Compute `ModuleFederationPlugin`s remotes' URLs in the runtime

With the remotes property we define where to pull remotes from:

remotes: {
  widget: `widget@http://localhost:3001/remoteEntry.js`,
},

It is possible to alternate the URL during the build

remotes: {
  widget: `widget@${isDev ? 'http://localhost:3001' : '/apps/widgets'}/remoteEntry.js`,
},

Though it seems like there is no way to define the remote’s URL dynamically in runtime.

I would imagine it like this:

remotes: {
  widget: () => {
    const prefix = location.host.startsWith('eu.') ? 'europe' : 'us';
    return `widget@${prefix}/apps/widgets/remoteEntry.js`
  },
},

It would be really useful to have such an option.

_Originally posted by @jazzfog in https://github.com/webpack/webpack/discussions/12213_

[jazzfog]

Still think it’d be a useful feature.

[vankop]

remotes basically are external modules, you can use promise external see webpack test case for that https://github.com/webpack/webpack/blob/main/test/configCases/container/circular/webpack.config.js

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so for dynamic externals please use promise