Initial commit

.babelrc

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+{
+  "presets": ["es2015-node5"]
+}

.dockerignore

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+.git
+.gitignore
+.envrc
+.babelrc
+.eslintrc
+dev.js
+npm-debug.log
+
+src/
+node_modules/

.eslintrc

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+{
+  "parser": "babel-eslint",
+  "extends": "airbnb/base"
+}

.fonts.conf

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+<?xml version='1.0'?>
+<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
+<fontconfig>
+ <match target="font">
+  <edit mode="assign" name="rgba">
+   <const>rgb</const>
+  </edit>
+ </match>
+ <match target="font">
+  <edit mode="assign" name="hinting">
+   <bool>true</bool>
+  </edit>
+ </match>
+ <match target="font">
+  <edit mode="assign" name="hintstyle">
+   <const>hintslight</const>
+  </edit>
+ </match>
+ <match target="font">
+  <edit mode="assign" name="antialias">
+   <bool>true</bool>
+  </edit>
+ </match>
+  <match target="font">
+    <edit mode="assign" name="lcdfilter">
+      <const>lcddefault</const>
+    </edit>
+  </match>
+</fontconfig>

.gitignore

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+lib/
+node_modules/
+.envrc
+npm-debug.log

Dockerfile

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+FROM node:slim
+
+ENV RENDERER_ACCESS_KEY=changeme CONCURRENCY=1
+
+# Add subpixel hinting
+COPY .fonts.conf /root
+
+COPY . /app
+WORKDIR /app
+
+# Install the packages needed to run Electron
+RUN npm install --production && \
+    sed -i 's/main/main contrib/g' /etc/apt/sources.list && \
+    apt-get update && apt-get install -y xvfb \
+      libgtk2.0-0 ttf-mscorefonts-installer libnotify4 libgconf2-4 libnss3 && \
+    apt-get clean
+
+EXPOSE 3000
+CMD xvfb-run --server-args="-screen 0 800x600x24" npm start

LICENSE.md

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+The MIT License (MIT)
+
+Copyright (c) 2016 Mihkel Sokk <[email protected]>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# electron-render-service
+[![Docker Hub](https://img.shields.io/badge/docker-ready-blue.svg)](https://registry.hub.docker.com/u/msokk/electron-render-service/)
+[![](https://badge.imagelayers.io/msokk/electron-render-service:latest.svg)](https://imagelayers.io/?images=msokk/electron-render-service:latest 'Get your own badge on imagelayers.io')
+
+Simple PDF render service, accepts webpage URL and returns it as a PDF.
+
+
+## Docker usage
+
+Based on official [Node.js Jessie](https://hub.docker.com/_/node/) image,
+uses latest [electron](https://github.com/atom/electron).
+
+
+1. `docker run -t -e RENDERER_ACCESS_KEY=secret -p 3000:3000 msokk/electron-render-service`
+2. `wget -o out.pdf http://<node_address>:3000/pdf?url=https://github.com/msokk/electron-render-service&access_key=secret`
+
+
+## Installation on Debian with Node.js
+
+```sh
+# Enable contrib packages
+sed -i 's/main/main contrib/g' /etc/apt/sources.list
+
+# Install packages needed for runtime
+apt-get update && apt-get install -y xvfb libgtk2.0-0 ttf-mscorefonts-installer libnotify4 libgconf2-4 libnss3
+
+# Clone project (not yet on NPM)
+git clone https://github.com/msokk/electron-render-service.git
+npm install
+
+# Run in virtual framebuffer
+RENDERER_ACCESS_KEY=secret xvfb-run --server-args="-screen 0 800x600x24" npm start
+
+wget -o out.pdf http://localhost:3000/pdf?url=https://github.com/msokk/electron-render-service&access_key=secret
+```
+
+## Endpoints
+
+#### `GET /pdf` - Render PDF
+
+> Query params ([About PDF params](https://github.com/atom/electron/blob/master/docs/api/web-contents.md#webcontentsprinttopdfoptions-callback)):
+
+  * `access_key` - Authentication key.
+  * `url` - Full URL to fetch.
+  * `pageSize` - Specify page size of the generated PDF. (default: `A4`)
+  * `marginsType` - Specify the type of margins to use (default: `0`)
+  * `printBackground` - Whether to print CSS backgrounds. (default: `true`)
+  * `landscape` -  `true` for landscape, `false` for portrait. (default: `false`)
+
+
+#### `GET /stats` - Display render pool stats
+
+> Query params:
+
+* `access_key` - Generic authentication key is required.
+
+
+## Environment variables
+
+##### *Required*
+* `RENDERER_ACCESS_KEY` or `RENDERER_ACCESS_KEY_<suffix>` - Secret key for limiting access. Suffixed keys are used as labels in access log for debugging usage.
+
+##### *Optional*
+* `CONCURRENCY` - Number of browser windows to run in parallel (default: `1`)
+* `INTERFACE` - Network interface for Express to listen on (default: `0.0.0.0`)
+* `PORT` - (default: `3000`)

