chromium/source/index.ts

import { access, createWriteStream, existsSync, mkdirSync, readdirSync, symlink, unlinkSync } from 'fs';
import { IncomingMessage } from 'http';
import LambdaFS from './lambdafs';
import { join } from 'path';
import { URL } from 'url';

/** Viewport taken from https://github.com/puppeteer/puppeteer/blob/main/docs/api/puppeteer.viewport.md */
interface Viewport {
  /**
   * The page width in pixels.
   */
  width: number;
  /**
   * The page height in pixels.
   */
  height: number;
  /**
   * Specify device scale factor.
   * See {@link https://developer.mozilla.org/en-US/docs/Web/API/Window/devicePixelRatio | devicePixelRatio} for more info.
   * @defaultValue 1
   */
  deviceScaleFactor?: number;
  /**
   * Whether the `meta viewport` tag is taken into account.
   * @defaultValue false
   */
  isMobile?: boolean;
  /**
   * Specifies if the viewport is in landscape mode.
   * @defaultValue false
   */
  isLandscape?: boolean;
  /**
   * Specify if the viewport supports touch events.
   * @defaultValue false
   */
  hasTouch?: boolean;
}

if (/^AWS_Lambda_nodejs(?:10|12|14|16)[.]x$/.test(process.env.AWS_EXECUTION_ENV) === true) {
  if (process.env.FONTCONFIG_PATH === undefined) {
    process.env.FONTCONFIG_PATH = '/tmp/aws';
  }

  if (process.env.LD_LIBRARY_PATH === undefined) {
    process.env.LD_LIBRARY_PATH = '/tmp/aws/lib';
  } else if (process.env.LD_LIBRARY_PATH.startsWith('/tmp/aws/lib') !== true) {
    process.env.LD_LIBRARY_PATH = [...new Set(['/tmp/aws/lib', ...process.env.LD_LIBRARY_PATH.split(':')])].join(':');
  }
}

class Chromium {
  /**
   * Downloads or symlinks a custom font and returns its basename, patching the environment so that Chromium can find it.
   * If not running on AWS Lambda nor Google Cloud Functions, `null` is returned instead.
   */
  static font(input: string): Promise<string> {
    if (Chromium.headless !== true) {
      return null;
    }

    if (process.env.HOME === undefined) {
      process.env.HOME = '/tmp';
    }

    if (existsSync(`${process.env.HOME}/.fonts`) !== true) {
      mkdirSync(`${process.env.HOME}/.fonts`);
    }

    return new Promise((resolve, reject) => {
      if (/^https?:[/][/]/i.test(input) !== true) {
        input = `file://${input}`;
      }

      const url = new URL(input);
      const output = `${process.env.HOME}/.fonts/${url.pathname.split('/').pop()}`;

      if (existsSync(output) === true) {
        return resolve(output.split('/').pop());
      }

      if (url.protocol === 'file:') {
        access(url.pathname, (error) => {
          if (error != null) {
            return reject(error);
          }

          symlink(url.pathname, output, (error) => {
            return error != null ? reject(error) : resolve(url.pathname.split('/').pop());
          });
        });
      } else {
        let handler = url.protocol === 'http:' ? require('http').get : require('https').get;

        handler(input, (response: IncomingMessage) => {
          if (response.statusCode !== 200) {
            return reject(`Unexpected status code: ${response.statusCode}.`);
          }

          const stream = createWriteStream(output);

          stream.once('error', (error) => {
            return reject(error);
          });

          response.on('data', (chunk) => {
            stream.write(chunk);
          });

          response.once('end', () => {
            stream.end(() => {
              return resolve(url.pathname.split('/').pop());
            });
          });
        });
      }
    });
  }

