originjs/vite-plugin-federation

vite-plugin-federation

A Vite/Rollup plugin which support Module Federation. Inspired by Webpack and compatible with Webpack Module Federation.

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Usage
Example projects
Features
Configuration
Add other example projects?
Runtime add remotes with virtual:__federation__
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Install

npm install @originjs/vite-plugin-federation --save-dev

yarn add @originjs/vite-plugin-federation --dev

Usage

Using the Module Federation usually requires more than 2 projects, one as the host side and one as the remote side.

Step 1: Configure the remote side.

for a vite project, modify vite.config.js:

// vite.config.js
import federation from "@originjs/vite-plugin-federation";
export default {
    plugins: [
        federation({
            name: 'remote-app',
            filename: 'remoteEntry.js',
            // Modules to expose
            exposes: {
                './Button': './src/Button.vue',
            },
            shared: ['vue']
        })
    ]
}

for a rollup project, modify rollup.config.js:

// rollup.config.js
import federation from '@originjs/vite-plugin-federation'
export default {
    input: 'src/index.js',
    plugins: [
        federation({
            name: 'remote-app',
            filename: 'remoteEntry.js',
            // Modules to expose
            exposes: {
                './Button': './src/button'.
            },
            shared: ['vue']
        })
    ]
}

Step 2: Configure the host side

for a vite project, modify vite.config.js:

// vite.config.js
import federation from "@originjs/vite-plugin-federation";
export default {
    plugins: [
        federation({
            name: 'host-app',
            remotes: {
                remote_app: "http://localhost:5001/assets/remoteEntry.js",
            },
            shared: ['vue']
        })
    ]
}

for a rollup project, modify rollup.config.js:

// rollup.config.js
import federation from '@originjs/vite-plugin-federation'
export default {
    input: 'src/index.js',
    plugins: [
        federation({
            name: 'host-app',
            remotes: {
                remote_app: "http://localhost:5001/remoteEntry.js",
            },
            shared: ['vue']
        })
    ]
}

Step 3: Using remote modules on the host side

Using a Vue project as an example

import { createApp, defineAsyncComponent } from "vue";
const app = createApp(Layout);
...
const RemoteButton = defineAsyncComponent(() => import("remote_app/Button"));
app.component("RemoteButton", RemoteButton);
app.mount("#root");

Using remote components in templates

<template>
    <div>
        <RemoteButton />
    </div>
</template>

Example projects

Examples	Host	Remote
basic-host-remote	`rollup`+`esm`	`rollup`+`esm`
react-in-vue	`vite`+`esm`	`vite`+`esm`
simple-react-esm	`rollup`+`esm`	`rollup`+`esm`
simple-react-systemjs	`rollup`+`systemjs`	`rollup`+`systemjs`
simple-react-webpack	`rollup`+`systemjs`	`webpack`+`systemjs`
vue2-demo	`vite`+`esm`	`vite`+`esm`
vue3-advanced-demo	`vite`+`esm` `vue-router`/`pinia`	`vite`+`esm` `vue-router`/`pinia`
vue3-demo-esm	`vite`+`esm`	`vite`+`esm`
vue3-demo-systemjs	`vite`+`systemjs`	`vite`+`systemjs`
vue3-demo-webpack-esm-esm	`vite/webpack`+`esm`	`vite/webpack`+`esm`
vue3-demo-webpack-esm-var	`vite`+`esm`	`webpack`+`var`
vue3-demo-webpack-systemjs	`vite`+`systemjs`	`webpack`+`systemjs`
react-vite	`vite`+`react`	`vite` + `react`

Features

Integration with Webpack

It is now possible to use Module Federation without the restrictions of Vite and Webpack! That is, you can choose to use the components exposed by vite-plugin-federation in Webpack or the components exposed by Webpack ModuleFederationPlugin in Vite. But you need to pay attention to the configuration in remotes, for different frameworks you need to specify remotes.from and remotes.format to make them work better. A couple of example projects can be found here.

⚠️ Note:

Vite is relatively easy to use with the Webpack component, but Webpack is best used with the vite-plugin-federation component using the esm format, as the other formats lack complete test cases for now.
It is not recommended to mix Vite and Webpack in React projects, as there is no guarantee that Vite/Rollup and Webpack will generate the same chunk when packaging commonjs, which may cause problems with shared.

