Electron Incremental Update

This project is built on top of vite-plugin-electron, offers a lightweight update solution for Electron applications without using native executables.

Key Features

The solution includes a Vite plugin, a startup entry function, an Updater class, and a set of utilities for Electron.

It use 2 asar file structure for updates:

• app.asar: The application entry, loads the ${electron.app.name}.asar and initializes the updater on startup
• ${electron.app.name}.asar: The package that contains main / preload / renderer process code

Update Steps

1. Check update from remote server
2. If update available, download the update asar, verify by presigned RSA + Signature and write to disk
3. Quit and restart the app
4. Replace the old ${electron.app.name}.asar on startup and load the new one

Other Features

• Update size reduction: All native modules should be packaged into app.asar to reduce ${electron.app.name}.asar file size, see usage
• Bytecode protection: Use V8 cache to protect source code, see details

Getting Started

Install

npm install -D electron-incremental-update

yarn add -D electron-incremental-update

pnpm add -D electron-incremental-update

Project Structure

Base on electron-vite-vue

electron
├── entry.ts // <- entry file
├── main
│   └── index.ts
├── preload
│   └── index.ts
└── native // <- possible native modules
    └── index.ts
src
└── ...

Setup Entry

The entry is used to load the application and initialize the Updater

Updater use the provider to check and download the update. The built-in GithubProvider is based on BaseProvider, which implements the IProvider interface (see types). And the provider is optional, you can setup later

in electron/entry.ts

import { createElectronApp } from 'electron-incremental-update'
import { GitHubProvider } from 'electron-incremental-update/provider'

createElectronApp({
  updater: {
    // optinal, you can setup later
    provider: new GitHubProvider({
      username: 'yourname',
      repo: 'electron',
    }),
  },
  beforeStart(mainFilePath, logger) {
    logger?.debug(mainFilePath)
  },
})

• some Github CDN resources

Setup vite.config.ts

The plugin config, main and preload parts are reference from electron-vite-vue

• certificate will read from process.env.UPDATER_CERT first, if absend, read config
• privatekey will read from process.env.UPDATER_PK first, if absend, read config

See all config in types

in vite.config.mts

import { debugStartup, electronWithUpdater } from 'electron-incremental-update/vite'
import { defineConfig } from 'vite'

export default defineConfig(async ({ command }) => {
  const isBuild = command === 'build'
  return {
    plugins: [
      electronWithUpdater({
        isBuild,
        logParsedOptions: true,
        main: {
          files: ['./electron/main/index.ts', './electron/main/worker.ts'],
          // see https://github.com/electron-vite/electron-vite-vue/blob/85ed267c4851bf59f32888d766c0071661d4b94c/vite.config.ts#L22-L28
          onstart: debugStartup,
        },
        preload: {
          files: './electron/preload/index.ts',
        },
        updater: {
          // options
        }
      }),
    ],
    server: process.env.VSCODE_DEBUG && (() => {
      const url = new URL(pkg.debug.env.VITE_DEV_SERVER_URL)
      return {
        host: url.hostname,
        port: +url.port,
      }
    })(),
  }
})

Modify package.json

{
  "main": "dist-entry/entry.js" // <- entry file path
}

Config electron-builder

const { name } = require('./package.json')

const targetFile = `${name}.asar`
/**
 * @type {import('electron-builder').Configuration}
 */
module.exports = {
  appId: 'YourAppID',
  productName: name,
  files: [
    // entry files
    'dist-entry',
  ],
  npmRebuild: false,
  asarUnpack: [
    '**/*.{node,dll,dylib,so}',
  ],
  directories: {
    output: 'release',
  },
  extraResources: [
    { from: `release/${targetFile}`, to: targetFile }, // <- asar file
  ],
  // disable publish
  publish: null,
}

Usage

Use In Main Process

In most cases, you should also setup the UpdateProvider before updating, unless you setup params when calling checkUpdate or downloadUpdate.

