Backend for frontend security architecture (BFF) using Vue.JS and ASP.NET Core

Implements an OpenID Connect confidential client client using Vue.JS and a UI and ASP.NET Core to implement the API. The application is secured using an OpenID Connect confidential client using OAuth PKCE. The Vue.js application is served from the ASP.NET Core application using the YARP reverse proxy in development. The Vue.js application is built into the wwwroot of the ASP.NET Core application in production. OpenIddict is used to implement the identity server.

Setup Server

The ASP.NET Core project is setup to run in development and production. In production, it uses the Vue.js production build deployed to the wwwroot. In development, it uses MS YARP reverse proxy to forward requests.

Important

In production, the Vue.js project is built into the wwwroot of the .NET project.

Configure the YARP reverse proxy to match the Vue.js URL. This is only required in development. I always use HTTPS in development and the port needs to match the Vue.js developement env (vite.config.js).

 "UiDevServerUrl": "https://localhost:4202",
  "ReverseProxy": {
    "Routes": {
      "route1": {
        "ClusterId": "cluster1",
        "Match": {
          "Path": "{**catch-all}"
        }
      }
    },
    "Clusters": {
      "cluster1": {
        "HttpClient": {
          "SslProtocols": [
            "Tls12"
          ]
        },
        "Destinations": {
          "cluster1/destination1": {
            "Address": "https://localhost:4202/"
          }
        }
      }
    }
  }

Setup Vue.js Vite project

Add the certificates to the nx project for example in the /certs folder

Update the vite.config.ts file:

import { defineConfig } from 'vite'
import vue from '@vitejs/plugin-vue'
import fs from 'fs';

// https://vitejs.dev/config/
export default defineConfig({
  plugins: [vue()],
  server: {
    https: {
      key: fs.readFileSync('./certs/dev_localhost.key'),
      cert: fs.readFileSync('./certs/dev_localhost.pem'),
	},
    port: 4202,
    strictPort: true, // exit if port is in use
    hmr: {
      clientPort: 4202, // point vite websocket connection to vite directly, circumventing .net proxy
    },
  },
  optimizeDeps: {
    force: true,
  },
  build: {
    outDir: "../server/wwwroot",
    emptyOutDir: true
  },
})

Note

The ASP.NET Core project setup uses port 4202, this needs to match the YARP reverse proxy settings for development.

Setup development

The development environment is setup to use the default tools for each of the tech stacks. Vue.js is used like recommended. I use Visual Studio code. A YARP reverse proxy is used to integrate the Vue.js development into the backend application.

Note

Always run in HTTPS, both in development and production

npm start

The OpenID Connect client is setup using the default ASP.NET Core OpenID connect handler.

services.AddAuthentication(options =>
{
    options.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
    options.DefaultChallengeScheme = OpenIdConnectDefaults.AuthenticationScheme;
})
.AddCookie()
.AddOpenIdConnect(options =>
{
    builder.Configuration.GetSection("OpenIDConnectSettings").Bind(options);
    options.Authority = builder.Configuration["OpenIDConnectSettings:Authority"];
    options.ClientId = builder.Configuration["OpenIDConnectSettings:ClientId"];
    options.ClientSecret = builder.Configuration["OpenIDConnectSettings:ClientSecret"];

    options.SignInScheme = CookieAuthenticationDefaults.AuthenticationScheme;
    options.ResponseType = OpenIdConnectResponseType.Code;

    options.SaveTokens = true;
    options.GetClaimsFromUserInfoEndpoint = true;
    options.TokenValidationParameters = new TokenValidationParameters
    {
        NameClaimType = "name"
    };
});

services.AddControllersWithViews(options =>
    options.Filters.Add(new AutoValidateAntiforgeryTokenAttribute()));

services.AddRazorPages().AddMvcOptions(options =>
{
    var policy = new AuthorizationPolicyBuilder()
        .RequireAuthenticatedUser()
        .Build();
    options.Filters.Add(new AuthorizeFilter(policy));
});

Add the Azure App registration settings to the appsettings.Development.json and the ClientSecret to the user secrets.

"OpenIDConnectSettings": {
    "Authority": "https://localhost:44318",
    "ClientId": "oidc-pkce-confidential",
    "ClientSecret": "oidc-pkce-confidential_secret"
},

Debugging

Start the Vue.js project from the ui folder

npm start

Start the ASP.NET Core project from the server folder

dotnet run

Or just open Visual Studio and run the solution.

Github actions build

Github actions is used for the DevOps. The build pipeline builds both the .NET project and the Vue.js project using npm. The two projects are built in the same step because the UI project is built into the wwwroot of the server project.

name: .NET and npm build

on:
  push:
    branches: [ "main" ]
  pull_request:
    branches: [ "main" ]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:

      - uses: actions/checkout@v4
      - name: Setup .NET
        uses: actions/setup-dotnet@v4
        with:
          dotnet-version: 9.0.x

      - name: Restore dependencies
        run: dotnet restore

      - name: npm setup
        working-directory: ui
        run: npm install

      - name: ui-build
        working-directory: ui
        run: npm run build

      - name: Build
        run: dotnet build --no-restore
      - name: Test
        run: dotnet test --no-build --verbosity normal

Credits and used libraries

• NetEscapades.AspNetCore.SecurityHeaders
• Yarp.ReverseProxy
• Microsoft.Identity.Web
• ASP.NET Core
• Vue.js
• Vite
• OpenIddict

Links

https://vuejs.org/

https://vitejs.dev/

https://github.com/vuejs/create-vue

https://documentation.openiddict.com/

https://www.koderhq.com/tutorial/vue/vite/

https://github.com/damienbod/bff-aspnetcore-angular

https://github.com/damienbod/bff-openiddict-aspnetcore-angular

https://github.com/damienbod/bff-aspnetcore-vuejs