Vite Dev mode

As Vite is built on esbuild in dev development mode, we provide separate support for dev mode to take advantage of Vite's high performance development server in the case of remote module deployment.

⚠️ Note:

Only the Host side supports dev mode, the Remote side requires the RemoteEntry.js package to be generated using vite build. This is because Vite Dev mode is Bundleless and you can use vite build --watch to achieve a hot update effect.

Static import

Static import and dynamic import of components are supported, the following shows the difference between the two methods, you can see examples of dynamic import and static import in the project in examples, here is a simple example.

// dynamic import
const myButton = defineAsyncComponent(() => import('remote/myButton'));
app.component('my-button' , myButton);
// or
export default {
  name: 'App',
  components: {
    myButton: () => import('remote/myButton'),
  }
}

// static import
import myButton from 'remote/myButton';
app.component('my-button' , myButton);
// or
export default {
  name: 'App',
  components: {
    myButton: myButton
  }
}

React

// dynamic import
const myButton = React.lazy(() => import('remote/myButton'))

// static import
import myButton from 'remote/myButton'

⚠️ Note:

Static imports may rely on the browser Top-level await feature, so you will need to set build.target in the configuration file to next or use the plugin vite-plugin-top-level-await. You can see the browser compatibility of top-level await here compatibility)

Configuration

`name: string`

Required as the module name of the remote module.

`filename:string`

As the entry file of the remote module, not required, default is remoteEntry.js

`transformFileTypes:string[]`

In most cases, the file types that the plug-in needs to process do not need to be configured, because these types are set by default.['.js', '.ts', '.jsx', '.tsx', '.mjs', '.cjs', '.vue', '.svelte'],When you customize some file types and need the vite-plugin-federation plugin processing, please add it to the array configuration.

`exposes`

As the remote module, the list of components exposed to the public, required for the remote module.

exposes: {
// 'externally exposed component name': 'externally exposed component address'
    './remote-simple-button': './src/components/Button.vue', 
    './remote-simple-section': './src/components/Section.vue'
},

If you need a more complex configuration

exposes: {
    './remote-simple-button': {
        import: './src/components/Button.vue',
        name: 'customChunkName',
        dontAppendStylesToHead: true
    },
},

The import property is the address of the module. If you need to specify a custom chunk name for the module use the name property.

The dontAppendStylesToHead property is used if you don't want the plugin to automatically append all styles of the exposed component to the <head> element, which is the default behavior. It's useful if your component uses a ShadowDOM and the global styles wouldn't affect it anyway. The plugin will then expose the addresses of the CSS files in the global window object, so that your exposed component can append the styles inside the ShadowDOM itself. The key under the window object used for styles will be css__{name_of_the_app}__{key_of_the_exposed_component}. In the above example it would be css__App__./remote-simple-button, assuming that the global name option (not the one under exposed component configuration) is App. The value under this key is an array of strings, which contains the addresses of CSS files. In your exposed component you can iterate over this array and manually create <link> elements with href attribute set to the elements of the array like this:

const styleContainer = document.createElement("div");
const hrefs = window["css__App__./remote-simple-button"];

hrefs.forEach((href: string) => {
    const link = document.createElement('link')
    link.href = href
    link.rel = 'stylesheet'
    styleContainer.appendChild(link);
});

`remotes`

The remote module entry file referenced as a local module

`external:string|Promise<string>`

remote module address, e.g. https://localhost:5011/remoteEntry.js
You can simply configure it as follows

  remotes: {
    // 'remote module name': 'remote module entry file address'
    'remote-simple': 'http://localhost:5011/remoteEntry.js',
}

Or do a slightly more complex configuration, if you need to use other fields

remotes: {
    remote-simple: {
        external: 'http://localhost:5011/remoteEntry.js',
        format: 'var',
    }
}

`externalType: 'url'|'promise'`

default: 'url'
Set the type of external. If you want to use a dynamic url address, you can set the external as promise, but please note that you need to set the externalType as 'promise' at the same time, and please ensure that the code of the promise part is correct, otherwise the package may fail,here is a simple example.

remotes: {
      home: {
          external: `Promise.resolve('your url')`,
          externalType: 'promise'
      },
},
    
// or from networke
remotes: {
    remote-simple: {
        external: `fetch('your url').then(response=>response.json()).then(data=>data.url)`,
        externalType: 'promise'
    }
}

`format:'esm'|'systemjs'|'var'`

default:'esm'
Specify the format of the remote component, this is more effective when the host and the remote use different packaging formats, for example the host uses vite + esm and the remote uses webpack + var, in which case you need to specify type : 'var'

`from` : `'vite'|'webpack'`

default : 'vite'
Specify the source of the remote component, from vite-plugin-federation select vite, from webpack select webpack

`shared`

Dependencies shared by local and remote modules. Local modules need to configure the dependencies of all used remote modules; remote modules need to configure the dependencies of externally provided components.

