Remove the dependency on Etag headers for reloading config

Signed-off-by: Matto <muhamadto@gmail.com>
2021-10-21 18:20:36 +11:00
parent e51740f9c9
commit ce843364f0
6 changed files with 73 additions and 106 deletions
@@ -44,7 +44,6 @@
    "json-schema-merge-allof": "^0.8.1",
    "json-schema-traverse": "^1.0.0",
    "typescript-json-schema": "^0.50.1",
-    "uuid": "^8.3.2",
    "yaml": "^1.9.2",
    "yup": "^0.32.9",
    "node-fetch": "2.6.5"
@@ -56,8 +55,7 @@
    "@types/node": "^14.14.32",
    "@types/yup": "^0.29.13",
    "mock-fs": "^5.1.0",
-    "fetch-mock-jest": "1.5.1",
-    "fetch-mock": "^9.11.0"
+    "msw": "^0.29.0"
  },
  "files": [
    "dist"
@@ -18,33 +18,47 @@ import { AppConfig } from '@backstage/config';
 import { loadConfig } from './loader';
 import mockFs from 'mock-fs';
 import fs from 'fs-extra';
-import { v4 as uuidv4 } from 'uuid';
-
-const fetchMock = require('fetch-mock').sandbox();
-const nodeFetch = require('node-fetch');
-
-nodeFetch.default = fetchMock;
+import { rest } from 'msw';
+import { setupServer } from 'msw/node';

 describe('loadConfig', () => {
+  const server = setupServer();
+  const initialLoaderHandler = rest.get(
+    `https://some.domain.io/app-config.yaml`,
+    (_req, res, ctx) => {
+      return res(
+        ctx.body(
+          `app:
+                    title: Remote Example App
+                    sessionKey: 'abc123'
+                    escaped: \$\${Escaped}
+                  `,
+        ),
+      );
+    },
+  );
+
+  const reloadHandler = rest.get(
+    `https://some.domain.io/app-config.yaml`,
+    (_req, res, ctx) => {
+      return res(
+        ctx.body(
+          `app:
+                    title: NEW ReMOTe ExaMPLe App
+                    sessionKey: 'abc123'
+                    escaped: \$\${Escaped}
+                  `,
+        ),
+      );
+    },
+  );
+
+  beforeAll(() => server.listen());
+
  beforeEach(() => {
    process.env.MY_SECRET = 'is-secret';
    process.env.SUBSTITUTE_ME = 'substituted';

-    fetchMock.mock(
-      {
-        url: 'https://some.domain.io/app-config.yaml',
-        method: 'GET',
-      },
-      {
-        body: `app:
-          title: Remote Example App
-          sessionKey: 'abc123'
-          escaped: \$\${Escaped}
-        `,
-        headers: { ETag: uuidv4().toString() },
-      },
-    );
-
    mockFs({
      '/root/app-config.yaml': `
        app:
@@ -87,10 +101,12 @@ describe('loadConfig', () => {
  });

  afterEach(() => {
-    fetchMock.restore();
    mockFs.restore();
+    server.resetHandlers();
  });

+  afterAll(() => server.close());
+
  it('load config from default path', async () => {
    await expect(
      loadConfig({
@@ -113,6 +129,8 @@ describe('loadConfig', () => {
  });

  it('load config from remote path', async () => {
+    server.use(initialLoaderHandler);
+
    const configUrl = 'https://some.domain.io/app-config.yaml';

    await expect(
@@ -267,6 +285,8 @@ describe('loadConfig', () => {
  });

  it('watches remote config urls', async () => {
+    server.use(initialLoaderHandler);
+
    const onChange = defer<AppConfig[]>();
    const stopSignal = defer<void>();

@@ -296,20 +316,7 @@ describe('loadConfig', () => {
      },
    ]);

-    fetchMock.mock(
-      {
-        url: 'https://some.domain.io/app-config.yaml',
-      },
-      {
-        body: `app:
-          title: NEW ReMOTe ExaMPLe App
-          sessionKey: 'abc123'
-          escaped: \$\${Escaped}
-        `,
-        headers: { ETag: uuidv4().toString() },
-      },
-      { overwriteRoutes: true },
-    );
+    server.use(reloadHandler);

    await expect(onChange.promise).resolves.toEqual([
      {
@@ -56,6 +56,7 @@ export type Remote = {
  reloadIntervalSeconds: number;
 };

+/** @public */
 export type RemoteConfigProp = {
  /**
   * URL of the remote config
@@ -111,8 +112,6 @@ export type LoadConfigOptions = {
  watch?: Watch;
 };

-const HTTP_RESPONSE_HEADER_ETAG = 'ETag';
-
 /**
 * Load configuration data.
 *
@@ -128,18 +127,15 @@ export async function loadConfig(
    .filter((e): e is { path: string } => e.hasOwnProperty('path'))
    .map(configTarget => configTarget.path);

