Expose experiments and feature flags on /__frontend_version__ (#6340)

package.json

@@ -215,6 +215,7 @@
     "extract-text-webpack-plugin": "3.0.2",
     "fastclick": "1.0.6",
     "focus-visible": "4.1.5",
+    "fs-extra": "7.0.0",
     "full-icu": "1.2.1",
     "helmet": "3.13.0",
     "history": "4.7.2",

src/core/server/base.js

@@ -24,6 +24,7 @@ import * as middleware from 'core/middleware';
 import { loadErrorPage } from 'core/reducers/errorPage';
 import { dismissSurvey } from 'core/reducers/survey';
 import { addQueryParamsToHistory, convertBoolean } from 'core/utils';
+import { viewFrontendVersionHandler } from 'core/utils/server';
 import {
   setAuthToken,
   setClientApp,
@@ -182,26 +183,11 @@ function baseServer(
     app.use(middleware.serveAssetsLocally());
   }
 
-  // Show version/commit information as JSON.
-  function viewVersion(req, res) {
-    // This is a magic file that gets written by deployment scripts.
-    const version = path.join(config.get('basePath'), 'version.json');
-
-    fs.stat(version, (error) => {
-      if (error) {
-        log.error(`Could not stat version file ${version}: ${error}`);
-        res.sendStatus(415);
-      } else {
-        res.setHeader('Content-Type', 'application/json');
-        fs.createReadStream(version).pipe(res);
-      }
-    });
-  }
-
-  // Following the ops monitoring convention, return version info at this URL.
-  app.get('/__version__', viewVersion);
+  // Following the ops monitoring Dockerflow convention, return version info at
+  // this URL. See: https://github.com/mozilla-services/Dockerflow
+  app.get('/__version__', viewFrontendVersionHandler());
   // For AMO, this helps differentiate from /__version__ served by addons-server.
-  app.get('/__frontend_version__', viewVersion);
+  app.get('/__frontend_version__', viewFrontendVersionHandler());
 
   // Return 200 for csp reports - this will need to be overridden when deployed.
   app.post('/__cspreport__', (req, res) => res.status(200).end('ok'));

src/core/utils/server.js

@@ -0,0 +1,59 @@
+/* @flow */
+import path from 'path';
+
+import fs from 'fs-extra';
+import config from 'config';
+import type { $Request, $Response } from 'express';
+
+import log from 'core/logger';
+
+const PREFIX = 'enableFeature';
+
+type ExpressHandler = (req: $Request, res: $Response) => void;
+
+type ViewFrontendVersionHandlerParams = {|
+  _config?: typeof config,
+  _log?: typeof log,
+  versionFilename?: string,
+|};
+
+export const viewFrontendVersionHandler = ({
+  _config = config,
+  _log = log,
+  // This is a magic file that gets written by deployment scripts.
+  versionFilename = 'version.json',
+}: ViewFrontendVersionHandlerParams = {}): ExpressHandler => {
+  const version = path.join(_config.get('basePath'), versionFilename);
+
+  const featureFlags = Object.keys(_config)
+    .filter((key) => {
+      return key.startsWith(PREFIX);
+    })
+    .reduce((map, key) => {
+      return {
+        ...map,
+        [key]: _config.get(key),
+      };
+    }, {});
+
+  const experiments = _config.get('experiments');
+
+  return (req: $Request, res: $Response) => {
+    fs.stat(version, async (error) => {
+      if (error) {
+        _log.error(
+          `Could not stat version file ${version}: ${error.toString()}`,
+        );
+        res.sendStatus(415);
+      } else {
+        const versionJson = await fs.readJson(version);
+
+        res.json({
+          ...versionJson,
+          experiments,
+          feature_flags: featureFlags,
+        });
+      }
+    });
+  };
+};

tests/unit/core/utils/fixtures/version.json

@@ -0,0 +1,6 @@
+{
+    "build": "https://circleci.com/gh/mozilla/addons-frontend/10080",
+    "commit": "afb29ad060fcdb84e300ebb16aea69cee06d4d5e",
+    "source": "https://github.com/mozilla/addons-frontend",
+    "version": ""
+}

