Add redirector worker

.editorconfig

@@ -0,0 +1,26 @@
+# EditorConfig is awesome: http://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space
+
+[*.js]
+indent_size = 4
+
+[*.json]
+indent_size = 4
+
+[*.css]
+indent_size = 4
+
+[*.html]
+indent_size = 2
+
+[package.json]
+indent_size = 2

.eslintrc.js

@@ -0,0 +1,19 @@
+module.exports = {
+    "env": {
+        "browser": false,
+        "commonjs": true,
+        "es6": true,
+        "mocha": true,
+        "worker": true
+    },
+    "extends": "eslint:recommended",
+    "globals": {
+        "Atomics": "readonly",
+        "SharedArrayBuffer": "readonly"
+    },
+    "parserOptions": {
+        "ecmaVersion": 2018
+    },
+    "rules": {
+    }
+};

.travis.yml

@@ -0,0 +1,4 @@
+language: node_js
+node_js:
+  - "10"
+cache: yarn

README.md

@@ -1,2 +1,19 @@
 # www-workers
+
 Cloudflare Workers for www.mozilla.org
+
+## Install
+
+First make sure you have [Node](https://nodejs.org/) and [Yarn](https://yarnpkg.com/) installed. Then run:
+
+```
+yarn
+```
+
+## Test
+
+To run unit tests:
+
+```
+npm test
+```

package.json

@@ -0,0 +1,26 @@
+{
+  "name": "www-workers",
+  "private": true,
+  "version": "1.0.0",
+  "description": "Cloudflare Workers for www.mozilla.org",
+  "scripts": {
+    "pretest": "./node_modules/.bin/eslint .",
+    "test": "mocha --timeout 20000"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/mozmeao/www-workers.git"
+  },
+  "author": "Mozilla",
+  "license": "MPL-2.0",
+  "bugs": {
+    "url": "https://github.com/mozmeao/www-workers/issues"
+  },
+  "devDependencies": {
+    "@dollarshaveclub/cloudworker": "^0.1.1",
+    "chai": "^4.2.0",
+    "eslint": "^6.5.1",
+    "mocha": "^6.2.1",
+    "sinon": "^7.5.0"
+  }
+}

test/redirector-test.js

@@ -0,0 +1,53 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const expect = require('chai').expect;
+const sinon = require('sinon');
+
+
+before(async function () {
+    const context = new (require('@dollarshaveclub/cloudworker'))(require('fs').readFileSync('workers/redirector.js', 'utf8')).context;
+    global.Request = context.Request
+    global.URL = context.URL
+    global.handleRequest = context.handleRequest;
+});
+
+describe('Redirector Worker', function() {
+
+    it('should return a 200 for requests that have a matching response, but are not within sample rate', async function () {
+        Math.random = sinon.stub().returns(0.8534);
+        const url = new URL('https://bedrock-stage.gcp.moz.works/en-US/firefox/new/');
+        const req = new Request(url);
+        const res = await global.handleRequest(req);
+        expect(res.status).to.equal(200);
+        expect(res.url).to.equal('https://bedrock-stage.gcp.moz.works/en-US/firefox/new/');
+    });
+
+    it('should return a 302 for requests that have a matching response, and are within sample rate', async function () {
+        Math.random = sinon.stub().returns(0.0001);
+        const url = new URL('https://bedrock-stage.gcp.moz.works/en-US/firefox/new/');
+        const req = new Request(url);
+        const res = await global.handleRequest(req);
+        expect(res.status).to.equal(302);
+        expect(res.headers.get('location')).to.equal('https://bedrock-stage.gcp.moz.works/en-US/exp/firefox/new/');
+    });
+
+    it('should preserve query string parameters when redirecting the URL', async function() {
+        Math.random = sinon.stub().returns(0.0001);
+        const url = new URL('https://bedrock-stage.gcp.moz.works/en-US/firefox/new/?foo=bar');
+        const req = new Request(url);
+        const res = await global.handleRequest(req);
+        expect(res.status).to.equal(302);
+        expect(res.headers.get('location')).to.equal('https://bedrock-stage.gcp.moz.works/en-US/exp/firefox/new/?foo=bar');
+    });
+
+    it('should return a 200 if the request does not have a matching redirect', async function() {
+        const url = new URL('https://bedrock-stage.gcp.moz.works/en-US/firefox/');
+        const req = new Request(url);
+        const res = await global.handleRequest(req);
+        expect(res.status).to.equal(200);
+        expect(res.url).to.equal('https://bedrock-stage.gcp.moz.works/en-US/firefox/');
+    });
+});
+

workers/redirector.js

@@ -0,0 +1,60 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This is a custom URL redirector implemented as a CloudFlare Worker.
+ * The role of the worker is to redirect a predefined % of traffic
+ * to a different URL (used for A/B testing).
+ * API documentation can be found at https://developers.cloudflare.com/workers/
+ */
+
+/**
+ * `targetPath` is the target pathname that the worker looks to match against.
+ * `sandboxPath` is the sandbox experiment pathname to redirect to.
+ * `sampleRate` is the proporation of traffic that should be redirected (a value of 0.1 equates to 10%).
+ */
+const experimentPages = [
+    {
+        'targetPath': `/en-US/firefox/new/`,
+        'sandboxPath': `/en-US/exp/firefox/new/`,
+        'sampleRate': 0.06
+    }
+];
+
+function isWithinSampleRate(SAMPLE_RATE) {
+    return Math.random() < SAMPLE_RATE;
+}
+
+async function handleRequest(request) {
+    // Get the current request URL.
+    const requestURL = new URL(request.url);
+
+    // Split out search params from the origin and pathname.
+    const origin = requestURL.origin;
+    const pathname = requestURL.pathname;
+    const search = requestURL.search;
+
+    // Check to see if the URL matches a route.
+    const match = experimentPages.filter(page => pathname === page.targetPath);
+
+    if (match.length > 0) {
+        // Assume only the first match found will be processed.
+        const sandbox = match[0];
+
+        // Get the experimental URL to redirect to.
+        const experimentURL = search ? `${origin}${sandbox.sandboxPath}${search}` : `${origin}${sandbox.sandboxPath}`;
+
+        // Only redirect a pre-defined % of requests per-page.
+        if (experimentURL && isWithinSampleRate(sandbox.sampleRate)) {
+            return Response.redirect(experimentURL, 302);
+        }
+    }
+
+    // Fetch the original request if no redirect was fulfilled.
+    return await fetch(request);
+}
+
+addEventListener('fetch', event => {
+    event.respondWith(handleRequest(event.request))
+});