`import: boolean`

default: true
The default is true, whether to add shared to the module, only for the remote side, remote will reduce some of the packaging time when this configuration is turned on, because there is no need to package some of the shared, but once there is no shared module available on the host side, it will report an error directly, because there is no fallback module available

`shareScope: string`

default: 'default'
Default is default, the shared domain name, just keep the remote and host sides the same

`version: string`

Only works on host side, the version of the shared module provided is version of the package.json file in the shared package by default, you need to configure it manually only if you can't get version by this method

`requiredVersion: string`

Only for the remote side, it specifies the required version of the host shared used, when the version of the host side does not meet the requiredVersion requirement, it will use its own shared module, provided that it is not configured with import=false, which is not enabled by default

`packagePath: string`

supportMode: only serve
Allow custom packages to be shared via packagePath (previously limited to those under node_modules), For Example You can only define similar shared

shared :{
    packageName:{
        ...
    }
}

packageName must be a package under node_modules, such as vue, react, etc., but you cannot define your own package. But now you can share a custom package by specifying the package path, for example

shared: {
    packageName: {
        packagePath: './src/a/index.js'
    }
}

`generate : boolean`

default: true
generate a shared chunk file or not , if you make sure that the host side has a share that can be used, then you can set not to generate a shared file on the remote side to reduce the size of the remote's chunk file, which is only effective on the remote side, the host side will generate a shared chunk no matter what.

shared: {
    packageName: {
        generate: false
    }
}

`modulePreload : boolean`

default: false
if true, the shared dependency bundle file append to html head as link modulepreload, only work in prod mode.

shared: {
    packageName: {
        modulePreload: true
    }
}

Runtime add remotes with `virtual:federation`

It is not always possible to define the list of remote applications in advance in vite.config. Some applications may load the list of these remotes asynchronously when the user visits the website. In such cases, you can use the virtual:__federation__ API.

Note: This is a virtual module, for a deeper understanding of virtual modules in Vite, see: https://vite.dev/guide/api-plugin#virtual-modules-convention

API `virtual:federation`

Using methods from the virtual:__federation__ module, you can implement dynamic loading of a remote application.

import {
  __federation_method_getRemote as getRemote,
  __federation_method_setRemote as setRemote,
  __federation_method_unwrapDefault as unwrapModule,
  type IRemoteConfig,
} from "virtual:__federation__";

const renderComponent = () => {
  throw Error("Not implemented");
}

const loadCrmPlugins = async () => {
  try {
    const pluginsResponse = await fetch("some-backed.com/plugins");
    const pluginsJson = await pluginsResponse.json();
    
    const unresolvedPlugins = pluginsJson.map(async (plugin) => {
      setRemote(plugin.name, {
        ...commonRemoteConfig,
        url: plugin.entry,
      });

      const remoteModule = await getRemote(plugin.name, plugin.component);
      const remoteComponent = await unwrapModule(remoteModule);
      renderComponent(plugin.name, remoteComponent);
    });

    await Promise.all(unresolvedPlugins);
  } catch (e) {
    console.error(e);
  }
};

Available methods:

__federation_method_setRemote

Syntax

/**
 * Adds a new remote to the shared map of all remotes on the page.
 * @param {string} name - The name of the remote.
 * @param {IRemoteConfig} config - The configuration of the remote.
 */
function __federation_method_setRemote(name: string, config: IRemoteConfig): void;

Types

interface IRemoteConfig {
    url: (() => Promise<string>) | string; 
    format: "esm" | "systemjs" | "var";   
    from: "vite" | "webpack;
}

__federation_method_getRemote

Syntax

/**
 * Returns a component from a remote.
 * @param {string} remoteName - The name of the remote.
 * @param {string} componentName - The name of the component to retrieve.
 * @returns {Promise<unknown>} - The retrieved component.
 */
function __federation_method_getRemote(remoteName: string, componentName: string): Promise<unknown>;

