feat(kubernetes): update k8s-backend plugin to use label selectors

update plugin to use label selectors when querying backend

plugins/kubernetes/README.md

@@ -14,7 +14,12 @@ It is only meant for local development, and the setup for it can be found inside
 
 ## Surfacing your Kubernetes components as part of an entity
 
-### Adding the entity annotation
+There are 2 ways to surface your kubernetes components as part of an entity.
+The label selector takes precedence over the annotation/service id.
+
+### Common `backstage.io/kubernetes-id` label
+
+#### Adding the entity annotation
 
 In order for Backstage to detect that an entity has Kubernetes components,
 the following annotation should be added to the entity.
@@ -24,7 +29,7 @@ annotations:
   'backstage.io/kubernetes-id': dice-roller
 ```
 
-### Labeling Kubernetes components
+#### Labeling Kubernetes components
 
 In order for Kubernetes components to show up in the service catalog
 as a part of an entity, Kubernetes components must be labeled with the following label:
@@ -32,3 +37,19 @@ as a part of an entity, Kubernetes components must be labeled with the following
 ```yaml
 'backstage.io/kubernetes-id': <ENTITY_NAME>
 ```
+
+### Full label selector
+
+#### Adding the entity label selector to the spec
+
+In order for Backstage to detect that an entity has kubernetes components the `kubernetes.selector` must have a valid selector. (Currently only matchLabels is supported)
+
+```yaml
+spec:
+  kubernetes:
+    selector:
+      matchLabels:
+        someKey: someValue
+        other-key: other-value
+        app.kubernetes.io/name: dice-roller
+```

plugins/kubernetes/src/api/KubernetesBackendClient.ts

@@ -20,6 +20,7 @@ import {
   AuthRequestBody,
   ObjectsByServiceIdResponse,
 } from '@backstage/plugin-kubernetes-backend';
+import { V1LabelSelector } from '@kubernetes/client-node';
 
 export class KubernetesBackendClient implements KubernetesApi {
   private readonly discoveryApi: DiscoveryApi;
@@ -50,10 +51,23 @@ export class KubernetesBackendClient implements KubernetesApi {
     return await response.json();
   }
 
-  async getObjectsByServiceId(
+  private parseLabelSelector(params: V1LabelSelector): string {
+    // TODO: figure out how to convert the selector to the full query param from the yaml
+    //  (as shown here https://github.com/kubernetes/apimachinery/blob/master/pkg/labels/selector.go)
+    return Object.keys(params.matchLabels)
+      .map(key => `${key}=${params[key]}`)
+      .join(',');
+  }
+
+  async getObjectsByLabelSelector(
     serviceId: String,
+    labelSelector: V1LabelSelector,
     requestBody: AuthRequestBody,
   ): Promise<ObjectsByServiceIdResponse> {
-    return await this.getRequired(`/services/${serviceId}`, requestBody);
+    const labelSelectorQueryParams = this.parseLabelSelector(labelSelector);
+    return await this.getRequired(
+      `/services/${serviceId}?labelSelector=${labelSelectorQueryParams}`,
+      requestBody,
+    );
   }
 }

plugins/kubernetes/src/api/types.ts

@@ -19,6 +19,7 @@ import {
   AuthRequestBody,
   ObjectsByServiceIdResponse,
 } from '@backstage/plugin-kubernetes-backend';
+import { V1LabelSelector } from '@kubernetes/client-node';
 
 export const kubernetesApiRef = createApiRef<KubernetesApi>({
   id: 'plugin.kubernetes.service',
@@ -27,8 +28,9 @@ export const kubernetesApiRef = createApiRef<KubernetesApi>({
 });
 
 export interface KubernetesApi {
-  getObjectsByServiceId(
+  getObjectsByLabelSelector(
     serviceId: String,
+    labelSelector: V1LabelSelector,
     requestBody: AuthRequestBody,
   ): Promise<ObjectsByServiceIdResponse>;
 }

plugins/kubernetes/src/components/KubernetesContent/KubernetesContent.tsx

@@ -41,6 +41,7 @@ import {
   ExtensionsV1beta1Ingress,
   V1ConfigMap,
   V1HorizontalPodAutoscaler,
+  V1LabelSelector,
   V1Service,
 } from '@kubernetes/client-node';
 import { Services } from '../Services';
@@ -129,9 +130,27 @@ export const KubernetesContent = ({ entity }: KubernetesContentProps) => {
         );
       }
 
+      // decide label selector to search by defaulting to this label
+      let labelSelector: V1LabelSelector = {
+        matchLabels: {
+          'backstage.io/kubernetes-id': entity.metadata.name,
+        },
+      };
+
+      if (
+        entity.spec.kubernetes &&
+        (entity.spec.kubernetes.selector as V1LabelSelector)
+      ) {
+        labelSelector = entity.spec.kubernetes.selector;
+      }
+
       // TODO: Add validation on contents/format of requestBody
       kubernetesApi
-        .getObjectsByServiceId(entity.metadata.name, requestBody)
+        .getObjectsByLabelSelector(
+          entity.metadata.name,
+          labelSelector,
+          requestBody,
+        )
         .then(result => {
           setKubernetesObjects(result);
         })