The update steps are similar to electron-updater and have same methods and events on Updater

NOTE: There should only one function and should be default export in the main index file

in electron/main/index.ts

import { app } from 'electron'
import { startupWithUpdater, UpdaterError } from 'electron-incremental-update'
import { getPathFromAppNameAsar, getVersions } from 'electron-incremental-update/utils'

export default startupWithUpdater((updater) => {
  await app.whenReady()

  console.table({
    [`${app.name}.asar path:`]: getPathFromAppNameAsar(),
    'app version:': getAppVersion(),
    'entry (installer) version:': getEntryVersion(),
    'electron version:': process.versions.electron,
  })

  updater.onDownloading = ({ percent }) => {
    console.log(percent)
  }
  updater.logger = console
  updater.receiveBeta = true
  // setup provider later
  updater.provider = new GitHubProvider({
    user: 'yourname',
    repo: 'electron',
    // setup url handler
    urlHandler: (url) => {
      url.hostname = 'mirror.ghproxy.com'
      url.pathname = `https://github.com${url.pathname}`
      return url
    }
  })

  updater.on('update-available', async ({ version }) => {
    const { response } = await dialog.showMessageBox({
      type: 'info',
      buttons: ['Download', 'Later'],
      message: `v${version} update available!`,
    })
    if (response !== 0) {
      return
    }
    await updater.downloadUpdate()
  })
  updater.on('update-not-available', (code, reason, info) => console.log(code, reason, info))
  updater.on('download-progress', (data) => {
    console.log(data)
    main.send(BrowserWindow.getAllWindows()[0], 'msg', data)
  })
  updater.on('update-downloaded', () => {
    updater.quitAndInstall()
  })
  updater.checkForUpdates()
})

Use Native Modules

To reduce production size, it is recommended that all the native modules should be set as dependency in package.json and other packages should be set as devDependencies. Also, electron-rebuild only check dependencies inside dependency field.

If you are using electron-builder to build distributions, all the native modules with its large relavent node_modiles will be packaged into app.asar by default.

Luckily, Esbuild can bundle all the dependencies. Just follow the steps:

1. setup nativeModuleEntryMap option
2. Manually copy the native binaries in postBuild callback
3. Exclude all the dependencies in electron-builder's config
4. call the native functions with requireNative / importNative in your code

Example

in vite.config.ts

const plugin = electronWithUpdater({
  // options...
  updater: {
    entry: {
      nativeModuleEntryMap: {
        db: './electron/native/db.ts',
        img: './electron/native/img.ts',
      },
      postBuild: async ({ copyToEntryOutputDir, copyModules }) => {
        // for better-sqlite3
        copyToEntryOutputDir({
          from: './node_modules/better-sqlite3/build/Release/better_sqlite3.node',
          skipIfExist: false,
        })
        // for @napi-rs/image
        const startStr = '@napi-rs+image-'
        const fileName = (await readdir('./node_modules/.pnpm')).filter(p => p.startsWith(startStr))[0]
        const archName = fileName.substring(startStr.length).split('@')[0]
        copyToEntryOutputDir({
          from: `./node_modules/.pnpm/${fileName}/node_modules/@napi-rs/image-${archName}/image.${archName}.node`,
        })
        // or just copy specific dependency
        copyModules({ modules: ['better-sqlite3'] })
      },
    },
  },
})

in electron/native/db.ts

import Database from 'better-sqlite3'
import { getPathFromEntryAsar } from 'electron-incremental-update/utils'

const db = new Database(':memory:', { nativeBinding: getPathFromEntryAsar('./better_sqlite3.node') })

export function test(): void {
  db.exec(
    'DROP TABLE IF EXISTS employees; '
    + 'CREATE TABLE IF NOT EXISTS employees (name TEXT, salary INTEGER)',
  )

  db.prepare('INSERT INTO employees VALUES (:n, :s)').run({
    n: 'James',
    s: 5000,
  })

  const r = db.prepare('SELECT * from employees').all()
  console.log(r)
  // [ { name: 'James', salary: 50000 } ]

  db.close()
}

in electron/main/service.ts

import { importNative, requireNative } from 'electron-incremental-update/utils'

// commonjs
requireNative<typeof import('../native/db')>('db').test()

// esm
importNative<typeof import('../native/db')>('db').test()

in electron-builder.config.js

module.exports = {
  files: [
    'dist-entry',
    // exclude all dependencies in electron-builder config
    '!node_modules/**',
  ]
}

