Microfrontends with React

Author: Stephen Grider udemy

Code lives here

Section 1: The Basics of Microfrontends

What are micro frontends?

  • Divide a monolithic app into multiple, smaller apps
  • Each smaller app is responsible for a distinct feature of the product

Why use them?

  • Multiple engineering teams can work on isolation;
  • Each smaller app is easier to understand and make changes to;

Ideally, a MFE should not talk between each other, but with some sort of backend API

Sample Application

Types of integration

  • Build-Time integration (compile-time integration): Before the container gets loaded in the browser, it gets access to ProductsList source code;
    • Pros: Easy to setup and understand
    • Cons: Container has to be re-deployed every time ProductsList has updated and tempting to tightly couple Container + ProductsList together;


  • Run-Time integration (client-side integration): After the container gets loaded in the browser, it gets access to ProductsList source code;

    • Pros: ProductsList can be deployed independently at any time and can deploy different versions of ProductsList, and Container can decide which one to use
    • Cons: tooling + setup is far more complicated
    • Example of this integration is Webpack Module Federation
      • most flexible and performant solution around right now
    • Run-Time
  • Server Integration: while sending down JS to load up Container, a server decides on whether or not to include ProductsList source

Webpack combines many js files (from project and dependencies) into one single file.

Section 2: The Basics of Module Federation



Host: Container, Remote: Products

What module federation does on products project?

Federation Products

What module federation does on container project?

Federation Container

What is the flow of execution?

Federation Flow

Configuration options


Container configuration


Products configuration

The Development Process


index.html of Products and cart are only used during developments of subprojects.

index.html of Container is used during development + production

Section 3: Sharing Dependencies Between Apps

Using Shared Modules

Both cart and products modules both have faker as a dependency. The bad part is that we are loading in twice. (check vendors-node_modules_faker)


Container should load just one and provide a copy for it. How?

Add to both cart and products webpack.config.js:

new ModuleFederationPlugin({
      name: "products",
      filename: "remoteEntry.js",
      shared: ["faker"], <=========
      exposes: {
        "./ProductsIndex": "./src/index",

And then, we just have one faker loaded:


Async Script Loading

After this, we need to add async script loading to our services. If we got this error message:


We should do this change on our apps:

Move the code to another file, and load it on index like this:


This step introduces some asynchronicity for loading js code and gives room to webpack the opportunity to figure out which file needs to run successfully.

Asynd loading respects versioning of our apps. Two different versions makes two lib loadings. You can declare your libs as singleton in order to guarantee that is just a single version of the same app:

new ModuleFederationPlugin({
      name: "products",
      filename: "remoteEntry.js",
      shared: {
        faker: {
          singleton: true,
      exposes: {
        "./ProductsIndex": "./src/index",

How to run my code in isolation (microfront end dev) and production? An example:


import faker from "faker";

const mount = (el) => {
  const cartText = `<div> You have ${faker.random.number()} items in your cart</div>`;
  el.innerHTML = cartText;
  //ReactDOM.render(<App />, el) <- if it's react

//development mode of products microfrontend
if (process.env.NODE_ENV === "development") {
  const devDiv = document.getElementById("dev-cart");
  if (devDiv) {

export { mount };

On container app:

import { mount as mountProduct } from "products/ProductsIndex";
import { mount as mountCart } from "cart/CartShow";


Section 4: Linking Multiple Apps Together

inflx. requid1 : no shared state: redux, no reducer, rno context, nothing like that between child projects

inflexible 3 css should be scoped

Section 5: Generic Ties Between Projects

Section 6: Implementing a CI/CD Pipeline

deployment slide (48)

next is about step 2 (location of child)

at buld time , webpack/we need to know where the remote file is located

remoteEntry file is fixed related to location of child app (At present == web pack module federation plugin, there is work being done to dynamic name)

55 silde

Section 7: Deployment to Amazon Web Services

62 script tag of main doesn’t have the tag, uses cloud front url need to put it the /contianer/latest should use 63 webpal public path

Microfront ends behave != in dev and producton

Section 8: Microfrontend-Specific AWS Config

64 still doesn’t work because see setp on github actions, this is important for index but also create invalidation for each invalidation remoteEntry.js

Why so much js files? all separated dependencies package json file and try to include those as separade included JS files (to load it just once) if you want one big bundle, remove shared

optional, production style workflow

Section 9: Handling CSS in Microfrontends

Scope CSS solutions slide

bugs when use same css-in-js of material ui library between !=- projects (colision, aula 76)) (problem with conflicts of class name generation)

Section 10: Implementing Multi-Tier Navigation’

80 Navigation requirements infx requirement 1 and 2 and 3 and 4 (Screen Shot 2021-03-06 at 10.03.01 AM.png) 5 and 6

81 Summary

82 Overview routing libraies

why browser on cintainer and memory on childs? ony container use browser address bar, to avoid race conditions

83, communication between services

Section 11: Performance Considerations

Screen Shot 2021-03-06 at 11.30.58 AM.png

public path issue (remote entry screen shot)

98, we need to reate a entry point for memory history

99. Lazily Loading SubApps

Lazy load of microfront ends with module federation

lazy, Suspense const MarketingLazy = lazy(() => import(“./components/MarketingApp”));

<Suspense fallback={<div>loading…</div>}> <Route path="/auth" component={AuthLazy} /> <Route path="/" component={MarketingLazy} /> </Suspense>

Section 12: Authentication in Microfrontends

Section 13: Using Other Frontend Frameworks





Demo with two micro-front ends consuming bpmn/dmn editors, loading the lib only and with bpmn/dmn microfrontend hosted on github. (remember to take a look on Tiago’s sample)

Next, DashBuilder runtimes being consumed as a microfront end

what are the cons of federated modules

TODO: replace aws CLI action

? Does pf4 react does css-in-js?

Index _