@ -261,6 +261,12 @@ Kubernetes plugin.

 Defaults to `false`.

+#### Custom `KubernetesClustersSupplier`
+
+If the configuration-based cluster locators do not work for your use-case,
+it is also possible to implement a
+[custom `KubernetesClustersSupplier`](installation.md#custom-cluster-discovery).
+
 ### `customResources` (optional)

 Configures which [custom resources][3] to look for when returning an entity's
@@ -90,6 +90,65 @@ async function main() {
 That's it! The Kubernetes frontend and backend have now been added to your
 Backstage app.

+### Custom cluster discovery
+
+If either existing
+[cluster locators](https://backstage.io/docs/features/kubernetes/configuration#clusterlocatormethods)
+don't work for your use-case, it is possible to implement a custom
+[KubernetesClustersSupplier](https://backstage.io/docs/reference/plugin-kubernetes-backend.kubernetesclusterssupplier).
+
+Change the following in `packages/backend/src/plugin/kubernetes.ts`:
+
+```diff
+-import { KubernetesBuilder } from '@backstage/plugin-kubernetes-backend';
+import {
+  ClusterDetails,
+  KubernetesBuilder,
+  KubernetesClustersSupplier,
+} from '@backstage/plugin-kubernetes-backend';
+ import { Router } from 'express';
+ import { PluginEnvironment } from '../types';
+import { Duration } from 'luxon';
+
+export class CustomClustersSupplier implements KubernetesClustersSupplier {
+  private clusterDetails: ClusterDetails[] = [];
+
+  async retrieveClusters() {
+    this.clusterDetails = []; // fetch from somewhere
+  }
+
+  async getClusters(): Promise<ClusterDetails[]> {
+    return this.clusterDetails;
+  }
+}
+
+ export default async function createPlugin(
+   env: PluginEnvironment,
+ ): Promise<Router> {
+-  const { router } = await KubernetesBuilder.createBuilder({
+  const builder = await KubernetesBuilder.createBuilder({
+     logger: env.logger,
+     config: env.config,
+-  }).build();
+  });
+
+  const clusterSupplier = new CustomClustersSupplier();
+  env.scheduler
+    .createScheduledTaskRunner({
+      frequency: Duration.fromObject({ minutes: 60 }),
+      timeout: Duration.fromObject({ minutes: 15 }),
+    })
+    .run({
+      id: 'refresh-kubernetes-clusters',
+      fn: clusterSupplier.retrieveClusters,
+    });
+  builder.setClusterSupplier(clusterSupplier);
+
+  const { router } = await builder.build();
+   return router;
+ }
+```
+
 ## Running Backstage locally

 Start the frontend and the backend app by