__federation_method_unwrapDefault

Syntax

/**
 * Unwraps a module and returns its default export or the module itself.
 * @param {unknown} module - The module to unwrap.
 * @returns {unknown} - The default export or the module itself.
 */
function __federation_method_unwrapDefault(module: unknown): unknown;

__federation_method_wrapDefault

Syntax

/**
 * Checks for a default export and creates a wrapper if necessary.
 * @param {unknown} module - The module to process.
 * @param {boolean} need - A flag indicating whether to create a wrapper.
 * @returns {Promise<unknown>} - The wrapped module or the original.
 */
function __federation_method_wrapDefault(module: unknown, need: boolean): Promise<unknown>;

__federation_method_ensure

Syntax

/**
 * Checks if a module is initialized and initializes it if necessary.
 * @param {string} remoteName - The name of the remote.
 * @returns {Promise<unknown>} - The initialized remote.
 */
async function __federation_method_ensure(remoteName: string): Promise<unknown>;

Using `virtual:federation` with TypeScript

If you are using TypeScript, define the module types using declare module.

declare module example

To ensure correct functionality in the TypeScript environment, describe the module in a *.d.ts file:

declare module "virtual:__federation__" {
  interface IRemoteConfig {
    url: (() => Promise<string>) | string;
    format: "esm" | "systemjs" | "var";
    from: "vite" | "webpack";
  }

  export function __federation_method_setRemote(
    name: string,
    config: IRemoteConfig,
  ): void;

  export function __federation_method_getRemote(
    name: string,
    exposedPath: string,
  ): Promise<unknown>;

  export function __federation_method_unwrapDefault(
    unwrappedModule: unknown,
  ): Promise<unknown>;
  
  export function __federation_method_ensure(
    remoteName: string,
  ): Promise<unknown>;
  
  export function __federation_method_wrapDefault(
    module: unknown,
    need: boolean,
  ): Promise<unknown>;
}

Now you can load remote applications without predefining them in vite.config.

Example vue3-demo-esm

Add other example projects?

First of all, you need to determine whether the test is suitable for dev mode or build&serve mode, or both.

In addition, the current test will directly access localhost:5000 for testing, which means that the startup port of host must be 5000, otherwise it will directly lead to test failure.

How to set the test of `dev` mode or `build&serve` mode?

According to the file name of the test file.

For example, vue3-demo-esm.dev&serve.spec.ts means that tests will be built in dev mode and build&serve mode.

The vue3-demo-esm.dev.spec.ts will only build tests in dev mode, as summarized as follows

Mode	File Name
Only for `dev` mode	*.dev.spec.ts
Only for `build&serve` mode	*.serve.spec.ts
`dev` and `build&serve` mode	*.dev&serve.spec.ts

Testing in `Dev` mode

Since the current plug-in only supports the dev mode of vite on the host end, the dev mode test will execute the following code on the root path of the test project in turn.

pnpm run dev:host
pnpm run build:remotes
pnpm run serve:remotes
Execute test cases
pnpm run stop

This also means that there are at least four instructions in the package.json file of the project in dev mode.

  "scripts": {
    "build:remotes": "pnpm --filter \"./remote\"  build",
    "serve:remotes": "pnpm --filter \"./remote\"  serve",
    "dev:hosts": "pnpm --filter \"./host\" dev",
    "stop": "kill-port --port 5000,5001"
  },
  "workspaces": [
    "host",
    "remote"
  ]

Testing in `Build&Serve` mode

The build&serve mode will execute the following instructions in turn

pnpm run build
pnpm run serve
Execute test cases
pnpm run stop

This also means that there are at least three instructions in the package.json file of the project in build&serve mode.

  "scripts": {
    "build": "pnpm --parallel --filter \"./**\" build",
    "serve": "pnpm --parallel --filter \"./**\" serve ",
    "stop": "kill-port --port 5000,5001"
  },
  "workspaces": [
    "host",
    "remote"
  ]

FAQ

ERROR: `Top-level` await is not available in the configured target environment

The solution is to set build.target to esnext, which you can find at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/await to see the support for this feature in each browser.

build: {
    target: "esnext"
  }

 build: {
    target: ["chrome89", "edge89", "firefox89", "safari15"]
 }

Or you can try using the plugin vite-plugin-top-level-await to eliminate top-level-await, as demonstrated in vue3-demo- esm demonstrates this usage

Is not generating chunk properly?

