About

Library is a set of webpack plugins which gives support of Module Federation into NodeJS.

Usage example with NextJS https://github.com/telenko/node-mf-example

Here is also my article about this library.

Purpose of creating

Release of Webpack Module Federation really have made a shift in modern architecture of web applications. But what about NodeJS and such frameworks like Next? What about SSR? I see for now a gap in webpack, so pure ModuleFederation plugin can not be used inside NodeJS environment. Muliple examples of NextJS+MF here https://github.com/module-federation/module-federation-examples with NextJS using only client-side rendering or not using remote deployed build at all.

What can I propose

I have implemented 2 plugins for webpack:

1. NodeAsyncHttpRuntime - Plugin which should be used on a remote side to build remote scripts for NodeJS. But the main key of plugin is resolution of modules - it is done via http requests, so NodeJS can dynamically resolve child modules, load them and perform.
2. NodeModuleFederation - Plugin is wrapper around origin WebpackModuleFederation plugin and adds NodeJS specific resolution of remote modules (same thing: resolution is done via http requests)

Getting started

1) On remote library:

1.1) Install package (remote can be either pure JS application or NodeJS application - doesn't matter) npm i --save-dev @telenko/node-mf

1.2. Customize webpack configuration, so it should now build 2 targets: for web (if you want legacy browser build) and for node (webpack for now doesn't support universal targets)

1.3) For node build add NodeAsyncHttpRuntime plugin and set webpack's 'target' flag to false

    //pseudocode
    module.exports = [
        {
            target: "web",
            ...webOptionsWebpack
        },
        {
            target: false,
            plugins: [
                new NodeAsyncHttpRuntime() //this is instead of target to make it work
            ],
            ...nodeOptionsWebpack
        }
    ];

1.4) Serve both builds

Full example is here https://github.com/telenko/node-mf-example/blob/master/remoteLib/webpack.config.js

2) On NodeJS application:

2.1) Install library npm i --save-dev @telenko/node-mf

2.2) Add NodeModuleFederation plugin to the webpack config (api parameters schema is same) !Note, remote script url should point to 'node' build (which should be built with NodeAsyncHttpRuntime)

  module.exports = {
      plugins: [
          new NodeModuleFederation({
              remotes: {
                  someLib: "someLib@http://some-url/remoteEntry.node.js"
              },
              shared: {
                  lodash: {
                      eager: true,
                      singleton: true,
                      requiredVersion: "1.1.2"
                  }
              }
          })
      ],
      ...otherWebpackOptions
  };

Full example of setuping NextJS with SSR here https://github.com/telenko/node-mf-example/blob/master/host/next.config.js

Risks

Aren't 2 build makes build-time 2 times longer?

Yes, if we speak about NextJS and SSR - we need both builds: for web and for node, and we have to start entire build separately without sharing built chunks. That will increase build time 2 times.

Security

Since NodeJS out of the box doesn't support remote scripts execution (like in browser we can add script tag) it looks like a hack calling http request then 'eval'-ing it. I'm not sure if it is safe to add remote script execution on server side, but it is the only one possible way to make it on server.

Roadmap

1. https support
2. Next.js support for NodeAsyncHttpRuntime plugin