How to implement serverless authentication with Azure Active Directory in a Nest.js application

Implementing serverless authentication with Azure Active Directory (Azure AD) in a Nest.js application involves several steps. We'll use Azure Functions for the serverless aspect and Azure AD for authentication. Here's a high-level overview of the process:

1. Set up Azure Active Directory:

   • Create an Azure AD application in the Azure portal.
   • Configure the application's authentication settings, such as redirect URIs and permissions.

2. Set up Azure Functions:

   • Create an Azure Functions application in the Azure portal.
   • Configure the application settings, such as runtime stack and region.

3. Implement authentication logic:

   • Create an Azure Function that handles authentication.
   • Use the @azure/identity package to obtain access tokens from Azure AD.
   • Secure the Azure Function with Azure AD authentication.

4. Integrate with Nest.js:

   • Use the @nestjs/azure-func-http package to create Azure Function bindings for Nest.js.
   • Handle authentication tokens and user information in your Nest.js application.

Here's a more detailed guide:

Set up Azure Active Directory

1. Sign in to the Azure portal.
2. Go to "Azure Active Directory" > "App registrations" and register a new application.
3. Configure the required settings such as Redirect URIs, API permissions, and client secrets.

Set up Azure Functions

1. In the Azure portal, create a new Azure Functions application.
2. Configure the runtime stack (Node.js) and region.
3. Create a new Azure Function within your application.

Implement authentication logic

1. Install necessary packages:

   bashCopy code
   npm install @azure/identity
   

2. Implement the Azure Function to handle authentication:

   typescriptCopy code
   // authFunction/index.ts
   import { AzureFunction, Context, HttpRequest } from "@azure/functions";
   import { DefaultAzureCredential } from "@azure/identity";
   
   const httpTrigger: AzureFunction = async function (
     context: Context,
     req: HttpRequest
   ): Promise<void> {
     const credential = new DefaultAzureCredential();
     const accessToken = await credential.getToken("https://graph.microsoft.com/.default");
     
     // Return access token or perform additional authentication logic
     context.res = {
       status: 200,
       body: {
         access_token: accessToken.token
       }
     };
   };
   
   export default httpTrigger;
   

3. Secure the Azure Function with Azure AD authentication. You can do this by enabling authentication in the Azure portal and configuring Azure AD as the provider.

Integrate with Nest.js

1. Install necessary packages:

   bashCopy code
   npm install @nestjs/azure-func-http
   

2. Use @nestjs/azure-func-http to create Azure Function bindings for your Nest.js application:

   typescriptCopy code
   // main.azure.ts
   import { Context } from "@azure/functions";
   import { NestFactory } from "@nestjs/core";
   import { AppModule } from "./app.module";
   import { AzureFunction } from "@nestjs/azure-func-http";
   
   const createNestServer = async (expressContext: Context) => {
     const app = await NestFactory.create(AppModule);
     await app.init();
     return createAzureFunctionHandler(app, expressContext);
   };
   
   const azureFunction: AzureFunction = async (context: Context, req: any) => {
     const handler = await createNestServer(context);
     return handler(context, req);
   };
   
   export default azureFunction;
   

3. Handle authentication tokens and user information in your Nest.js application. You can use middleware to validate tokens and retrieve user information from the request context.

This setup allows you to implement serverless authentication with Azure AD in a Nest.js application deployed as Azure Functions. Adjust the implementation according to your specific requirements and security considerations