Please check if you have started the project in dev mode with vite, currently only the fully pure host side can use dev mode, the remote side must use build mode to make the plugin take effect.

React uses federation for some questions

It is recommended to check this Issue, which contains most of the React related issues

The remote module failed to load the share of the local module, for example`localhost/:1 Uncaught (in promise) TypeError: Failed to fetch dynamically imported module: http://your url`

Reason: Vite has auto fetch logic for IP and Port when starting the service, no full fetch logic has been found in the Plugin, and in some cases a fetch failure may occur.

Solutions：

Explicitly declaring IP, Port, cacheDir in the local module ensures that our Plugin can correctly fetch and pass the dependent addresses.

Local module's vite.config.ts

export default defineConfig({
  server:{
    https: "http",
    host: "192.168.56.1",
    port: 5100,
  },
  cacheDir: "node_modules/.cacheDir",
}

error TS2307: Cannot find module

Add declarations in the d.ts file, like this

declare module "router-remote/*"{}

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Detailed design

English | 简体中文

vite-plugin-federation

A Vite/Rollup plugin which support Module Federation. Inspired by Webpack and compatible with Webpack Module Federation.

Navigation

Running results
Install
Usage
Example projects
Features
Configuration
Add other example projects?
Runtime add remotes with virtual:__federation__
FAQ
Star History
Wiki

Running results

Install

npm install @originjs/vite-plugin-federation --save-dev

yarn add @originjs/vite-plugin-federation --dev

Usage

Using the Module Federation usually requires more than 2 projects, one as the host side and one as the remote side.

Step 1: Configure the remote side.

for a vite project, modify vite.config.js:

// vite.config.js
import federation from "@originjs/vite-plugin-federation";
export default {
    plugins: [
        federation({
            name: 'remote-app',
            filename: 'remoteEntry.js',
            // Modules to expose
            exposes: {
                './Button': './src/Button.vue',
            },
            shared: ['vue']
        })
    ]
}

for a rollup project, modify rollup.config.js:

// rollup.config.js
import federation from '@originjs/vite-plugin-federation'
export default {
    input: 'src/index.js',
    plugins: [
        federation({
            name: 'remote-app',
            filename: 'remoteEntry.js',
            // Modules to expose
            exposes: {
                './Button': './src/button'.
            },
            shared: ['vue']
        })
    ]
}

Step 2: Configure the host side

for a vite project, modify vite.config.js:

// vite.config.js
import federation from "@originjs/vite-plugin-federation";
export default {
    plugins: [
        federation({
            name: 'host-app',
            remotes: {
                remote_app: "http://localhost:5001/assets/remoteEntry.js",
            },
            shared: ['vue']
        })
    ]
}

for a rollup project, modify rollup.config.js:

// rollup.config.js
import federation from '@originjs/vite-plugin-federation'
export default {
    input: 'src/index.js',
    plugins: [
        federation({
            name: 'host-app',
            remotes: {
                remote_app: "http://localhost:5001/remoteEntry.js",
            },
            shared: ['vue']
        })
    ]
}

Step 3: Using remote modules on the host side

Using a Vue project as an example

import { createApp, defineAsyncComponent } from "vue";
const app = createApp(Layout);
...
const RemoteButton = defineAsyncComponent(() => import("remote_app/Button"));
app.component("RemoteButton", RemoteButton);
app.mount("#root");

Using remote components in templates

<template>
    <div>
        <RemoteButton />
    </div>
</template>

Example projects

Examples	Host	Remote
basic-host-remote	`rollup`+`esm`	`rollup`+`esm`
react-in-vue	`vite`+`esm`	`vite`+`esm`
simple-react-esm	`rollup`+`esm`	`rollup`+`esm`
simple-react-systemjs	`rollup`+`systemjs`	`rollup`+`systemjs`
simple-react-webpack	`rollup`+`systemjs`	`webpack`+`systemjs`
vue2-demo	`vite`+`esm`	`vite`+`esm`
vue3-advanced-demo	`vite`+`esm` `vue-router`/`pinia`	`vite`+`esm` `vue-router`/`pinia`
vue3-demo-esm	`vite`+`esm`	`vite`+`esm`
vue3-demo-systemjs	`vite`+`systemjs`	`vite`+`systemjs`
vue3-demo-webpack-esm-esm	`vite/webpack`+`esm`	`vite/webpack`+`esm`
vue3-demo-webpack-esm-var	`vite`+`esm`	`webpack`+`var`
vue3-demo-webpack-systemjs	`vite`+`systemjs`	`webpack`+`systemjs`
react-vite	`vite`+`react`	`vite` + `react`

