feat(catalog): new kind LocationRef

plugins/catalog-backend/examples/locationref.yaml

@@ -0,0 +1,8 @@
+---
+apiVersion: backstage.io/v1beta1
+kind: LocationRef
+metadata:
+  name: location-1
+spec:
+  type: github
+  target: https://github.com/spotify/backstage/blob/master/plugins/catalog-backend/examples/example-components.yaml

plugins/catalog-backend/src/ingestion/LocationReaders.ts

@@ -26,6 +26,7 @@ import { AnnotateLocationEntityProcessor } from './processors/AnnotateLocationEn
 import { EntityPolicyProcessor } from './processors/EntityPolicyProcessor';
 import { FileReaderProcessor } from './processors/FileReaderProcessor';
 import { GithubReaderProcessor } from './processors/GithubReaderProcessor';
+import { LocationRefProcessor } from './processors/LocationRefProcessor';
 import * as result from './processors/results';
 import {
   LocationProcessor,
@@ -57,6 +58,7 @@ export class LocationReaders implements LocationReader {
       new GithubReaderProcessor(),
       new YamlProcessor(),
       new EntityPolicyProcessor(entityPolicy),
+      new LocationRefProcessor(),
       new AnnotateLocationEntityProcessor(),
     ];
   }

plugins/catalog-backend/src/ingestion/processors/LocationRefProcessor.ts

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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.
+ */
+
+import { Entity, LocationRef, LocationSpec } from '@backstage/catalog-model';
+import * as result from './results';
+import { LocationProcessor, LocationProcessorEmit } from './types';
+
+export class LocationRefProcessor implements LocationProcessor {
+  async processEntity(
+    entity: Entity,
+    _location: LocationSpec,
+    emit: LocationProcessorEmit,
+  ): Promise<Entity> {
+    if (entity.kind === 'LocationRef') {
+      const location = entity as LocationRef;
+      if (location.spec.target) {
+        emit(
+          result.location(
+            { type: location.spec.type, target: location.spec.target },
+            false,
+          ),
+        );
+      }
+      if (location.spec.targets) {
+        for (const target of location.spec.targets) {
+          emit(result.location({ type: location.spec.type, target }, false));
+        }
+      }
+    }
+
+    return entity;
+  }
+}