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Módulos Nativos do NodeJS

Módulos Node,js nativos são suportados pelo Electron, mas, como Electron tem uma interface binária de aplicação (ABI) diferente da interface do Node.js (devido a diferenças como o uso do BoringSSL do Chromium ao invés do OpenSSL), os módulos nativos que você usar precisam ser recompilados para Electron. Caso contrário, você receberá a seguinte classe de erro quando tentar executar o seu aplicativo:

Error: The module '/path/to/native/module.node'
was compiled against a different Node.js version using
NODE_MODULE_VERSION $XYZ. This version of Node.js requires
NODE_MODULE_VERSION $ABC. Please try re-compiling or re-installing
the module (for instance, using `npm rebuild` or `npm install`).

Como instalar módulos nativos​

Existem várias maneiras diferentes de instalar módulos nativos:

Instalando módulos e recopilando para Electron​

Você pode instalar módulos igual em outros projetos em Node, e então recompilar os módulos para Electron com o pacote @electron/rebuild. Este módulo pode determinar automaticamente a versão do Electron e lidar com os passos manuais de baixar cabeçalhos e recompilar os módulos nativos para sua aplicação. Se você estiver usando o Electron Forge, esta ferramenta é usada automaticamente no modo de desenvolvimento e quando gera a distribuição.

Por exemplo, para instalar a ferramenta standalone @electron/rebuild e então reconstruir módulos com ela via linha de comando:

npm install --save-dev @electron/rebuild

# Every time you run "npm install", run this:
./node_modules/.bin/electron-rebuild

# If you have trouble on Windows, try:
.\node_modules\.bin\electron-rebuild.cmd

Para mais informações sobre uso e integração com outras ferramentas como Electron Packager, consulte o README do projeto.

Usando npm​

Definindo algumas variáveis de ambiente, você pode usar npm para instalar módulos diretamente.

Por exemplo, para instalar todas as dependências para Electron:

# Versão do Electron.
export npm_config_target=1.2.3
# The architecture of your machine
export npm_config_arch=x64
export npm_config_target_arch=x64
# Download headers for Electron.
export npm_config_disturl=https://electronjs.org/headers 
# Diga ao node-pre-gyp que estamos copilando para o Electron.
export npm_config_runtime=electron 
# Diga ao node-pre-gyp para copilar os módulos do código fonte.
export npm_config_build_from_source=true
# Instale todas as dependências e armazene cache para ~/.electron-gyp.
HOME=~/.electron-gyp npm install

Compilação Manual para o Electron​

Se você é um desenvolvedor que desenvolve um módulo nativo e quer testá-lo contra o Electron, você pode querer recompilar o módulo do Electron manualmente. Você pode usar node-gyp diretamente para compilar para Electron:

cd /path-to-module/
HOME=~/.electron-gyp node-gyp rebuild --target=1.2.3 --arch=x64 --dist-url=https://electronjs.org/headers
  • HOME=~/.electron-gyp changes where to find development headers.
  • --target=1.2.3 is the version of Electron.
  • --dist-url=... specifies where to download the headers.
  • --arch=x64 says the module is built for a 64-bit system.

Manually building for a custom build of Electron​

To compile native Node modules against a custom build of Electron that doesn't match a public release, instruct npm to use the version of Node you have bundled with your custom build.

npm rebuild --nodedir=/path/to/src/out/Default/gen/node_headers

Solução de Problemas​

If you installed a native module and found it was not working, you need to check the following things:

  • When in doubt, run @electron/rebuild first.
  • Make sure the native module is compatible with the target platform and architecture for your Electron app.
  • Make sure win_delay_load_hook is not set to false in the module's binding.gyp.
  • After you upgrade Electron, you usually need to rebuild the modules.

A note about win_delay_load_hook​

On Windows, by default, node-gyp links native modules against node.dll. However, in Electron 4.x and higher, the symbols needed by native modules are exported by electron.exe, and there is no node.dll. In order to load native modules on Windows, node-gyp installs a delay-load hook that triggers when the native module is loaded, and redirects the node.dll reference to use the loading executable instead of looking for node.dll in the library search path (which would turn up nothing). As such, on Electron 4.x and higher, 'win_delay_load_hook': 'true' is required to load native modules.

If you get an error like Module did not self-register, or The specified procedure could not be found, it may mean that the module you're trying to use did not correctly include the delay-load hook. If the module is built with node-gyp, ensure that the win_delay_load_hook variable is set to true in the binding.gyp file, and isn't getting overridden anywhere. If the module is built with another system, you'll need to ensure that you build with a delay-load hook installed in the main .node file. Your link.exe invocation should look like this:

 link.exe /OUT:"foo.node" "...\node.lib" delayimp.lib /DELAYLOAD:node.exe /DLL
     "my_addon.obj" "win_delay_load_hook.obj"

In particular, it's important that:

  • you link against node.lib from Electron and not Node. If you link against the wrong node.lib you will get load-time errors when you require the module in Electron.
  • you include the flag /DELAYLOAD:node.exe. If the node.exe link is not delayed, then the delay-load hook won't get a chance to fire and the node symbols won't be correctly resolved.
  • win_delay_load_hook.obj is linked directly into the final DLL. If the hook is set up in a dependent DLL, it won't fire at the right time.

See node-gyp for an example delay-load hook if you're implementing your own.

Modules that rely on prebuild​

prebuild provides a way to publish native Node modules with prebuilt binaries for multiple versions of Node and Electron.

If the prebuild-powered module provide binaries for the usage in Electron, make sure to omit --build-from-source and the npm_config_build_from_source environment variable in order to take full advantage of the prebuilt binaries.

Modules that rely on node-pre-gyp​

The node-pre-gyp tool provides a way to deploy native Node modules with prebuilt binaries, and many popular modules are using it.

Sometimes those modules work fine under Electron, but when there are no Electron-specific binaries available, you'll need to build from source. Because of this, it is recommended to use @electron/rebuild for these modules.

If you are following the npm way of installing modules, you'll need to pass --build-from-source to npm, or set the npm_config_build_from_source environment variable.