Features

Integration with Webpack

⚠️ Note:

Vite is relatively easy to use with the Webpack component, but Webpack is best used with the vite-plugin-federation component using the esm format, as the other formats lack complete test cases for now.
It is not recommended to mix Vite and Webpack in React projects, as there is no guarantee that Vite/Rollup and Webpack will generate the same chunk when packaging commonjs, which may cause problems with shared.

Vite Dev mode

As Vite is built on esbuild in dev development mode, we provide separate support for dev mode to take advantage of Vite's high performance development server in the case of remote module deployment.

⚠️ Note:

Only the Host side supports dev mode, the Remote side requires the RemoteEntry.js package to be generated using vite build. This is because Vite Dev mode is Bundleless and you can use vite build --watch to achieve a hot update effect.

Static import

// dynamic import
const myButton = defineAsyncComponent(() => import('remote/myButton'));
app.component('my-button' , myButton);
// or
export default {
  name: 'App',
  components: {
    myButton: () => import('remote/myButton'),
  }
}

// static import
import myButton from 'remote/myButton';
app.component('my-button' , myButton);
// or
export default {
  name: 'App',
  components: {
    myButton: myButton
  }
}

React

// dynamic import
const myButton = React.lazy(() => import('remote/myButton'))

// static import
import myButton from 'remote/myButton'

⚠️ Note:

Static imports may rely on the browser Top-level await feature, so you will need to set build.target in the configuration file to next or use the plugin vite-plugin-top-level-await. You can see the browser compatibility of top-level await here compatibility)

Configuration

`name: string`

Required as the module name of the remote module.

`filename:string`

As the entry file of the remote module, not required, default is remoteEntry.js

`transformFileTypes:string[]`

In most cases, the file types that the plug-in needs to process do not need to be configured, because these types are set by default.['.js', '.ts', '.jsx', '.tsx', '.mjs', '.cjs', '.vue', '.svelte'],When you customize some file types and need the vite-plugin-federation plugin processing, please add it to the array configuration.

`exposes`

As the remote module, the list of components exposed to the public, required for the remote module.

exposes: {
// 'externally exposed component name': 'externally exposed component address'
    './remote-simple-button': './src/components/Button.vue', 
    './remote-simple-section': './src/components/Section.vue'
},

If you need a more complex configuration

exposes: {
    './remote-simple-button': {
        import: './src/components/Button.vue',
        name: 'customChunkName',
        dontAppendStylesToHead: true
    },
},

The import property is the address of the module. If you need to specify a custom chunk name for the module use the name property.

const styleContainer = document.createElement("div");
const hrefs = window["css__App__./remote-simple-button"];

hrefs.forEach((href: string) => {
    const link = document.createElement('link')
    link.href = href
    link.rel = 'stylesheet'
    styleContainer.appendChild(link);
});

`remotes`

The remote module entry file referenced as a local module

`external:string|Promise<string>`

remote module address, e.g. https://localhost:5011/remoteEntry.js
You can simply configure it as follows

  remotes: {
    // 'remote module name': 'remote module entry file address'
    'remote-simple': 'http://localhost:5011/remoteEntry.js',
}

Or do a slightly more complex configuration, if you need to use other fields

remotes: {
    remote-simple: {
        external: 'http://localhost:5011/remoteEntry.js',
        format: 'var',
    }
}

`externalType: 'url'|'promise'`

default: 'url'
Set the type of external. If you want to use a dynamic url address, you can set the external as promise, but please note that you need to set the externalType as 'promise' at the same time, and please ensure that the code of the promise part is correct, otherwise the package may fail,here is a simple example.

remotes: {
      home: {
          external: `Promise.resolve('your url')`,
          externalType: 'promise'
      },
},
    
// or from networke
remotes: {
    remote-simple: {
        external: `fetch('your url').then(response=>response.json()).then(data=>data.url)`,
        externalType: 'promise'
    }
}

`format:'esm'|'systemjs'|'var'`

default:'esm'
Specify the format of the remote component, this is more effective when the host and the remote use different packaging formats, for example the host uses vite + esm and the remote uses webpack + var, in which case you need to specify type : 'var'