dev.js

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+require('babel-register');
+require('./src/server');

package.json

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+{
+  "name": "electron-render-service",
+  "version": "0.1.0",
+  "description": "Microservice for rendering PDFs from HTML with Electron",
+  "scripts": {
+    "start": "electron lib/server.js",
+    "dev": "electron dev.js",
+    "build": "babel src -d lib"
+  },
+  "keywords": [
+    "electron",
+    "render",
+    "pdf",
+    "html",
+    "microservice"
+  ],
+  "author": "Mihkel Sokk <[email protected]>",
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/msokk/electron-render-service.git"
+  },
+  "dependencies": {
+    "async": "^1.5.2",
+    "electron-prebuilt": "^0.36.4",
+    "express": "^4.13.3",
+    "morgan": "^1.6.1"
+  },
+  "devDependencies": {
+    "babel-cli": "^6.4.0",
+    "babel-eslint": "5.0.0-beta6",
+    "babel-preset-es2015-node5": "^1.1.1",
+    "babel-register": "^6.4.3",
+    "eslint": "^1.10.3",
+    "eslint-config-airbnb": "^3.1.0"
+  }
+}

src/auth.js

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+const KEY_PREFIX = 'RENDERER_ACCESS_KEY';
+const validKeys = {};
+
+// Global key
+if (process.env[KEY_PREFIX]) validKeys.global = process.env[KEY_PREFIX];
+
+// Labeled keys
+Object.keys(process.env)
+  .filter(k => k.startsWith(KEY_PREFIX + '_'))
+  .filter(k => process.env[k].length > 0)
+  .forEach(k => validKeys[k.replace(KEY_PREFIX + '_', '').toLowerCase()] = process.env[k]);
+
+if (Object.keys(validKeys).length === 0) throw new Error('No access key defined!');
+
+/**
+ * Simple token auth middleware
+ */
+export default function authMiddleware(req, res, next) {
+  const sentKey = req.query.access_key;
+  const key = Object.keys(validKeys).filter(k => validKeys[k] === sentKey);
+  if (!sentKey || key.length === 0) return res.sendStatus(403);
+
+  req.keyLabel = key[0];
+  next();
+}

