[backend] use common error types

plugins/inventory-backend/package.json

@@ -21,6 +21,7 @@
     "compression": "^1.7.4",
     "cors": "^2.8.5",
     "express": "^4.17.1",
+    "express-promise-router": "^3.0.3",
     "helmet": "^3.22.0",
     "morgan": "^1.10.0",
     "winston": "^3.2.1"

plugins/inventory-backend/src/inventory/AggregatorInventory.ts

@@ -14,19 +14,29 @@
  * limitations under the License.
  */
 
+import { NotFoundError } from '@backstage/backend-common';
 import { Component, Inventory } from './types';
 
 export class AggregatorInventory implements Inventory {
   inventories: Inventory[] = [];
 
-  list(): Promise<Component[]> {
-    return Promise.all(this.inventories.map((i) => i.list())).then((lists) =>
-      lists.flat(),
-    );
+  async list(): Promise<Component[]> {
+    const lists = await Promise.all(this.inventories.map((i) => i.list()));
+    return lists.flat();
   }
 
-  item(id: string): Promise<Component | undefined> {
-    return this.list().then((items) => items.find((i) => i.id === id));
+  item(id: string): Promise<Component> {
+    return new Promise((resolve, reject) => {
+      const promises = this.inventories.map((i) =>
+        i.item(id).then(resolve, () => {
+          // For now, just swallow errors in individual inventories;
+          // should handle partial errors better
+        }),
+      );
+      Promise.all(promises).then(() =>
+        reject(new NotFoundError(`Found no component with ID ${id}`)),
+      );
+    });
   }
 
   enlist(inventory: Inventory) {

plugins/inventory-backend/src/inventory/StaticInventory.ts

@@ -14,16 +14,21 @@
  * limitations under the License.
  */
 
+import { NotFoundError } from '@backstage/backend-common';
 import { Component, Inventory } from './types';
 
 export class StaticInventory implements Inventory {
   constructor(private components: Component[]) {}
 
-  list(): Promise<Component[]> {
-    return Promise.resolve([...this.components]);
+  async list(): Promise<Component[]> {
+    return this.components.slice();
   }
 
-  item(id: string): Promise<Component | undefined> {
-    return this.list().then((items) => items.find((i) => i.id === id));
+  async item(id: string): Promise<Component> {
+    const item = this.components.find((i) => i.id === id);
+    if (!item) {
+      throw new NotFoundError(`Found no component with ID ${id}`);
+    }
+    return item;
   }
 }

plugins/inventory-backend/src/inventory/types.ts

@@ -19,6 +19,6 @@ export type Component = {
 };
 
 export type Inventory = {
-  list: () => Promise<Component[]>;
-  item: (id: string) => Promise<Component | undefined>;
+  list(): Promise<Component[]>;
+  item(id: string): Promise<Component>;
 };

plugins/inventory-backend/src/service/router.ts

@@ -16,6 +16,7 @@
 
 import express from 'express';
 import { Logger } from 'winston';
+import Router from 'express-promise-router';
 import { Inventory } from '../inventory';
 
 export interface RouterOptions {
@@ -29,7 +30,7 @@ export async function createRouter(
   const inventory = options.inventory;
   const logger = options.logger.child({ plugin: 'inventory' });
 
-  const router = express.Router();
+  const router = Router();
   router
     .get('/', async (req, res) => {
       const components = await inventory.list();
@@ -38,11 +39,7 @@ export async function createRouter(
     .get('/:id', async (req, res) => {
       const { id } = req.params;
       const component = await inventory.item(id);
-      if (component) {
-        res.status(200).send(component);
-      } else {
-        res.status(404).send();
-      }
+      res.status(200).send(component);
     });
 
   const app = express();