feat(techdocs): add extension for setting build strategy

Signed-off-by: Phil Kuang <pkuang@factset.com>

plugins/techdocs-node/src/extensions.ts

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * 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 { createExtensionPoint } from '@backstage/backend-plugin-api';
+import { DocsBuildStrategy } from './techdocsTypes';
+
+/**
+ * Extension point type for setting a custom build strategy.
+ *
+ * @public
+ */
+export interface TechdocsBuildStrategyExtensionPoint {
+  setBuildStrategy(buildStrategy: DocsBuildStrategy): void;
+}
+
+/**
+ * Extension point for setting a custom build strategy.
+ *
+ * @public
+ */
+export const techdocsBuildStrategyExtensionPoint =
+  createExtensionPoint<TechdocsBuildStrategyExtensionPoint>({
+    id: 'techdocs.buildStrategy',
+  });

plugins/techdocs-node/src/index.ts

@@ -23,3 +23,7 @@
 export * from './stages';
 export * from './helpers';
 export * from './techdocsTypes';
+export {
+  techdocsBuildStrategyExtensionPoint,
+  type TechdocsBuildStrategyExtensionPoint,
+} from './extensions';

plugins/techdocs-node/src/techdocsTypes.ts

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import { Entity } from '@backstage/catalog-model';
 import { IndexableDocument } from '@backstage/plugin-search-common';
 
 /**
@@ -46,3 +47,21 @@ export interface TechDocsDocument extends IndexableDocument {
    */
   path: string;
 }
+
+/**
+ * Parameters passed to the shouldBuild method on the DocsBuildStrategy interface
+ *
+ * @public
+ */
+export type ShouldBuildParameters = {
+  entity: Entity;
+};
+
+/**
+ * A strategy for when to build TechDocs locally, and when to skip building TechDocs (allowing for an external build)
+ *
+ * @public
+ */
+export interface DocsBuildStrategy {
+  shouldBuild(params: ShouldBuildParameters): Promise<boolean>;
+}