`from` : `'vite'|'webpack'`

default : 'vite'
Specify the source of the remote component, from vite-plugin-federation select vite, from webpack select webpack

`shared`

`import: boolean`

default: true
The default is true, whether to add shared to the module, only for the remote side, remote will reduce some of the packaging time when this configuration is turned on, because there is no need to package some of the shared, but once there is no shared module available on the host side, it will report an error directly, because there is no fallback module available

`shareScope: string`

default: 'default'
Default is default, the shared domain name, just keep the remote and host sides the same

`version: string`

`requiredVersion: string`

`packagePath: string`

supportMode: only serve
Allow custom packages to be shared via packagePath (previously limited to those under node_modules), For Example You can only define similar shared

shared :{
    packageName:{
        ...
    }
}

packageName must be a package under node_modules, such as vue, react, etc., but you cannot define your own package. But now you can share a custom package by specifying the package path, for example

shared: {
    packageName: {
        packagePath: './src/a/index.js'
    }
}

`generate : boolean`

default: true
generate a shared chunk file or not , if you make sure that the host side has a share that can be used, then you can set not to generate a shared file on the remote side to reduce the size of the remote's chunk file, which is only effective on the remote side, the host side will generate a shared chunk no matter what.

shared: {
    packageName: {
        generate: false
    }
}

`modulePreload : boolean`

default: false
if true, the shared dependency bundle file append to html head as link modulepreload, only work in prod mode.

shared: {
    packageName: {
        modulePreload: true
    }
}

Runtime add remotes with `virtual:federation`

Note: This is a virtual module, for a deeper understanding of virtual modules in Vite, see: https://vite.dev/guide/api-plugin#virtual-modules-convention

API `virtual:federation`

Using methods from the virtual:__federation__ module, you can implement dynamic loading of a remote application.

import {
  __federation_method_getRemote as getRemote,
  __federation_method_setRemote as setRemote,
  __federation_method_unwrapDefault as unwrapModule,
  type IRemoteConfig,
} from "virtual:__federation__";

const renderComponent = () => {
  throw Error("Not implemented");
}

const loadCrmPlugins = async () => {
  try {
    const pluginsResponse = await fetch("some-backed.com/plugins");
    const pluginsJson = await pluginsResponse.json();
    
    const unresolvedPlugins = pluginsJson.map(async (plugin) => {
      setRemote(plugin.name, {
        ...commonRemoteConfig,
        url: plugin.entry,
      });

      const remoteModule = await getRemote(plugin.name, plugin.component);
      const remoteComponent = await unwrapModule(remoteModule);
      renderComponent(plugin.name, remoteComponent);
    });

    await Promise.all(unresolvedPlugins);
  } catch (e) {
    console.error(e);
  }
};

Available methods:

__federation_method_setRemote

Syntax

/**
 * Adds a new remote to the shared map of all remotes on the page.
 * @param {string} name - The name of the remote.
 * @param {IRemoteConfig} config - The configuration of the remote.
 */
function __federation_method_setRemote(name: string, config: IRemoteConfig): void;

Types

interface IRemoteConfig {
    url: (() => Promise<string>) | string; 
    format: "esm" | "systemjs" | "var";   
    from: "vite" | "webpack;
}

__federation_method_getRemote

Syntax

/**
 * Returns a component from a remote.
 * @param {string} remoteName - The name of the remote.
 * @param {string} componentName - The name of the component to retrieve.
 * @returns {Promise<unknown>} - The retrieved component.
 */
function __federation_method_getRemote(remoteName: string, componentName: string): Promise<unknown>;

__federation_method_unwrapDefault

Syntax

/**
 * Unwraps a module and returns its default export or the module itself.
 * @param {unknown} module - The module to unwrap.
 * @returns {unknown} - The default export or the module itself.
 */
function __federation_method_unwrapDefault(module: unknown): unknown;

__federation_method_wrapDefault

Syntax

/**
 * Checks for a default export and creates a wrapper if necessary.
 * @param {unknown} module - The module to process.
 * @param {boolean} need - A flag indicating whether to create a wrapper.
 * @returns {Promise<unknown>} - The wrapped module or the original.
 */
function __federation_method_wrapDefault(module: unknown, need: boolean): Promise<unknown>;

