Add Google Authentication

A tutorial on setting up Google authentication for the Umbraco CMS backoffice users.

The Umbraco Backoffice supports external login providers (OAuth) for performing authentication of your users. This could be any OpenIDConnect provider such as Entra ID/Azure Active Directory, Identity Server, Google, or Facebook.

In this tutorial, we will take you through the steps of setting up a Google login for the Umbraco CMS backoffice.

When you log in to the Umbraco Backoffice, you need to enter your username and password. Integrating your website with Google authentication adds a button that you can click to log in with your Google account.

Why?

I'm sure a lot of content editors and implementors of your Umbraco sites would love to have one less password to remember. Click Sign in with Google and if you are already logged in with your Google account, it will log you in directly.

What the tutorial covers

Prerequisites

For this tutorial, you need:

1. Setting up a Google OAuth API

Setup a Google Console Project

Click the project dropdown and select New Project.
Enter a Project name, Organization, and Location.
Click Create.

Enable the Google+ API

Open the newly created project from the project dropdown.
Click Enable APIs and Services.
Type Google+ API in the Search field.
Select it and then Enable it.

Before you can create the credentials, you need to configure your consent screen.

Click OAuth consent screen from the left-side navigation menu.
Choose the User Type that fits your setup.
Click Create.
Fill in the required information:
- App name
- User support email
- Developer contact information
Click Save and Continue.
Select the scopes your project needs.
Click Save and Continue.
Verify the details you have provided.
Click Back to Dashboard to complete creating the Consent screen.

Create credentials

Click Credentials from the left-side navigation menu.
Click Create Credentials.
Select OAuth Client ID from the dropdown.
Select Web Application from the Application type dropdown.
Enter the following details:
- Application Name
- Authorized JavaScript origins
- Authorized redirect URIs
Click Create.

A popup appears displaying the Client Id and Client Secret. You will need these values later while configuring your solution.

The Client Id and Client Secret can always be accessed from the Credentials tab in the APIs & Services menu.

2. Integrating Google Auth in your project

Once the Google API is set up it is time to install the Google Auth provider on the Umbraco project.

Installing a Nuget Package

You can install and manage packages in a project.

Navigate to your project/solution folder.

If you have cloned down an Umbraco Project, navigate to the src folder where you can see a .csproj file.

Open a command-line of your choice such as "Command Prompt" at the mentioned location.
Run the following command to install the Microsoft.AspNetCore.Authentication.Google package.
```
dotnet add package Microsoft.AspNetCore.Authentication.Google
```

Once the package is installed, open the .csproj file to ensure if the package reference is added:

<ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.Google" Version="8.0.3" />
</ItemGroup>

3. Configuring the solution to allow Google logins

To use an external login provider such as Google on your Umbraco CMS project, you have to implement a couple of new classes:

A custom-named configuration class.
A static extension class.

You can create these files in a location of your choice. In this tutorial, the files will be added to an ExternalUserLogin/GoogleAuthentication folder.

Create a new class:GoogleBackOfficeExternalLoginProviderOptions.cs.
Add the following code to the file:

GoogleBackOfficeExternalLoginProviderOptions.cs

using Microsoft.Extensions.Options;
using Umbraco.Cms.Core;
using Umbraco.Cms.Web.BackOffice.Security;

namespace MyCustomUmbracoProject.ExternalUserLogin.GoogleAuthentication;

public class GoogleBackOfficeExternalLoginProviderOptions : IConfigureNamedOptions<BackOfficeExternalLoginProviderOptions>
{
    public const string SchemeName = "OpenIdConnect";
    public void Configure(string? name, BackOfficeExternalLoginProviderOptions options)
    {
        ArgumentNullException.ThrowIfNull(name);

        if (name != Constants.Security.BackOfficeExternalAuthenticationTypePrefix + SchemeName)
        {
            return;
        }

        Configure(options);
    }

    public void Configure(BackOfficeExternalLoginProviderOptions options)
    {
        // Customize the login button
        options.ButtonStyle = "btn-danger";
        options.Icon = "icon-cloud";