tests/unit/core/utils/test_server.js

@@ -0,0 +1,82 @@
+import path from 'path';
+
+import fs from 'fs-extra';
+import MockExpressResponse from 'mock-express-response';
+
+import { viewFrontendVersionHandler } from 'core/utils/server';
+import { getFakeConfig } from 'tests/unit/helpers';
+
+describe(__filename, () => {
+  describe('viewFrontendVersionHandler', () => {
+    const basePath = path.join(__dirname, 'fixtures');
+    const versionJson = fs.readJsonSync(path.join(basePath, 'version.json'));
+
+    it('exposes the version.json file', (done) => {
+      const _config = getFakeConfig({ basePath });
+      const handler = viewFrontendVersionHandler({ _config });
+
+      const res = new MockExpressResponse();
+      handler(null, res);
+
+      res.on('finish', () => {
+        expect(res.statusCode).toEqual(200);
+        expect(res.get('content-type')).toEqual(
+          'application/json; charset=utf-8',
+        );
+        expect(res._getJSON()).toMatchObject(versionJson);
+
+        done();
+      });
+    });
+
+    it('exposes the experiments and feature flags', (done) => {
+      const experiments = {
+        ab_test_1: true,
+      };
+      const featureFlags = {
+        enableFeatureFoo001: true,
+        enableFeatureBar123: false,
+      };
+
+      const _config = getFakeConfig(
+        { basePath, experiments, ...featureFlags },
+        { allowUnknownKeys: true },
+      );
+      const handler = viewFrontendVersionHandler({ _config });
+
+      const res = new MockExpressResponse();
+      handler(null, res);
+
+      res.on('finish', () => {
+        expect(res._getJSON()).toMatchObject({
+          ...versionJson,
+          experiments,
+          feature_flags: {
+            ...featureFlags,
+          },
+        });
+
+        done();
+      });
+    });
+
+    it('returns a 415 and logs an error when file does not exist', (done) => {
+      const _config = getFakeConfig({ basePath: '/some/invalid/path' });
+      const _log = {
+        error: sinon.stub(),
+      };
+
+      const handler = viewFrontendVersionHandler({ _config, _log });
+
+      const res = new MockExpressResponse();
+      handler(null, res);
+
+      res.on('finish', () => {
+        expect(res.statusCode).toEqual(415);
+        sinon.assert.calledOnce(_log.error);
+
+        done();
+      });
+    });
+  });
+});

tests/unit/helpers.js

@@ -442,9 +442,12 @@ export function createFakeUserAbuseReport({
 // if (fakeConfig.get('isDevelopment')) {
 //   ...
 // }
-export const getFakeConfig = (params = {}) => {
+export const getFakeConfig = (
+  params = {},
+  { allowUnknownKeys = false } = {},
+) => {
   for (const key of Object.keys(params)) {
-    if (!config.has(key)) {
+    if (!config.has(key) && !allowUnknownKeys) {
       // This will help alert us when a test accidentally relies
       // on an invalid config key.
       throw new Error(

tests/unit/test_helpers.js

@@ -11,6 +11,7 @@ import { put, takeLatest } from 'redux-saga/effects';
 /* eslint-enable import/order */
 
 import {
+  getFakeConfig,
   matchingSagaAction,
   shallowUntilTarget,
   unexpectedSuccess,
@@ -274,4 +275,22 @@ describe(__filename, () => {
       );
     });
   });
+
+  describe('getFakeConfig', () => {
+    it('throws an error when key is invalid', () => {
+      expect(() => {
+        getFakeConfig({ thisIsAnInvalidKey: true });
+      }).toThrow(/this key is invalid/);
+    });
+
+    it('does not throw when key is invalid and allowUnknownKeys is set to true', () => {
+      const value = 'some value';
+      const config = getFakeConfig(
+        { thisIsAnInvalidKey: value },
+        { allowUnknownKeys: true },
+      );
+
+      expect(config.get('thisIsAnInvalidKey')).toEqual(value);
+    });
+  });
 });

version.json

@@ -0,0 +1,6 @@
+{
+    "build": "https://circleci.com/gh/mozilla/addons-frontend/10080",
+    "commit": "afb29ad060fcdb84e300ebb16aea69cee06d4d5e",
+    "source": "https://github.com/mozilla/addons-frontend",
+    "version": ""
+}

yarn.lock

@@ -4840,6 +4840,14 @@ fs-copy-file-sync@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/fs-copy-file-sync/-/fs-copy-file-sync-1.1.1.tgz#11bf32c096c10d126e5f6b36d06eece776062918"
 
+fs-extra@7.0.0:
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-7.0.0.tgz#8cc3f47ce07ef7b3593a11b9fb245f7e34c041d6"
+  dependencies:
+    graceful-fs "^4.1.2"
+    jsonfile "^4.0.0"
+    universalify "^0.1.0"
+
 fs-extra@^0.30.0:
   version "0.30.0"
   resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-0.30.0.tgz#f233ffcc08d4da7d432daa449776989db1df93f0"
@@ -6909,6 +6917,12 @@ jsonfile@^2.1.0:
   optionalDependencies:
     graceful-fs "^4.1.6"
 
+jsonfile@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-4.0.0.tgz#8771aae0799b64076b76640fca058f9c10e33ecb"
+  optionalDependencies:
+    graceful-fs "^4.1.6"
+
 jsonify@~0.0.0:
   version "0.0.0"
   resolved "https://registry.yarnpkg.com/jsonify/-/jsonify-0.0.0.tgz#2c74b6ee41d93ca51b7b5aaee8f503631d252a73"
@@ -12099,6 +12113,10 @@ unist-util-visit@^1.1.0:
   dependencies:
     unist-util-is "^2.1.1"
 
+universalify@^0.1.0:
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/universalify/-/universalify-0.1.2.tgz#b646f69be3942dabcecc9d6639c80dc105efaa66"
+
 unpipe@1.0.0, unpipe@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/unpipe/-/unpipe-1.0.0.tgz#b2bf4ee8514aae6165b4817829d21b2ef49904ec"