Micro frontends combination: Webpack host and Rspack remote

[nurbolnygmanov]

@hardfist
I was wondering in case of gradual migrating micro frontends from webpack to rspack is it possible to combine host app that is bundled by webpack and remotes by rspack? How is compatibility and what are the plans for this compatibility?

[mg1986jp]

Yes, this works. Rspack's Module Federation implementation is wire-compatible with Webpack 5's Module Federation — they both produce the same container protocol at runtime. So a Webpack host can consume Rspack remotes and vice versa.

A few things to keep in mind:

1. Use the same MF plugin version. If you're using @module-federation/enhanced (the updated plugin), use it in both the host and remotes. If the host is on Webpack's built-in ModuleFederationPlugin, the Rspack remote should use rspack.container.ModuleFederationPlugin (the built-in one). Mixing @module-federation/enhanced on one side and the built-in plugin on the other can cause version negotiation issues.

2. Shared dependencies versions must align. React, React DOM, etc. need compatible version ranges on both sides. This is the same constraint you'd have with Webpack-only MF, but worth double-checking since different bundlers might resolve slightly different versions.

3. publicPath needs to be set correctly on the Rspack remote — auto works in most cases.

4. Build output format should match. If the host expects var library type (the default), the remote should also use var. Don't mix module and var.

The Rspack team has explicitly maintained this compatibility as a design goal, so there shouldn't be any protocol-level issues. If you hit problems they're likely configuration mismatches rather than fundamental incompatibilities.

Are you using @module-federation/enhanced or the built-in plugins?