Micro Frontend in Angular: Using Module Federation

In this post, we will implement Micro-Frontends in Angular using Webpack 5 Module Federation.

Credit: This post is based on this article written by Manfred Steyer

May-12-2021 Update: Added Dockerfiles for both the projects. Please check the Running the applications section.

Table Of Contents

• Pre-Requisites
• Create Host Application
• Create Microfrontend Application with feature module
• Add Module Federation
• Webpack Config changes
• Route changes in Host
• Running the applications
• Conclusion

Pre-Requisites:

1. Angular CLI: 11.2.8
2. Node: 15.4.0
3. Yarn: 1.22.10

We will be using yarn as package manager instead of NPM. Why? We will be using Webpack 5 Module Federation with Angular 11. Angular CLI 11 uses webpack version 4. We will be overriding the webpack version in package.json and yarn is required to override the web pack version for angular cli.

Create Host Application

Step 1: Set Yarn as package manager

ng config cli.packageManager yarn 

Any ng add or ng update command will yarn instead of rpm to install the packages.

Step 2: Create a workspace

ng new angular-mfe-example --createApplication="false" 

The above command will create a workspace with no projects.

Step 3: Create host (Shell) app

ng g applicatie host --routing --style=css 

Step 4: Create home component

ng g c home --project=host

Step 5: Update Route to add path to Home and change AppComponent

Add Route to app-routing.module.ts

Clean up app.component.html

Step 6: Run the application

ng serve host

Run the host app. It should run in default port 4200

Create Microfrontend Application with feature module

We will now create another application under the same workspace. The steps to create it are the same as above.

Step 1: Create mfe1 application and home component

ng g application mfe1 --routing --style=css

ng g c home --project=mfe1

mfe1 project will get created under the main workspace

Step 2: Create a new feature module under mfe1

Create a new feature module mfefeature and a component under the feature module

ng g m mfefeature --routing --project=mfe1

ng g c mfefeature --project=mfe1

Add the route to the mfefeature component in the mfefeature-routing.module.ts

Step 3: Change App routing
Update routing module to add path to home component under mfe1.

Update routing module to add path to mfe1. The mfefeature module is lazy loaded

{
    path: 'mfe1',
    loadChildren: () => 
      import("./mfefeature/mfefeature.module").then((m) => m.MfefeatureModule),
  },

Please ensure that home component is pointing to the one under mfe1 project and not host.

Step 4: Change HomeComponent

Change home.component.html

Step 5: Change AppComponent in mfe1

Change app.component.html to include links to home and mfe1

Step 6: Run the application

ng serve mfe1

Run the mfe1 app. It should run in default port 4200.

At the end of this step, we have created 2 applications in the same workspace. The mfe1 application has a feature module. This feature module will be loaded as Microfrontend in the host application in the subsequent sections.

Add Module Federation

Angular CLI does not expose the webpack to us. We need to install custom builder to enable module federation.

Add @angular-architects/module-federation package to both the projects.

ng add @angular-architects/module-federation --project host --port 4200

ng add @angular-architects/module-federation --project mfe1 --port 5000

The above command creates web pack config files and updates angular.json.

Webpack Config changes

Step 1: Add Webpack5 to the workspace

We will now add webpack5 to the workspace. Add the below entry to package.json

"resolutions": {
    "webpack": "^5.4.0",
    "license-webpack-plugin": "2.3.17"
  },

We need to add license-webpack-plugin@2.3.17 as Angular11 uses 2.3.11 version which gives an error when used with webpack5.

Step 2: Add Modulefederated plugin to mfe1

Locate webpack.config.js under mfe1 project and uncomment the config values under // For remotes (please adjust)

Make the following changes

name: "mfe1",
filename: "mfe1remoteEntry.js",
exposes: {
    './MfefeatureModule': './projects/mfe1/src/app/mfefeature/mfefeature.module.ts',
        },  

We are exposing mfefeature.module under the name MfefeatureModule. This name will be used when we are lazy loading this module in host's app-routing.module.ts
The feature module will be available in mfe1remoteEntry.js

Step 3: Add Modulefederated plugin to host

Locate webpack.config.js under host project and uncomment the lines under // For hosts (please adjust)

