Add puppeteer sample (Headless Chrome) (#625)

Author: steren

appengine/headless-chrome/README.md

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+# Headless Chrome on Google App Engine
+
+This sample application demonstrates how to use Headless Chrome via the [Puppeteer](https://developers.google.com/web/tools/puppeteer/) module to take screenshots of webpages on [Google App Engine](https://cloud.google.com/appengine) Node.js [standard environment](https://cloud.google.com/appengine/docs/standard/nodejs).
+
+## Running and deploying
+
+Refer to the [appengine/README.md](../README.md) file for instructions on running and deploying.

appengine/headless-chrome/app.js

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+/*
+Copyright 2018 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+'use strict';
+
+// [START full_sample]
+const express = require('express');
+const puppeteer = require('puppeteer');
+const app = express();
+
+app.use(async (req, res) => {
+  const url = req.query.url;
+
+  if (!url) {
+    return res.send('Please provide URL as GET parameter, for example: <a href="/?url=https://example.com">?url=https://example.com</a>');
+  }
+
+  // [START browser]
+  const browser = await puppeteer.launch({
+    args: ['--no-sandbox', '--disable-setuid-sandbox']
+  });
+  // [END browser]
+  const page = await browser.newPage();
+  await page.goto(url);
+  const imageBuffer = await page.screenshot();
+  await browser.close();
+
+  res.set('Content-Type', 'image/png');
+  res.send(imageBuffer);
+});
+
+const server = app.listen(process.env.PORT || 8080, err => {
+  if (err) return console.error(err);
+  const port = server.address().port;
+  console.info(`App listening on port ${port}`);
+});
+// [END full_sample]
+
+module.exports = app;

appengine/headless-chrome/app.standard.yaml

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+# Copyright 2018, Google LLC
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License
+
+# [START app_yaml]
+runtime: nodejs8
+instance_class: F4_1G
+# [END app_yaml]

appengine/headless-chrome/package.json

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+{
+  "name": "headless-chrome-sample",
+  "engines": {
+    "node": "8.x"
+  },
+  "version": "1.0.0",
+  "description": "An example of taking screenshot with Puppeteer (Headless Chrome) in Node.js on Google App Engine.",
+  "scripts": {
+    "start": "node app.js",
+    "system-test": "repo-tools test app",
+    "unit-test": "ava --verbose test/*.test.js",
+    "lint": "repo-tools lint",
+    "pretest": "npm run lint",
+    "test": "npm run unit-test && npm run system-test"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git"
+  },
+  "author": {
+    "name": "Google LLC"
+  },
+  "license": "Apache-2.0",
+  "dependencies": {
+    "express": "^4.16.3",
+    "puppeteer": "^1.2.0"
+  },
+  "devDependencies": {
+    "@google-cloud/nodejs-repo-tools": "2.3.0",
+    "ava": "^0.25.0",
+    "semistandard": "^12.0.1"
+  },
+  "cloud-repo-tools": {
+    "test": {
+      "app": {
+        "msg": "Please provide URL"
+      }
+    },
+    "requiresKeyFile": true,
+    "requiresProjectId": true
+  }
+}

appengine/headless-chrome/test/app.test.js

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+// Copyright 2017, Google, Inc.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// NOTE:
+// This app can only be fully tested when deployed, because
+// Pub/Sub requires a live endpoint URL to hit. Nevertheless,
+// these tests mock it and partially test it locally.
+
+'use strict';
+
+const test = require(`ava`);
+const path = require(`path`);
+const utils = require(`@google-cloud/nodejs-repo-tools`);
+
+const cwd = path.join(__dirname, `../`);
+const requestObj = utils.getRequest({ cwd: cwd });
+
+test.serial.cb(`should return a screenshot`, t => {
+  requestObj
+    .get(`/?url=https://example.com`)
+    .send()
+    .expect(200)
+    .expect(response => {
+      t.is(response.type, `image/png`);
+      t.true(response.body instanceof Buffer);
+      t.true(response.body.length > 0);
+    })
+    .end(t.end);
+});