__federation_method_ensure

Syntax

/**
 * Checks if a module is initialized and initializes it if necessary.
 * @param {string} remoteName - The name of the remote.
 * @returns {Promise<unknown>} - The initialized remote.
 */
async function __federation_method_ensure(remoteName: string): Promise<unknown>;

Using `virtual:federation` with TypeScript

If you are using TypeScript, define the module types using declare module.

declare module example

To ensure correct functionality in the TypeScript environment, describe the module in a *.d.ts file:

declare module "virtual:__federation__" {
  interface IRemoteConfig {
    url: (() => Promise<string>) | string;
    format: "esm" | "systemjs" | "var";
    from: "vite" | "webpack";
  }

  export function __federation_method_setRemote(
    name: string,
    config: IRemoteConfig,
  ): void;

  export function __federation_method_getRemote(
    name: string,
    exposedPath: string,
  ): Promise<unknown>;

  export function __federation_method_unwrapDefault(
    unwrappedModule: unknown,
  ): Promise<unknown>;
  
  export function __federation_method_ensure(
    remoteName: string,
  ): Promise<unknown>;
  
  export function __federation_method_wrapDefault(
    module: unknown,
    need: boolean,
  ): Promise<unknown>;
}

Now you can load remote applications without predefining them in vite.config.

Example vue3-demo-esm

Add other example projects?

First of all, you need to determine whether the test is suitable for dev mode or build&serve mode, or both.

In addition, the current test will directly access localhost:5000 for testing, which means that the startup port of host must be 5000, otherwise it will directly lead to test failure.

How to set the test of `dev` mode or `build&serve` mode?

According to the file name of the test file.

For example, vue3-demo-esm.dev&serve.spec.ts means that tests will be built in dev mode and build&serve mode.

The vue3-demo-esm.dev.spec.ts will only build tests in dev mode, as summarized as follows

Mode	File Name
Only for `dev` mode	*.dev.spec.ts
Only for `build&serve` mode	*.serve.spec.ts
`dev` and `build&serve` mode	*.dev&serve.spec.ts

Testing in `Dev` mode

Since the current plug-in only supports the dev mode of vite on the host end, the dev mode test will execute the following code on the root path of the test project in turn.

pnpm run dev:host
pnpm run build:remotes
pnpm run serve:remotes
Execute test cases
pnpm run stop

This also means that there are at least four instructions in the package.json file of the project in dev mode.

  "scripts": {
    "build:remotes": "pnpm --filter \"./remote\"  build",
    "serve:remotes": "pnpm --filter \"./remote\"  serve",
    "dev:hosts": "pnpm --filter \"./host\" dev",
    "stop": "kill-port --port 5000,5001"
  },
  "workspaces": [
    "host",
    "remote"
  ]

Testing in `Build&Serve` mode

The build&serve mode will execute the following instructions in turn

pnpm run build
pnpm run serve
Execute test cases
pnpm run stop

This also means that there are at least three instructions in the package.json file of the project in build&serve mode.

  "scripts": {
    "build": "pnpm --parallel --filter \"./**\" build",
    "serve": "pnpm --parallel --filter \"./**\" serve ",
    "stop": "kill-port --port 5000,5001"
  },
  "workspaces": [
    "host",
    "remote"
  ]

FAQ

ERROR: `Top-level` await is not available in the configured target environment

build: {
    target: "esnext"
  }

 build: {
    target: ["chrome89", "edge89", "firefox89", "safari15"]
 }

Or you can try using the plugin vite-plugin-top-level-await to eliminate top-level-await, as demonstrated in vue3-demo- esm demonstrates this usage

Is not generating chunk properly?

React uses federation for some questions

It is recommended to check this Issue, which contains most of the React related issues

The remote module failed to load the share of the local module, for example`localhost/:1 Uncaught (in promise) TypeError: Failed to fetch dynamically imported module: http://your url`

Reason: Vite has auto fetch logic for IP and Port when starting the service, no full fetch logic has been found in the Plugin, and in some cases a fetch failure may occur.

Solutions：

Explicitly declaring IP, Port, cacheDir in the local module ensures that our Plugin can correctly fetch and pass the dependent addresses.

Local module's vite.config.ts

export default defineConfig({
  server:{
    https: "http",
    host: "192.168.56.1",
    port: 5100,
  },
  cacheDir: "node_modules/.cacheDir",
}

error TS2307: Cannot find module

Add declarations in the d.ts file, like this

declare module "router-remote/*"{}

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