Tutorial: Handle authentication flows in an Angular SPA

Article
06/25/2024

This tutorial is part 3 of a series that demonstrates building an Angular single-page app (SPA) and preparing it for authentication. In Part 2 of this series, you created an Angular SPA and prepared it for authentication with your external tenant. In this tutorial, you'll learn how to handle authentication flows in your app by adding Microsoft Authentication Library (MSAL) components.

In this tutorial;

Add authentication flows to your application
Import MSAL components
Add routes to home and guarded components of the application.

Prerequisites

Tutorial: Prepare your external tenant to authenticate users in an Angular SPA.

Create the authentication configuration file, auth-config.ts

Create a new file called auth-config.ts in the folder src/app/ and add the following code snippet. This file contains authentication parameters. These parameters are used to initialize Angular and MSAL Angular configurations.


/**
 * This file contains authentication parameters. Contents of this file
 * is roughly the same across other MSAL.js libraries. These parameters
 * are used to initialize Angular and MSAL Angular configurations in
 * in app.module.ts file.
 */

import {
  LogLevel,
  Configuration,
  BrowserCacheLocation,
} from '@azure/msal-browser';

/**
 * Configuration object to be passed to MSAL instance on creation.
 * For a full list of MSAL.js configuration parameters, visit:
 * https://github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/lib/msal-browser/docs/configuration.md
 */
export const msalConfig: Configuration = {
  auth: {
    clientId: 'Enter_the_Application_Id_Here', // This is the ONLY mandatory field that you need to supply.
    authority: 'https://Enter_the_Tenant_Subdomain_Here.ciamlogin.com/', // Replace the placeholder with your tenant subdomain
    redirectUri: '/', // Points to window.location.origin by default. You must register this URI on Azure portal/App Registration.
    postLogoutRedirectUri: '/', // Points to window.location.origin by default.
  },
  cache: {
    cacheLocation: BrowserCacheLocation.LocalStorage, // Configures cache location. "sessionStorage" is more secure, but "localStorage" gives you SSO between tabs.
  },
  system: {
    loggerOptions: {
      loggerCallback(logLevel: LogLevel, message: string) {
        console.log(message);
      },
      logLevel: LogLevel.Verbose,
      piiLoggingEnabled: false,
    },
  },
};

/**
 * Scopes you add here will be prompted for user consent during sign-in.
 * By default, MSAL.js will add OIDC scopes (openid, profile, email) to any login request.
 * For more information about OIDC scopes, visit:
 * https://learn.microsoft.com/en-us/entra/identity-platform/permissions-consent-overview#openid-connect-scopes
 */
export const loginRequest = {
  scopes: [],
};

Replace the following values with the values from the Microsoft Entra admin center:
- Find the Enter_the_Application_Id_Here value and replace it with the Application ID (clientId) of the app you registered in the Microsoft Entra admin center.
- In authority, find Enter_the_Tenant_Subdomain_Here and replace it with the subdomain of your tenant. For example, if your tenant primary domain is contoso.onmicrosoft.com, use contoso. If you don't have your tenant name, learn how to read your tenant details.
Save the file.

Use custom domain URL (Optional)

Use a custom domain to fully brand the authentication URL. From a user perspective, users remain on your domain during the authentication process, rather than being redirected to ciamlogin.com domain name.

Use the following steps to use a custom domain:

Use the steps in Enable custom URL domains for apps in external tenants to enable custom domain URL for your external tenant.
In your authConfig.js file, locate then auth object, then:
1. Update the value of the authority property to https://Enter_the_Custom_Domain_Here/Enter_the_Tenant_ID_Here. Replace Enter_the_Custom_Domain_Here with your custom domain URL and Enter_the_Tenant_ID_Here with your tenant ID. If you don't have your tenant ID, learn how to read your tenant details.
2. Add knownAuthorities property with a value [Enter_the_Custom_Domain_Here].

After you make the changes to your authConfig.js file, if your custom domain URL is login.contoso.com, and your tenant ID is aaaabbbb-0000-cccc-1111-dddd2222eeee, then your file should look similar to the following snippet:

//...
const msalConfig = {
    auth: {
        authority: process.env.AUTHORITY || 'https://login.contoso.com/aaaabbbb-0000-cccc-1111-dddd2222eeee', 
        knownAuthorities: ["login.contoso.com"],
        //Other properties
    },
    //...
};

Import MSAL components

Open src/app/app.module.ts and add the following code snippet.