  /**
   * Returns a list of additional Chromium flags recommended for serverless environments.
   * The canonical list of flags can be found on https://peter.sh/experiments/chromium-command-line-switches/.
   */
  static get args(): string[] {
    const result = [
      '--allow-running-insecure-content', // https://source.chromium.org/search?q=lang:cpp+symbol:kAllowRunningInsecureContent&ss=chromium
      '--autoplay-policy=user-gesture-required', // https://source.chromium.org/search?q=lang:cpp+symbol:kAutoplayPolicy&ss=chromium
      '--disable-background-timer-throttling',
      '--disable-component-update', // https://source.chromium.org/search?q=lang:cpp+symbol:kDisableComponentUpdate&ss=chromium
      '--disable-domain-reliability', // https://source.chromium.org/search?q=lang:cpp+symbol:kDisableDomainReliability&ss=chromium
      '--disable-features=AudioServiceOutOfProcess,IsolateOrigins,site-per-process', // https://source.chromium.org/search?q=file:content_features.cc&ss=chromium
      '--disable-ipc-flooding-protection',
      '--disable-print-preview', // https://source.chromium.org/search?q=lang:cpp+symbol:kDisablePrintPreview&ss=chromium
      '--disable-dev-shm-usage',
      '--disable-setuid-sandbox', // https://source.chromium.org/search?q=lang:cpp+symbol:kDisableSetuidSandbox&ss=chromium
      '--disable-site-isolation-trials', // https://source.chromium.org/search?q=lang:cpp+symbol:kDisableSiteIsolation&ss=chromium
      '--disable-speech-api', // https://source.chromium.org/search?q=lang:cpp+symbol:kDisableSpeechAPI&ss=chromium
      '--disable-web-security', // https://source.chromium.org/search?q=lang:cpp+symbol:kDisableWebSecurity&ss=chromium
      '--disk-cache-size=33554432', // https://source.chromium.org/search?q=lang:cpp+symbol:kDiskCacheSize&ss=chromium
      '--enable-features=SharedArrayBuffer', // https://source.chromium.org/search?q=file:content_features.cc&ss=chromium
      '--hide-scrollbars', // https://source.chromium.org/search?q=lang:cpp+symbol:kHideScrollbars&ss=chromium
      '--ignore-gpu-blocklist', // https://source.chromium.org/search?q=lang:cpp+symbol:kIgnoreGpuBlocklist&ss=chromium
      '--in-process-gpu', // https://source.chromium.org/search?q=lang:cpp+symbol:kInProcessGPU&ss=chromium
      '--mute-audio', // https://source.chromium.org/search?q=lang:cpp+symbol:kMuteAudio&ss=chromium
      '--no-default-browser-check', // https://source.chromium.org/search?q=lang:cpp+symbol:kNoDefaultBrowserCheck&ss=chromium
      '--no-first-run',
      '--no-pings', // https://source.chromium.org/search?q=lang:cpp+symbol:kNoPings&ss=chromium
      '--no-sandbox', // https://source.chromium.org/search?q=lang:cpp+symbol:kNoSandbox&ss=chromium
      '--no-zygote', // https://source.chromium.org/search?q=lang:cpp+symbol:kNoZygote&ss=chromium
      '--use-gl=angle', // https://chromium.googlesource.com/chromium/src/+/main/docs/gpu/swiftshader.md
      '--use-angle=swiftshader', // https://chromium.googlesource.com/chromium/src/+/main/docs/gpu/swiftshader.md
      '--window-size=1920,1080', // https://source.chromium.org/search?q=lang:cpp+symbol:kWindowSize&ss=chromium
    ];

    if (Chromium.headless === true) {
      result.push('--single-process'); // https://source.chromium.org/search?q=lang:cpp+symbol:kSingleProcess&ss=chromium
    } else {
      result.push('--start-maximized'); // https://source.chromium.org/search?q=lang:cpp+symbol:kStartMaximized&ss=chromium
    }

    return result;
  }

  /**
   * Returns sensible default viewport settings.
   */
  static get defaultViewport(): Required<Viewport> {
    return {
      deviceScaleFactor: 1,
      hasTouch: false,
      height: 1080,
      isLandscape: true,
      isMobile: false,
      width: 1920,
    };
  }

  /**
   * Inflates the current version of Chromium and returns the path to the binary.
   * If not running on AWS Lambda nor Google Cloud Functions, `null` is returned instead.
   */
  static get executablePath(): Promise<string> {
    if (Chromium.headless !== true) {
      return Promise.resolve(null);
    }

    if (existsSync('/tmp/chromium') === true) {
      for (const file of readdirSync('/tmp')) {
        if (file.startsWith('core.chromium') === true) {
          unlinkSync(`/tmp/${file}`);
        }
      }

      return Promise.resolve('/tmp/chromium');
    }

    const input = join(__dirname, '..', 'bin');
    const promises = [
      LambdaFS.inflate(`${input}/chromium.br`),
      LambdaFS.inflate(`${input}/swiftshader.tar.br`),
    ];

    if (/^AWS_Lambda_nodejs(?:10|12|14|16)[.]x$/.test(process.env.AWS_EXECUTION_ENV) === true) {
      promises.push(LambdaFS.inflate(`${input}/aws.tar.br`));
    }

    return Promise.all(promises).then((result) => result.shift());
  }

  /**
   * Returns a boolean indicating if we are running on AWS Lambda or Google Cloud Functions.
   * True is returned if the NODE_ENV is set to 'test' for easier integration testing.
   * False is returned if Serverless environment variables `IS_LOCAL` or `IS_OFFLINE` are set.
   */
  static get headless() {
    if (process.env.IS_LOCAL !== undefined || process.env.IS_OFFLINE !== undefined) {
      return false;
    }
    if (process.env.NODE_ENV === "test") {
      return true;
    }
    const environments = [
      'AWS_LAMBDA_FUNCTION_NAME',
      'FUNCTION_NAME',
      'FUNCTION_TARGET',
      'FUNCTIONS_EMULATOR',
    ];

    return environments.some((key) => process.env[key] !== undefined);
  }
}

export = Chromium;