Micro Frontends Architecture with Module Federation · Aula

Módulos singleton e controle de versões

Compreenda como garantir que apenas uma instância de um módulo seja carregada e como gerenciar conflitos de versões.

Módulos singleton e controle de versões é uma aula grátis de Micro Frontends Architecture with Module Federation no CoddyKit. Esta é a aula 2 de 4. Você pode ler a aula completa abaixo gratuitamente — depois pratica ao vivo no navegador com um editor de código integrado e um tutor de IA 24/7. Faz parte do caminho de aprendizado de Micro Frontends Architecture with Module Federation, e seu progresso é sincronizado entre a web e o app CoddyKit. O curso de Micro Frontends Architecture with Module Federation inclui 4 aulas no total.

Partes desta aula ainda não foram traduzidas e aparecem em inglês.

What are Singleton Modules?

In Micro Frontend architectures, a singleton module is a piece of code or a library that should only ever exist as a single instance across your entire application, even if multiple Micro Frontends try to load it.

Think of it as a unique resource that all parts of your system need to share consistently.

Ensures a single source of truth.
Prevents conflicting states or behaviors.

Why Singletons Matter for MFEs

Imagine multiple Micro Frontends (MFEs) all loading their own copy of a UI library like React, or a state management library like Redux.

Without singletons, you could end up with:

Multiple instances of React Context, breaking component communication.
Separate Redux stores, leading to inconsistent application state.
Increased bundle size due to duplicate code.

Singletons solve these issues by guaranteeing a unified dependency.

Implementing Singletons with MF

Module Federation makes it easy to declare shared modules as singletons using the singleton: true option in your Webpack configuration.

When this is set, Webpack ensures that only one version of the specified module is loaded and used by all federated applications (hosts and remotes) at runtime.

Code: Configuring a Singleton

Here's how you'd configure a shared module, like react, to be a singleton in your webpack.config.js:

const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  // ... other Webpack config
  plugins: [
    new ModuleFederationPlugin({
      name: 'host_app',
      remotes: {},
      shared: {
        react: {
          singleton: true, // Only one React instance allowed
          requiredVersion: '^18.0.0',
        },
        'react-dom': {
          singleton: true, // Only one ReactDOM instance allowed
          requiredVersion: '^18.0.0',
        },
      },
    }),
  ],
};

Understanding Shared Module Versioning

Beyond ensuring a single *instance* (singleton), you also need to manage which *version* of a shared module gets loaded.

What if one MFE needs React v17 and another needs React v18? Module Federation has mechanisms to handle these version conflicts and ensure compatibility or gracefully fail.

`requiredVersion` for Specificity

The requiredVersion option in the shared configuration allows you to specify the semantic version (semver) range that your application expects for a shared module.

Webpack will try to find a compatible version among the host and remote applications. If a compatible version is found, it's used. If not, it might load a fallback or throw an error, depending on other settings.

Code: Specifying Required Versions

Here's how you might define a requiredVersion for a shared library:

const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  // ...
  plugins: [
    new ModuleFederationPlugin({
      // ...
      shared: {
        lodash: {
          singleton: false,
          requiredVersion: '^4.17.21', // Any version compatible with 4.17.21
        },
        moment: {
          singleton: true,
          requiredVersion: '2.29.1', // Exactly version 2.29.1
        },
      },
    }),
  ],
};

`strictVersion: true` for Strictness

While requiredVersion guides version selection, strictVersion: true enforces it rigorously.

If strictVersion: true is enabled and a remote module requests a version that is incompatible with the host's requiredVersion (or the version already loaded), Module Federation will throw an error and prevent the application from loading. This prevents unexpected behavior from version mismatches.

Code: Enforcing Strict Versioning

Combining singleton, requiredVersion, and strictVersion for critical dependencies:

const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  // ...
  plugins: [
    new ModuleFederationPlugin({
      // ...
      shared: {
        react: {
          singleton: true,
          requiredVersion: '^18.0.0',
          strictVersion: true, // Fail if versions are incompatible
        },
        // ... other shared modules
      },
    }),
  ],
};

Best Practices for Shared Dependencies

To effectively manage singleton modules and versioning:

Use Semantic Versioning (SemVer): Adhere to major.minor.patch for all shared modules.
Communicate: Ensure teams are aware of shared module updates and version requirements.
Test Compatibility: Regularly test your federated applications to ensure shared modules work across all remotes and hosts.
Be Strategic: Not all shared modules need to be singletons or have strict versioning. Apply these settings thoughtfully based on the module's criticality.

Quick Check: Singleton & Versioning

When configuring shared modules in Module Federation, what are the primary benefits of using singleton: true and strictVersion: true?

Recap & Next Steps

You've now learned about singleton modules and versioning in Module Federation!

Singleton modules ensure only one instance of a shared dependency exists across your federated application, crucial for stateful libraries.
The requiredVersion and strictVersion options help manage compatibility and prevent issues arising from conflicting module versions.

These techniques are vital for building robust and predictable Micro Frontend applications.

Perguntas Frequentes

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O que vou aprender em “Módulos singleton e controle de versões”?

Compreenda como garantir que apenas uma instância de um módulo seja carregada e como gerenciar conflitos de versões. Você pratica Micro Frontends Architecture with Module Federation com código prático que executa diretamente no navegador, e um tutor de IA 24/7 responde suas dúvidas enquanto trabalha na aula.

Preciso ter experiência prévia para começar Micro Frontends Architecture with Module Federation?

Nenhuma experiência prévia é necessária. Micro Frontends Architecture with Module Federation no CoddyKit é estruturado para alunos iniciantes até avançados, então você pode começar aqui ou desde o início e aprender no seu ritmo. Esta é a aula 2 de 4.

Quanto tempo leva a aula “Módulos singleton e controle de versões”?

A maioria das aulas CoddyKit leva cerca de 5–10 minutos. Cada uma é compacta e interativa, então você faz progresso constante e retoma exatamente de onde parou entre web e app.

Posso escrever e executar código nesta aula de Micro Frontends Architecture with Module Federation?

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Todas as aulas deste curso

Consumo de dependências compartilhadas
Módulos singleton e controle de versões
Carregamento dinâmico de módulos
Compartilhando Estado e Utilitários entre Remotos

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