Bytecode Protection

Use V8 cache to protect the source code

electronWithUpdater({
  // ...
  bytecode: true, // or options
})

Benifits

https://electron-vite.org/guide/source-code-protection

• Improve the string protection (see original issue)
• Protect all strings by default
• Minification is allowed

Limitation

• Only support commonjs
• Only for main process by default, if you want to use in preload script, please use electronWithUpdater({ bytecode: { enablePreload: true } }) and set sandbox: false when creating window

Utils

/**
 * Compile time dev check
 */
const isDev: boolean
const isWin: boolean
const isMac: boolean
const isLinux: boolean
/**
 * Get joined path of `${electron.app.name}.asar` (not `app.asar`)
 *
 * If is in dev, **always** return `'DEV.asar'`
 */
function getPathFromAppNameAsar(...paths: string[]): string
/**
 * Get app version, if is in dev, return `getEntryVersion()`
 */
function getAppVersion(): string
/**
 * Get entry version
 */
function getEntryVersion(): string
/**
 * Use `require` to load native module from entry asar
 * @param moduleName file name in entry
 * @example
 * requireNative<typeof import('../native/db')>('db')
 */
function requireNative<T = any>(moduleName: string): T
/**
 * Use `import` to load native module from entry asar
 * @param moduleName file name in entry
 * @example
 * await importNative<typeof import('../native/db')>('db')
 */
function importNative<T = any>(moduleName: string): Promise<T>
/**
 * Restarts the Electron app.
 */
function restartApp(): void
/**
 * Fix app use model id, only for Windows
 * @param id app id, default is `org.${electron.app.name}`
 */
function setAppUserModelId(id?: string): void
/**
 * Disable hardware acceleration for Windows 7
 *
 * Only support CommonJS
 */
function disableHWAccForWin7(): void
/**
 * Keep single electron instance and auto restore window on `second-instance` event
 * @param window brwoser window to show
 */
function singleInstance(window?: BrowserWindow): void
/**
 * Set `AppData` dir to the dir of .exe file
 *
 * Useful for portable Windows app
 * @param dirName dir name, default to `data`
 */
function setPortableAppDataPath(dirName?: string): void
/**
 * Load `process.env.VITE_DEV_SERVER_URL` when dev, else load html file
 * @param win window
 * @param htmlFilePath html file path, default is `index.html`
 */
function loadPage(win: BrowserWindow, htmlFilePath?: string): void
interface BeautifyDevToolsOptions {
  /**
   * Sans-serif font family
   */
  sans: string
  /**
   * Monospace font family
   */
  mono: string
  /**
   * Whether to round scrollbar
   */
  scrollbar?: boolean
}
/**
 * Beautify devtools' font and scrollbar
 * @param win target window
 * @param options sans font family, mono font family and scrollbar
 */
function beautifyDevTools(win: BrowserWindow, options: BeautifyDevToolsOptions): void
/**
 * Get joined path from main dir
 * @param paths rest paths
 */
function getPathFromMain(...paths: string[]): string
/**
 * Get joined path from preload dir
 * @param paths rest paths
 */
function getPathFromPreload(...paths: string[]): string
/**
 * Get joined path from publich dir
 * @param paths rest paths
 */
function getPathFromPublic(...paths: string[]): string
/**
 * Get joined path from entry asar
 * @param paths rest paths
 */
function getPathFromEntryAsar(...paths: string[]): string
/**
 * Handle all unhandled error
 * @param callback callback function
 */
function handleUnexpectedErrors(callback: (err: unknown) => void): void
/**
 * Safe get value from header
 * @param headers response header
 * @param key target header key
 */
function getHeader(headers: Record<string, Arrayable<string>>, key: any): any
function downloadUtil<T>(
  url: string,
  headers: Record<string, any>,
  signal: AbortSignal,
  onResponse: (
    resp: IncomingMessage,
    resolve: (data: T) => void,
    reject: (e: any) => void
  ) => void
): Promise<T>
/**
 * Default function to download json and parse to UpdateJson
 * @param url target url
 * @param headers extra headers
 * @param signal abort signal
 * @param resolveData on resolve
 */
function defaultDownloadJSON<T>(
  url: string,
  headers: Record<string, any>,
  signal: AbortSignal,
  resolveData?: ResolveDataFn
): Promise<T>
/**
 * Default function to download json and parse to UpdateJson
 * @param url target url
 * @param headers extra headers
 * @param signal abort signal
 */
function defaultDownloadUpdateJSON(
  url: string,
  headers: Record<string, any>,
  signal: AbortSignal
): Promise<UpdateJSON>
/**
 * Default function to download asar buffer,
 * get total size from `Content-Length` header
 * @param url target url
 * @param headers extra headers
 * @param signal abort signal
 * @param onDownloading on downloading callback
 */
function defaultDownloadAsar(
  url: string,
  headers: Record<string, any>,
  signal: AbortSignal,
  onDownloading?: (progress: DownloadingInfo) => void
): Promise<Buffer>

