From f25357273165e618e94a1ffb89396f4dd3be4533 Mon Sep 17 00:00:00 2001 From: Dominik Henneke Date: Mon, 19 Jul 2021 14:58:04 +0200 Subject: [PATCH] Implement the etag functionality in the `readUrl` method of `FetchUrlReader` Signed-off-by: Dominik Henneke --- .changeset/friendly-tips-jam.md | 5 ++ .../src/reading/FetchUrlReader.test.ts | 88 +++++++++++++++++++ .../src/reading/FetchUrlReader.ts | 34 ++++--- 3 files changed, 115 insertions(+), 12 deletions(-) create mode 100644 .changeset/friendly-tips-jam.md diff --git a/.changeset/friendly-tips-jam.md b/.changeset/friendly-tips-jam.md new file mode 100644 index 0000000000..806b632ba1 --- /dev/null +++ b/.changeset/friendly-tips-jam.md @@ -0,0 +1,5 @@ +--- +'@backstage/backend-common': patch +--- + +Implement the etag functionality in the `readUrl` method of `FetchUrlReader`. diff --git a/packages/backend-common/src/reading/FetchUrlReader.test.ts b/packages/backend-common/src/reading/FetchUrlReader.test.ts index 169cbfbf66..e8c16c5f0a 100644 --- a/packages/backend-common/src/reading/FetchUrlReader.test.ts +++ b/packages/backend-common/src/reading/FetchUrlReader.test.ts @@ -15,12 +15,16 @@ */ import { ConfigReader } from '@backstage/config'; +import { NotFoundError, NotModifiedError } from '@backstage/errors'; import { msw } from '@backstage/test-utils'; +import { rest } from 'msw'; import { setupServer } from 'msw/node'; import { getVoidLogger } from '../logging'; import { FetchUrlReader } from './FetchUrlReader'; import { DefaultReadTreeResponseFactory } from './tree'; +const fetchUrlReader = new FetchUrlReader(); + describe('FetchUrlReader', () => { const worker = setupServer(); @@ -30,6 +34,39 @@ describe('FetchUrlReader', () => { jest.clearAllMocks(); }); + beforeEach(() => { + worker.use( + rest.get('https://backstage.io/some-resource', (req, res, ctx) => { + if (req.headers.get('if-none-match') === 'foo') { + return res( + ctx.status(304), + ctx.set('Content-Type', 'text/plain'), + ctx.set('etag', 'foo'), + ); + } + + return res( + ctx.status(200), + ctx.set('Content-Type', 'text/plain'), + ctx.set('etag', 'foo'), + ctx.body('content foo'), + ); + }), + ); + + worker.use( + rest.get('https://backstage.io/not-exists', (_req, res, ctx) => { + return res(ctx.status(404)); + }), + ); + + worker.use( + rest.get('https://backstage.io/error', (_req, res, ctx) => { + return res(ctx.status(500), ctx.body('An internal error occured')); + }), + ); + }); + it('factory should create a single entry with a predicate that matches config', async () => { const entries = FetchUrlReader.factory({ config: new ConfigReader({ @@ -70,4 +107,55 @@ describe('FetchUrlReader', () => { expect(predicate(new URL('https://a.examples.org:700/test'))).toBe(true); expect(predicate(new URL('https://a.b.examples.org:700/test'))).toBe(true); }); + + describe('read', () => { + it('should return etag from the response', async () => { + const buffer = await fetchUrlReader.read( + 'https://backstage.io/some-resource', + ); + expect(buffer.toString()).toBe('content foo'); + }); + + it('should throw NotFound if server responds with 404', async () => { + await expect( + fetchUrlReader.read('https://backstage.io/not-exists'), + ).rejects.toThrow(NotFoundError); + }); + + it('should throw Error if server responds with 500', async () => { + await expect( + fetchUrlReader.read('https://backstage.io/error'), + ).rejects.toThrow(Error); + }); + }); + + describe('readUrl', () => { + it('should throw NotModified if server responds with 304', async () => { + await expect( + fetchUrlReader.readUrl('https://backstage.io/some-resource', { + etag: 'foo', + }), + ).rejects.toThrow(NotModifiedError); + }); + + it('should return etag from the response', async () => { + const response = await fetchUrlReader.readUrl( + 'https://backstage.io/some-resource', + ); + expect(response.etag).toBe('foo'); + expect((await response.buffer()).toString()).toEqual('content foo'); + }); + + it('should throw NotFound if server responds with 404', async () => { + await expect( + fetchUrlReader.readUrl('https://backstage.io/not-exists'), + ).rejects.toThrow(NotFoundError); + }); + + it('should throw Error if server responds with 500', async () => { + await expect( + fetchUrlReader.readUrl('https://backstage.io/error'), + ).rejects.toThrow(Error); + }); + }); }); diff --git a/packages/backend-common/src/reading/FetchUrlReader.ts b/packages/backend-common/src/reading/FetchUrlReader.ts index 30468158aa..3177ee1f8e 100644 --- a/packages/backend-common/src/reading/FetchUrlReader.ts +++ b/packages/backend-common/src/reading/FetchUrlReader.ts @@ -14,8 +14,8 @@ * limitations under the License. */ +import { NotFoundError, NotModifiedError } from '@backstage/errors'; import fetch from 'cross-fetch'; -import { NotFoundError } from '@backstage/errors'; import { ReaderFactory, ReadTreeResponse, @@ -57,15 +57,34 @@ export class FetchUrlReader implements UrlReader { }; async read(url: string): Promise { + const response = await this.readUrl(url); + return response.buffer(); + } + + async readUrl( + url: string, + options?: ReadUrlOptions, + ): Promise { let response: Response; try { - response = await fetch(url); + response = await fetch(url, { + headers: { + ...(options?.etag && { 'If-None-Match': options.etag }), + }, + }); } catch (e) { throw new Error(`Unable to read ${url}, ${e}`); } + if (response.status === 304) { + throw new NotModifiedError(); + } + if (response.ok) { - return Buffer.from(await response.text()); + return { + buffer: async () => Buffer.from(await response.text()), + etag: response.headers.get('ETag') ?? undefined, + }; } const message = `could not read ${url}, ${response.status} ${response.statusText}`; @@ -75,15 +94,6 @@ export class FetchUrlReader implements UrlReader { throw new Error(message); } - async readUrl( - url: string, - _options?: ReadUrlOptions, - ): Promise { - // TODO etag is not implemented yet. - const buffer = await this.read(url); - return { buffer: async () => buffer }; - } - async readTree(): Promise { throw new Error('FetchUrlReader does not implement readTree'); }