-  let configUrls: string[] = options.configTargets
+  const configUrls: string[] = options.configTargets
    .slice()
    .filter((e): e is { url: string } => e.hasOwnProperty('url'))
    .map(configTarget => configTarget.url);

-  const remoteConfigProps: RemoteConfigProp[] = [];
-
  if (remote === undefined && configUrls.length > 0) {
-    console.warn(
+    throw new Error(
      `Remote config detected, however, this feature is turned off. Remote config will be ignored.`,
    );
-    configUrls = [];
  }

  // If no paths are provided, we default to reading
@@ -183,47 +179,32 @@ export async function loadConfig(
  const loadRemoteConfigFiles = async () => {
    const configs: AppConfig[] = [];

-    const readConfigFromUrl = async (remoteConfigProp: RemoteConfigProp) => {
-      const response = await fetch(remoteConfigProp.url);
+    const readConfigFromUrl = async (url: string) => {
+      const response = await fetch(url);
      if (!response.ok) {
-        throw new Error(
-          `Could not read config file at ${remoteConfigProp.url}`,
-        );
+        throw new Error(`Could not read config file at ${url}`);
      }

-      remoteConfigProp.oldETag = remoteConfigProp.newETag ?? undefined;
-      remoteConfigProp.newETag =
-        response.headers.get(HTTP_RESPONSE_HEADER_ETAG) ?? undefined;
-      remoteConfigProp.content = await response.text();
-
-      return remoteConfigProp;
+      return await response.text();
    };

    for (let i = 0; i < configUrls.length; i++) {
-      const remoteConfigProp = await readConfigFromUrl({
-        url: configUrls[i],
-        content: null,
-      });
-
-      if (!isValidUrl(remoteConfigProp.url)) {
-        throw new Error(
-          `Config load path is not valid: '${remoteConfigProp.url}'`,
-        );
+      const configUrl = configUrls[i];
+      if (!isValidUrl(configUrl)) {
+        throw new Error(`Config load path is not valid: '${configUrl}'`);
      }

-      const dir = configRoot;
-      if (!remoteConfigProp.content) {
+      const remoteConfigContent = await readConfigFromUrl(configUrl);
+      if (!remoteConfigContent) {
        throw new Error(`Config is not valid`);
      }
-      const input = yaml.parse(remoteConfigProp.content);
+      const configYaml = yaml.parse(remoteConfigContent);
      const substitutionTransform = createSubstitutionTransform(env);
-      const data = await applyConfigTransforms(dir, input, [
+      const data = await applyConfigTransforms(configRoot, configYaml, [
        substitutionTransform,
      ]);

-      configs.push({ data, context: remoteConfigProp.url });
-
-      remoteConfigProps.push(remoteConfigProp);
+      configs.push({ data, context: configUrl });
    }

    return configs;
@@ -277,17 +258,12 @@ export async function loadConfig(
  };

  const watchRemoteConfig = (watchProp: Watch, remoteProp: Remote) => {
-    const hasConfigChanged = async (remoteConfigProp: RemoteConfigProp) => {
-      const requestProps = { method: 'HEAD' };
-      const { headers } = await fetch(remoteConfigProp.url, requestProps);
-      remoteConfigProp.oldETag = remoteConfigProp.newETag ?? undefined;
-      remoteConfigProp.newETag =
-        headers.get(HTTP_RESPONSE_HEADER_ETAG) ?? undefined;
-
+    const hasConfigChanged = async (
+      oldRemoteConfigs: AppConfig[],
+      newRemoteConfigs: AppConfig[],
+    ) => {
      return (
-        remoteConfigProp.oldETag !== undefined &&
-        remoteConfigProp.newETag !== undefined &&
-        remoteConfigProp.oldETag !== remoteConfigProp.newETag
+        JSON.stringify(oldRemoteConfigs) !== JSON.stringify(newRemoteConfigs)
      );
    };

@@ -295,18 +271,12 @@ export async function loadConfig(
    try {
      handle = setInterval(async () => {
        console.info(`Checking for config update`);
-        for (const remoteConfigProp of remoteConfigProps) {
-          if (await hasConfigChanged(remoteConfigProp)) {
-            console.info(`Remote config change, reloading config ...`);
-            const newRemoteConfigs = await loadRemoteConfigFiles();
-            watchProp.onChange([
-              ...newRemoteConfigs,
-              ...fileConfigs,
-              ...envConfigs,
-            ]);
-            console.info(`Remote config reloaded`);
-            break;
-          }
+        const newRemoteConfigs = await loadRemoteConfigFiles();
+        if (await hasConfigChanged(remoteConfigs, newRemoteConfigs)) {
+          remoteConfigs = newRemoteConfigs;
+          console.info(`Remote config change, reloading config ...`);
+          watchProp.onChange([...remoteConfigs, ...fileConfigs, ...envConfigs]);
+          console.info(`Remote config reloaded`);
        }
      }, remoteProp.reloadIntervalSeconds * 1000);
    } catch (error) {