Types

Entry

export interface AppOption {
  /**
   * Path to index file that make {@link startupWithUpdater} as default export
   *
   * Generate from plugin configuration by default
   */
  mainPath?: string
  /**
   * Updater options
   */
  updater?: (() => Promisable<Updater>) | UpdaterOption
  /**
   * Hooks on rename temp asar path to `${app.name}.asar`
   */
  onInstall?: OnInstallFunction
  /**
   * Hooks before app startup
   * @param mainFilePath main file path of `${app.name}.asar`
   * @param logger logger
   */
  beforeStart?: (mainFilePath: string, logger?: Logger) => Promisable<void>
  /**
   * Hooks on app startup error
   * @param err installing or startup error
   * @param logger logger
   */
  onStartError?: (err: unknown, logger?: Logger) => void
}
/**
 * Hooks on rename temp asar path to `${app.name}.asar`
 * @param install `() => renameSync(tempAsarPath, appNameAsarPath)`
 * @param tempAsarPath temp(updated) asar path
 * @param appNameAsarPath `${app.name}.asar` path
 * @param logger logger
 * @default install(); logger.info('update success!')
 */
type OnInstallFunction = (
  install: VoidFunction,
  tempAsarPath: string,
  appNameAsarPath: string,
  logger?: Logger
) => Promisable<void>

Updater

export interface UpdaterOption {
  /**
   * Update provider
   *
   * If you will not setup `UpdateJSON` or `Buffer` in params when checking update or download, this option is **required**
   */
  provider?: IProvider
  /**
   * Certifaction key of signature, which will be auto generated by plugin,
   * generate by `selfsigned` if not set
   */
  SIGNATURE_CERT?: string
  /**
   * Whether to receive beta update
   */
  receiveBeta?: boolean
  /**
   * Updater logger
   */
  logger?: Logger
}

export type Logger = {
  info: (msg: string) => void
  debug: (msg: string) => void
  warn: (msg: string) => void
  error: (msg: string, e?: Error) => void
}

Provider

export type OnDownloading = (progress: DownloadingInfo) => void

export interface DownloadingInfo {
  /**
   * Download buffer delta
   */
  delta: number
  /**
   * Downloaded percent, 0 ~ 100
   *
   * If no `Content-Length` header, will be -1
   */
  percent: number
  /**
   * Total size
   *
   * If not `Content-Length` header, will be -1
   */
  total: number
  /**
   * Downloaded size
   */
  transferred: number
  /**
   * Download speed, bytes per second
   */
  bps: number
}

export interface IProvider {
  /**
   * Provider name
   */
  name: string
  /**
   * Download update json
   * @param versionPath parsed version path in project
   * @param signal abort signal
   */
  downloadJSON: (versionPath: string, signal: AbortSignal) => Promise<UpdateJSON>
  /**
   * Download update asar
   * @param name app name
   * @param updateInfo existing update info
   * @param signal abort signal
   * @param onDownloading hook for on downloading
   */
  downloadAsar: (
    name: string,
    updateInfo: UpdateInfo,
    signal: AbortSignal,
    onDownloading?: (info: DownloadingInfo) => void
  ) => Promise<Buffer>
  /**
   * Check the old version is less than new version
   * @param oldVer old version string
   * @param newVer new version string
   */
  isLowerVersion: (oldVer: string, newVer: string) => boolean
  /**
   * Function to decompress file using brotli
   * @param buffer compressed file buffer
   */
  unzipFile: (buffer: Buffer) => Promise<Buffer>
  /**
   * Verify asar signature,
   * if signature is valid, returns the version, otherwise returns `undefined`
   * @param buffer file buffer
   * @param version target version
   * @param signature signature
   * @param cert certificate
   */
  verifySignaure: (buffer: Buffer, version: string, signature: string, cert: string) => Promisable<boolean>
}