Make the following changes

remotes: {
     "mfe1": "mfe1@http://localhost:5000/mfe1remoteEntry.js",
},

We are mapping the name 'mfe1' to the path where the remote can be found. Please note that the mfe1 project needs to run in port 5000 and we are pointing to mfe1remoteentry.js which is the name we gave in the mfe1's webpack.config.js

Route changes in Host

Step 1: Add route to mfe1 feature module

Add path to mfe1 and lazy load the mfe feature module

In host's app-routing.module.ts

{
    path: 'mfe1',
    loadChildren: () =>
      import('mfe1/MfefeatureModule').then((m) => {
        return m.MfefeatureModule;
      }),
  }

Note that in the import statement we are using MfeFeatureModule, which is the name of the module we gave in mfe1's webpack.config.js

Step 2: Declare MfeFeatureModule

The path mfe1/MfeFeatureModule mentioned in the import statement does not "exist" within host project. When we compile the host project it will throw an error.

To fix the error, we will create decl.d.ts under host and declare the module

declare module 'mfe1/MfefeatureModule'

Step 3: Add route for mfe in Appcomponent

In app.component.html, make the following changes

<h1>Angular MFE Host</h1>
<a routerLink='/'>Main</a> &#160;
<a routerLink='/mfe1'>Link to MFE</a>
<router-outlet></router-outlet>

Running the applications

Option 1: Run in terminal

Open 2 command terminals

In terminal 1 run

ng serve host

In terminal 2 run

ng serve mfe1

Open localhost:4200

you will able to navigate to the mfe1 which is actually running in localhost:5000

Option 2: Dockerize the apps and run in containers

*Step 1: * Create nginx default configuration file

Under the main folder create a folder nginx.

Inside this folder create a file "default.conf" and copy the below commands

server {

  listen 80;

  sendfile on;

  default_type application/octet-stream;


  gzip on;
  gzip_http_version 1.1;
  gzip_disable      "MSIE [1-6]\.";
  gzip_min_length   1100;
  gzip_vary         on;
  gzip_proxied      expired no-cache no-store private auth;
  gzip_types        text/plain text/css application/json application/javascript application/x-javascript text/xml application/xml application/xml+rss text/javascript;
  gzip_comp_level   9;


  root /usr/share/nginx/html;


  location / {
    try_files $uri $uri/ /index.html =404;
  }

}

This configuration is copied during the creation of the docker image.

*Step 2: * Create Dockerfile for host
In the main folder create HostDockerfile. This is in the same level as projects folder.

FROM node:15-alpine as builder

COPY package.json  ./

RUN yarn install 

RUN mkdir /ng-app

RUN mv ./node_modules ./ng-app

WORKDIR /ng-app

COPY . .

RUN npm run ng build --prod --project=host

FROM nginx
COPY nginx/default.conf /etc/nginx/conf.d/default.conf
COPY --from=builder /ng-app/dist/host /usr/share/nginx/html

CMD ["nginx", "-g", "daemon off;"]

Step 3: Create Docker image for host using the below command

docker build -t host -f .\HostDockerfile

The name of the docker image is host. Please note that the name of the dockerfile is "HostDockerfile".

Step 4: Create Dockerfile for mfe1
In the main folder create MfeDockerfile. This is in the same level as projects folder.

FROM node:15-alpine as builder

COPY package.json  ./

RUN yarn install 

RUN mkdir /mfe-app

RUN mv ./node_modules ./mfe-app

WORKDIR /mfe-app

COPY . .

RUN npm run ng build --prod --project=mfe1

FROM nginx
COPY nginx/default.conf /etc/nginx/conf.d/default.conf
COPY --from=builder /mfe-app/dist/mfe1 /usr/share/nginx/html

CMD ["nginx", "-g", "daemon off;"]

Step 5: Create Docker image for mfe1 using the below command

docker build -t mfe1 -f .\MfeDockerfile

The name of the docker image is mfe1. Please note that the name of the dockerfile is "MfeDockerfile".

Step 6: Create containers for host and mfe1

Run the below commands to create and run the containers

docker run -d -p 4200:80 host

docker run -d -p 5000:80 mfe1

The host expects mfe1 to run in port 5000, hence running the mfe1 container in port 5000.

Conclusion

This is a simple tutorial that demonstrates implementation of Microfrontend using Webpack Module Federation.

You can refer to my GitHub repo for the completed solution.