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HTTP_INTERCEPTORS, HttpClientModule } from '@angular/common/http';

import { MatToolbarModule } from "@angular/material/toolbar";
import { MatButtonModule } from '@angular/material/button';
import { MatCardModule } from '@angular/material/card';
import { MatTableModule } from '@angular/material/table';
import { MatMenuModule } from '@angular/material/menu';
import { MatDialogModule } from '@angular/material/dialog';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { MatIconModule } from '@angular/material/icon';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { HomeComponent } from './home/home.component';
import { GuardedComponent } from './guarded/guarded.component';

import {
    IPublicClientApplication,
    PublicClientApplication,
    InteractionType,
} from '@azure/msal-browser';

import {
    MSAL_INSTANCE,
    MsalGuardConfiguration,
    MSAL_GUARD_CONFIG,
    MsalService,
    MsalBroadcastService,
    MsalGuard,
    MsalRedirectComponent,
    MsalInterceptor,
    MsalModule,
} from '@azure/msal-angular';

import { msalConfig, loginRequest } from './auth-config';

/**
 * Here we pass the configuration parameters to create an MSAL instance.
    * For more info, visit: https://github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/lib/msal-angular/docs/v2-docs/configuration.md
    */
export function MSALInstanceFactory(): IPublicClientApplication {
    return new PublicClientApplication(msalConfig);
}

/**
 * Set your default interaction type for MSALGuard here. If you have any
    * additional scopes you want the user to consent upon login, add them here as well.
    */
export function MsalGuardConfigurationFactory(): MsalGuardConfiguration {
    return {
    interactionType: InteractionType.Redirect,
    authRequest: loginRequest
    };
}

@NgModule({
    declarations: [
    AppComponent,
    HomeComponent,
    GuardedComponent,
    ],
    imports: [
    BrowserModule,
    BrowserAnimationsModule,
    AppRoutingModule,
    MatToolbarModule,
    MatButtonModule,
    MatCardModule,
    MatTableModule,
    MatMenuModule,
    HttpClientModule,
    BrowserAnimationsModule,
    MatDialogModule,
    MatIconModule,
    MsalModule,
    ],
    providers: [
    {
        provide: HTTP_INTERCEPTORS,
        useClass: MsalInterceptor,
        multi: true,
    },
    {
        provide: MSAL_INSTANCE,
        useFactory: MSALInstanceFactory,
    },
    {
        provide: MSAL_GUARD_CONFIG,
        useFactory: MsalGuardConfigurationFactory,
    },
    MsalService,
    MsalBroadcastService,
    MsalGuard,
    ],
    bootstrap: [AppComponent, MsalRedirectComponent],
})
export class AppModule { }

Open src/app/app-routing.module.ts and replace the entire contents of the file with the following snippet. This will add routes to the home and guarded components.

import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { BrowserUtils } from '@azure/msal-browser';
import { MsalGuard } from '@azure/msal-angular';

import { HomeComponent } from './home/home.component';
import { GuardedComponent } from './guarded/guarded.component';

/**
 * MSAL Angular can protect routes in your application
    * using MsalGuard. For more info, visit:
    * https://github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/lib/msal-angular/docs/v2-docs/initialization.md#secure-the-routes-in-your-application
    */
const routes: Routes = [
    {
    path: 'guarded',
    component: GuardedComponent,
    canActivate: [
        MsalGuard
    ]
    },
    {
    path: '',
    component: HomeComponent,
    },
];

@NgModule({
    imports: [
    RouterModule.forRoot(routes, {
        // Don't perform initial navigation in iframes or popups
        initialNavigation:
        !BrowserUtils.isInIframe() && !BrowserUtils.isInPopup()
            ? 'enabledNonBlocking'
            : 'disabled', // Set to enabledBlocking to use Angular Universal
    }),
    ],
    exports: [RouterModule],
})
export class AppRoutingModule { }

Next step

Part 4: Sign in and sign out of the Angular SPA

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