Plugin

export interface ElectronWithUpdaterOptions {
  /**
   * Whether is in build mode
   * ```ts
   * export default defineConfig(({ command }) => {
   *   const isBuild = command === 'build'
   * })
   * ```
   */
  isBuild: boolean
  /**
   * Manually setup package.json, read name, version and main,
   * use `local-pkg` of `loadPackageJSON()` to load package.json by default
   * ```ts
   * import pkg from './package.json'
   * ```
   */
  pkg?: PKG
  /**
   * Whether to generate sourcemap
   * @default !isBuild
   */
  sourcemap?: boolean
  /**
   * Whether to minify the code
   * @default isBuild
   */
  minify?: boolean
  /**
   * Whether to generate bytecode
   *
   * **Only support CommonJS**
   *
   * Only main process by default, if you want to use in preload script, please use `electronWithUpdater({ bytecode: { enablePreload: true } })` and set `sandbox: false` when creating window
   */
  bytecode?: boolean | BytecodeOptions
  /**
   * Use `NotBundle()` plugin in main
   * @default true
   */
  useNotBundle?: boolean
  /**
   * Whether to generate version json
   * @default isCI
   */
  buildVersionJson?: boolean
  /**
   * Whether to log parsed options
   *
   * To show certificate and private keys, set `logParsedOptions: { showKeys: true }`
   */
  logParsedOptions?: boolean | { showKeys: boolean }
  /**
   * Main process options
   *
   * To change output directories, use `options.updater.paths.electronDistPath` instead
   */
  main: MakeRequiredAndReplaceKey<ElectronSimpleOptions['main'], 'entry', 'files'> & ExcludeOutputDirOptions
  /**
   * Preload process options
   *
   * To change output directories, use `options.updater.paths.electronDistPath` instead
   */
  preload: MakeRequiredAndReplaceKey<Exclude<ElectronSimpleOptions['preload'], undefined>, 'input', 'files'> & ExcludeOutputDirOptions
  /**
   * Updater options
   */
  updater?: ElectronUpdaterOptions
}

export interface ElectronUpdaterOptions {
  /**
   * Minimum version of entry
   * @default '0.0.0'
   */
  minimumVersion?: string
  /**
   * Options for entry (app.asar)
   */
  entry?: BuildEntryOption
  /**
   * Options for paths
   */
  paths?: {
    /**
     * Path to asar file
     * @default `release/${app.name}.asar`
     */
    asarOutputPath?: string
    /**
     * Path to version info output, content is {@link UpdateJSON}
     * @default `version.json`
     */
    versionPath?: string
    /**
     * Path to gzipped asar file
     * @default `release/${app.name}-${version}.asar.gz`
     */
    gzipPath?: string
    /**
     * Path to electron build output
     * @default `dist-electron`
     */
    electronDistPath?: string
    /**
     * Path to renderer build output
     * @default `dist`
     */
    rendererDistPath?: string
  }
  /**
   * signature config
   */
  keys?: {
    /**
     * Path to the pem file that contains private key
     * If not ended with .pem, it will be appended
     *
     * **If `UPDATER_PK` is set, will read it instead of read from `privateKeyPath`**
     * @default 'keys/private.pem'
     */
    privateKeyPath?: string
    /**
     * Path to the pem file that contains public key
     * If not ended with .pem, it will be appended
     *
     * **If `UPDATER_CERT` is set, will read it instead of read from `certPath`**
     * @default 'keys/cert.pem'
     */
    certPath?: string
    /**
     * Length of the key
     * @default 2048
     */
    keyLength?: number
    /**
     * X509 certificate info
     *
     * only generate simple **self-signed** certificate **without extensions**
     */
    certInfo?: {
      /**
       * The subject of the certificate
       *
       * @default { commonName: `${app.name}`, organizationName: `org.${app.name}` }
       */
      subject?: DistinguishedName
      /**
       * Expire days of the certificate
       *
       * @default 3650
       */
      days?: number
    }
  }
  overrideGenerator?: GeneratorOverrideFunctions
}