        // The following options are only relevant if you
        // want to configure auto-linking on the authentication.
        options.AutoLinkOptions = new ExternalSignInAutoLinkOptions(

            // Set to true to enable auto-linking
            autoLinkExternalAccount: true,

            // [OPTIONAL]
            // Default: "Editor"
            // Specify User Group.
            defaultUserGroups: new[] { Constants.Security.EditorGroupAlias },

            // [OPTIONAL]
            // Default: The culture specified in appsettings.json.
            // Specify the default culture to create the User as.
            // It can be dynamically assigned in the OnAutoLinking callback.
            defaultCulture: null,

            // [OPTIONAL]
            // Enable the ability to link/unlink manually from within
            // the Umbraco backoffice.
            // Set this to false if you don't want the user to unlink 
            // from this external login provider.
            allowManualLinking: true
        )
        {
            // [OPTIONAL] Callback
            OnAutoLinking = (autoLinkUser, loginInfo) =>
            {
                // Customize the user before it's linked.
                // Modify the User's groups based on the Claims returned
                // in the external ogin info.
            },
            OnExternalLogin = (user, loginInfo) =>
            {
                // Customize the User before it is saved whenever they have
                // logged in with the external provider.
                // Sync the Users name based on the Claims returned
                // in the external login info

                // Returns a boolean indicating if sign-in should continue or not.
                return true;
            }
        };

        // [OPTIONAL]
        // Disable the ability for users to login with a username/password.
        // If set to true, it will disable username/password login
        // even if there are other external login providers installed.
        options.DenyLocalLogin = false;

        // [OPTIONAL]
        // Choose to automatically redirect to the external login provider
        // effectively removing the login button.
        options.AutoRedirectLoginToExternalProvider = false;
    }
}

Set the autoLinkExternalAccount to false in order to disable auto-linking in your implementation.

Create a new class: GoogleAuthenticationExtensions.cs.
Add the following code to the file:

GoogleAuthenticationExtensions.cs

using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Extensions;
using Microsoft.Extensions.DependencyInjection;

namespace MyCustomUmbracoProject.ExternalUserLogin.GoogleAuthentication;

public static class GoogleAuthenticationExtensions
{
    public static IUmbracoBuilder AddGoogleAuthentication(this IUmbracoBuilder builder)
    {
        // Register ProviderBackOfficeExternalLoginProviderOptions here rather than require it in startup
        builder.Services.ConfigureOptions<GoogleBackOfficeExternalLoginProviderOptions>();

        builder.AddBackOfficeExternalLogins(logins =>
        {
            logins.AddBackOfficeLogin(
                backOfficeAuthenticationBuilder =>
                {

                    // The scheme must be set with this method to work for the back office
                    var schemeName = backOfficeAuthenticationBuilder.SchemeForBackOffice(GoogleBackOfficeExternalLoginProviderOptions.SchemeName);

                    ArgumentNullException.ThrowIfNull(schemeName);

                    backOfficeAuthenticationBuilder.AddGoogle(
                        schemeName,
                        options =>
                        {
                            // Callback path: Represents the URL to which the browser should be redirected to.
                            // The default value is '/signin-google'.
                            // The value here should match what you have configured in you external login provider.
                            // The value needs to be unique.
                            options.CallbackPath = "/umbraco-google-signin";
                            options.ClientId = "YOURCLIENTID"; // Replace with your client id generated while creating OAuth client ID
                            options.ClientSecret = "YOURCLIENTSECRET"; // Replace with your client secret generated while creating OAuth client ID
                        });
                });
        });
        return builder;
    }
}

Replace YOURCLIENTID and YOURCLIENTSECRET with the values from the OAuth Client Ids Credentials window.
Update ConfigureServices in your Startup.cs class to register your configuration with Umbraco.

Startup.cs

using MyCustomUmbracoProject.ExternalUserLogin.GoogleAuthentication;

public void ConfigureServices(IServiceCollection services)
{
    services.AddUmbraco(_env, _config)
        .AddBackOffice()
        .AddWebsite()
        .AddComposers()

        // Register your new static extension class
        .AddGoogleAuthentication()

        .Build();
}