Web App Live Updater

WALU is a library to add live update capabilities to your web application. It works by checking for update binaries and a version file on your server, downloading the update to a storage of your choice, validating it using RSA signatures, and applying the update by starting a service worker that replaces the current page with the updated version.

Note that this library does work in normal web browsers, but it is primarily designed for use in WebView-based applications, such as those built with Electron, Tauri, or Capacitor.

Features

• Check for updates from a specified server
• Ask for a single <update>.bundle file for manual updating, development or downgrading.
• Checks SHA-256 hash of the downloaded file against the version file.
• Checks RSA signature of the version file against a provided public key.
• Provides status callbacks for implementing a progress bar or similar.
• Uses a service worker to apply the update by reloading the page with the new content.
• Supports custom storage mechanisms for the downloaded update (e.g., IndexedDB, localStorage, capacitor Filesystem, etc.)
• Easy to integrate into existing web applications.

Installation

npm install @scolastico-dev/walu
# or unstable
npm install @scolastico-dev/walu@git+ssh://github.com/scolastico-dev/walu.git

Usage

Add the following code to your application startup code:

import { WaluConfig, installWalu } from '@scolastico-dev/walu';

installWalu(new WaluConfig(
  workerPath: '/walu-worker.js',
  publicKey: [
    '-----BEGIN PUBLIC KEY-----',
    'MIIBIjANBgkqhkiG9w0BAQEFAAOCA',
    '[...your rsa public key...]',
    '-----END PUBLIC KEY-----',
  ].join('\n'),
  apiUrls: {
    versionJson: 'https://example.com/path/to/version.json',
    updateBin: 'https://example.com/path/to/update.bin',
  },
)).then(() => {});

Make sure to host the walu-worker.js so it is accessible at the path you specify in workerPath.

npx @scolastico-dev/walu worker ./public/walu-worker.js

To achieve this, we recommend adding the command to your package.json scripts:

{
  "scripts": {
    "postinstall": "walu worker ./public/walu-worker.js"
  }
}

See the documentation for a full list of available options and functions: https://scolastico-dev.github.io/walu/

Publish a version

npx @scolastico-dev/walu key --help
# npx @scolastico-dev/walu key <privateKeyFile> <publicKeyFile>

npx @scolastico-dev/walu publish --help
# npx @scolastico-dev/walu publish <version> <privateKeyFile> <sourceDir> <outputDir>

### e.g.
npx @scolastico-dev/walu key key.pem key.pub
npx @scolastico-dev/walu publish 1.0.0 ./key.pem ./dist ./update