export interface BytecodeOptions {
  enable: boolean
  /**
   * Enable in preload script. Remember to set `sandbox: false` when creating window
   */
  preload?: boolean
  /**
   * Custom electron binary path
   */
  electronPath?: string
  /**
   * Before transformed code compile function. If return `Falsy` value, it will be ignored
   * @param code transformed code
   * @param id file path
   */
  beforeCompile?: (code: string, id: string) => Promisable<string | null | undefined | void>
}

export interface BuildEntryOption {
  /**
   * Override to minify on entry
   * @default isBuild
   */
  minify?: boolean
  /**
   * Override to generate sourcemap on entry
   */
  sourcemap?: boolean
  /**
   * Path to app entry output file
   * @default 'dist-entry'
   */
  entryOutputDirPath?: string
  /**
   * Path to app entry file
   * @default 'electron/entry.ts'
   */
  appEntryPath?: string
  /**
   * Esbuild path map of native modules in entry directory
   *
   * @default {}
   * @example
   * { db: './electron/native/db.ts' }
   */
  nativeModuleEntryMap?: Record<string, string>
  /**
   * Skip process dynamic require
   *
   * Useful for `better-sqlite3` and other old packages
   */
  ignoreDynamicRequires?: boolean
  /**
   * `external` option in `build.rollupOptions`, external `.node` by default
   */
  external?: string | string[] | ((source: string, importer: string | undefined, isResolved: boolean) => boolean | null | undefined | void)
  /**
   * Custom options for `vite` build
   * ```ts
   * const options = {
   *   plugins: [esm(), bytecodePlugin()], // load on needed
   *   build: {
   *     sourcemap,
   *     minify,
   *     outDir: entryOutputDirPath,
   *     commonjsOptions: { ignoreDynamicRequires },
   *     rollupOptions: { external },
   *   },
   *   define,
   * }
   * ```
   */
  overrideViteOptions?: InlineConfig
  /**
   * Resolve extra files on startup, such as `.node`
   * @remark won't trigger will reload
   */
  postBuild?: (args: {
    /**
     * Get path from `entryOutputDirPath`
     */
    getPathFromEntryOutputDir: (...paths: string[]) => string
    /**
     * Check exist and copy file to `entryOutputDirPath`
     *
     * If `to` absent, set to `basename(from)`
     *
     * If `skipIfExist` absent, skip copy if `to` exist
     */
    copyToEntryOutputDir: (options: {
      from: string
      to?: string
      /**
       * Skip copy if `to` exist
       * @default true
       */
      skipIfExist?: boolean
    }) => void
    /**
     * Copy specified modules to entry output dir, just like `external` option in rollup
     */
    copyModules: (options: {
      /**
       * External Modules
       */
      modules: string[]
      /**
       * Skip copy if `to` exist
       * @default true
       */
      skipIfExist?: boolean
    }) => void
  }) => Promisable<void>
}

export interface GeneratorOverrideFunctions {
  /**
   * Custom signature generate function
   * @param buffer file buffer
   * @param privateKey private key
   * @param cert certificate string, **EOL must be '\n'**
   * @param version current version
   */
  generateSignature?: (
    buffer: Buffer,
    privateKey: string,
    cert: string,
    version: string
  ) => Promisable<string>
  /**
   * Custom generate update json function
   * @param existingJson The existing JSON object.
   * @param buffer file buffer
   * @param signature generated signature
   * @param version current version
   * @param minVersion The minimum version
   */
  generateUpdateJson?: (
    existingJson: UpdateJSON,
    signature: string,
    version: string,
    minVersion: string
  ) => Promisable<UpdateJSON>
  /**
   * Custom generate zip file buffer
   * @param buffer source buffer
   */
  generateGzipFile?: (buffer: Buffer) => Promisable<Buffer>
}

Credits

• Obsidian for upgrade strategy
• vite-plugin-electron for vite plugin
• electron-builder for update api
• electron-vite for bytecode plugin inspiration

License

MIT