src/render_pool.js

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+import pjson from '../package.json';
+import { queue } from 'async';
+import { BrowserWindow } from 'electron';
+
+const DEFAULT_HEADERS = 'Cache-Control: no-cache, no-store, must-revalidate';
+const CONCURRENCY = process.env.CONCURRENCY || 1;
+const windowPool = [];
+
+/**
+ * Get renderer from pool and lock it
+ */
+function getRenderer() {
+  const win = windowPool.filter(p => p.busy === false)[0];
+  if (win) windowPool[win.id - 1].busy = true;
+  return win;
+}
+
+
+// Render queue
+const rendererQueue = queue(({ type, res, url, options }, done) => {
+  const win = getRenderer();
+  if (!win) throw new Error('Pool is empty?');
+
+  const { webContents } = win;
+  webContents.loadURL(url, { extraHeaders: DEFAULT_HEADERS });
+
+  webContents.once('did-finish-load', () => {
+    if (type === 'pdf') {
+      webContents.printToPDF(options, (error, data) => {
+        if (error) throw error;
+
+        res.set('Content-Disposition', `inline; filename="render-${Date.now()}.pdf"`);
+        res.type('pdf').send(data);
+        win.release();
+        done();
+      });
+    }
+  });
+}, CONCURRENCY);
+
+
+export default {
+  /**
+   * Push a render task to queue
+   */
+  enqueue(task) {
+    rendererQueue.push(task);
+  },
+
+  /**
+   * Fetch stats for debugging
+   */
+  stats() {
+    return {
+      concurrency: rendererQueue.concurrency,
+      length: rendererQueue.length(),
+      workersList: rendererQueue.workersList().map(({ data }) =>
+        ({ url: data.url, options: data.options, type: data.type })),
+    };
+  },
+
+  /**
+   * Create Electron window pool
+   */
+  init() {
+    Array.from({ length: CONCURRENCY }, (v, k) => k).forEach(i => {
+      const browserWindow = new BrowserWindow({ show: false });
+
+      // Set user agent
+      const webContents = browserWindow.webContents;
+      webContents.setUserAgent(`${webContents.getUserAgent()} ${pjson.name}/${pjson.version}`);
+
+      // Basic locking
+      browserWindow.busy = false;
+      browserWindow.release = () => windowPool[i].busy = false;
+
+      // Add to pool
+      windowPool.push(browserWindow);
+    });
+  },
+};

src/server.js

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+import express from 'express';
+import morgan from 'morgan';
+import { app as electronApp } from 'electron';
+
+import renderPool from './render_pool';
+import auth from './auth';
+
+const INTERFACE = process.env.INTERFACE || '0.0.0.0';
+const PORT = process.env.PORT || 3000;
+const app = express();
+
+function printPDFUsage(url = '') {
+  return `Usage: GET ${url}/pdf?url=http://google.com&access_key=<token>`;
+}
+
+// Log with token
+morgan.token('key-label', req => req.keyLabel);
+app.use(morgan(`[:date[iso]] :key-label@:remote-addr - :method :status
+:url :res[content-length] ":user-agent" :response-time ms`.replace('\n', '')));
+
+
+/**
+ * GET /pdf - Render PDF
+ *
+ * Query: https://github.com/atom/electron/blob/master/docs/api/web-contents.md#webcontentsprinttopdfoptions-callback
+ */
+app.get('/pdf', auth, (req, res) => {
+  const { url = 'data:text/plain;charset=utf-8,' + printPDFUsage(),
+    marginsType = 0, pageSize = 'A4', printBackground = true, landscape = false } = req.query;
+
+  renderPool.enqueue({ url, res, type: 'pdf',
+    options: { marginsType, pageSize, landscape, printBackground } });
+});
+
+
+/**
+ * GET /stats - Output some stats as JSON
+ */
+app.get('/stats', auth, (req, res) => {
+  if (req.keyLabel !== 'global') return res.sendStatus(403);
+
+  res.send(renderPool.stats());
+});
+
+
+/**
+ * GET / - Print usage
+ */
+app.get('/', (req, res) => res.status(404).send(printPDFUsage()));
+
+
+// Electron finished booting
+electronApp.on('ready', () => {
+  renderPool.init();
+
+  const listener = app.listen(PORT, INTERFACE, () => {
+    const { port, address } = listener.address();
+    const url = `http://${address}:${port}`;
+    process.stdout.write(`Renderer listening on ${url}\n\n`);
+    process.stdout.write(printPDFUsage(url) + '\n');
+  });
+});
+
+
+// Stop Electron on SIG*
+process.on('exit', code => electronApp.exit(code));