How to build Apple sign-in with Go

For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

In this article, we will go through the steps to quickly build the Apple sign-in experience (user authentication) with Go and Logto.

Prerequisites

A running Logto instance. Check out the introduction page to get started.
Basic knowledge of Go.
A usable Apple account.

Create an application in Logto

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Traditional web application, simply follow these steps:

Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button.
In the opening modal, click the "Traditional web" section or filter all the available "Traditional web" frameworks using the quick filter checkboxes on the left. Click the "Go" framework card to start creating your application.
Enter the application name, e.g., "Bookstore," and click "Create application".

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Go SDK

tip:

The following demonstration is built upon the Gin Web Framework. You may also integrate Logto into other frameworks by taking the same steps.
The Go sample project is available on our Go SDK repo.

Installation

Execute in the project root directory:

go get github.com/logto-io/go

Add the github.com/logto-io/go/client package to your application code:

main.go
// main.go
package main

import (
	"github.com/gin-gonic/gin"
	// Add dependency
	"github.com/logto-io/go/client"
)

func main() {
	router := gin.Default()
	router.GET("/", func(c *gin.Context) {
		c.String(200, "Hello Logto!")
	})
	router.Run(":3000")
}

Create a session storage

In traditional web applications, the user authentication information will be stored in the user session.

Logto SDK provides a Storage interface, you can implement a Storage adapter based on your web framework so that the Logto SDK can store user authentication information in the session.

note:

We do NOT recommend using cookie-based sessions, as user authentication information stored by Logto may exceed the cookie size limit. In this example, we use memory-based sessions. You can use Redis, MongoDB, and other technologies in production to store sessions as needed.

The Storage type in the Logto SDK is as follows:

github.com/logto-io/client/storage.go
package client

type Storage interface {
	GetItem(key string) string
	SetItem(key, value string)
}

We use github.com/gin-contrib/sessions middleware as an example to demonstrate this process.

Apply the middleware to the application, so that we can get the user session by the user request context in the route handler:

main.go
package main

import (
	"github.com/gin-contrib/sessions"
	"github.com/gin-contrib/sessions/memstore"
	"github.com/gin-gonic/gin"
	"github.com/logto-io/go/client"
)

func main() {
	router := gin.Default()

	// We use memory-based session in this example
	store := memstore.NewStore([]byte("your session secret"))
	router.Use(sessions.Sessions("logto-session", store))

	router.GET("/", func(ctx *gin.Context) {
		// Get user session
		session := sessions.Default(ctx)
		// ...
		ctx.String(200, "Hello Logto!")
	})
	router.Run(":3000")
}

Create a session_storage.go file, define a SessionStorage and implement the Logto SDK's Storage interfaces:

session_storage.go
package main

import (
	"github.com/gin-contrib/sessions"
)

type SessionStorage struct {
	session sessions.Session
}

func (storage *SessionStorage) GetItem(key string) string {
	value := storage.session.Get(key)
	if value == nil {
		return ""
	}
	return value.(string)
}

func (storage *SessionStorage) SetItem(key, value string) {
	storage.session.Set(key, value)
	storage.session.Save()
}

Now, in the route handler, you can create a session storage for Logto:

session := sessions.Default(ctx)
sessionStorage := &SessionStorage{session: session}

Init LogtoClient

First, create a Logto config:

main.go
func main() {
	// ...
	logtoConfig := &client.LogtoConfig{
		Endpoint:  "<your-logto-endpoint>", // E.g. http://localhost:3001
		AppId:     "<your-application-id>",
		AppSecret: "<your-application-secret>",
	}
	// ...
}

tip:

You can find and copy "App Secret" from application details page in Admin Console:

Then, you can create a LogtoClient for each user request with the Logto config above:

main.go
func main() {
	// ...

	router.GET("/", func(ctx *gin.Context) {
		// Create LogtoClient
		session := sessions.Default(ctx)
		logtoClient := client.NewLogtoClient(
			logtoConfig,
			&SessionStorage{session: session},
		)

		// Use Logto to control the content of the home page
		authState := "You are not logged in to this website. :("

		if logtoClient.IsAuthenticated() {
			authState = "You are logged in to this website! :)"
		}

		homePage := `<h1>Hello Logto</h1>` +
			"<div>" + authState + "</div>"

		ctx.Data(http.StatusOK, "text/html; charset=utf-8", []byte(homePage))
	})

	// ...
}

After the redirect URI is configured, we add a sign-in route to handle the sign-in request and also add an sign-in link on the home page:

main.go
func main() {
	// ...

	// Add a link to perform a sign-in request on the home page
	router.GET("/", func(ctx *gin.Context) {
		// ...
		homePage := `<h1>Hello Logto</h1>` +
			"<div>" + authState + "</div>" +
			// Add link
			`<div><a href="/sign-in">Sign In</a></div>`

		ctx.Data(http.StatusOK, "text/html; charset=utf-8", []byte(homePage))
	})

	// Add a route for handling sign-in requests
	router.GET("/sign-in", func(ctx *gin.Context) {
		session := sessions.Default(ctx)
		logtoClient := client.NewLogtoClient(
			logtoConfig,
			&SessionStorage{session: session},
		)

		// The sign-in request is handled by Logto.
		// The user will be redirected to the Redirect URI on signed in.
		signInUri, err := logtoClient.SignIn("http://localhost:3000/callback")
		if err != nil {
			ctx.String(http.StatusInternalServerError, err.Error())
			return
		}

		// Redirect the user to the Logto sign-in page.
		ctx.Redirect(http.StatusTemporaryRedirect, signInUri)
	})

	// ...
}

Now, when your user visit http://localhost:3000/sign-in, the user will be redirected to the Logto sign-in page.

Implement the callback route

When the user signs in successfully on the Logto sign-in page, Logto will redirect the user to the Redirect URI.

Since the redirect URI is http://localhost:3000/callback, we add the /callback route to handle the callback after signing in.

main.go
func main() {
	// ...

	// Add a route for handling sign-in callback requests
	router.GET("/callback", func(ctx *gin.Context) {
		session := sessions.Default(ctx)
		logtoClient := client.NewLogtoClient(
			logtoConfig,
			&SessionStorage{session: session},
		)

		// The sign-in callback request is handled by Logto
		err := logtoClient.HandleSignInCallback(ctx.Request)
		if err != nil {
			ctx.String(http.StatusInternalServerError, err.Error())
			return
		}

		// Jump to the page specified by the developer.
		// This example takes the user back to the home page.
		ctx.Redirect(http.StatusTemporaryRedirect, "/")
	})

	// ...
}

Implement sign-out route

Similar to the sign-in flow, when the user signs out, Logto will redirect the user to the post sign-out redirect URI.

Now, let's add the sign-out route to handle the sign-out request and also add a sign-out link on the home page:

main.go
func main() {
	// ...

	// Add a link to perform a sign-out request on the home page
	router.GET("/", func(ctx *gin.Context) {
		// ...
		homePage := `<h1>Hello Logto</h1>` +
			"<div>" + authState + "</div>" +
			`<div><a href="/sign-in">Sign In</a></div>` +
			// Add link
			`<div><a href="/sign-out">Sign Out</a></div>`

		ctx.Data(http.StatusOK, "text/html; charset=utf-8", []byte(homePage))
	})

	// Add a route for handling signing out requests
	router.GET("/sign-out", func(ctx *gin.Context) {
		session := sessions.Default(ctx)
		logtoClient := client.NewLogtoClient(
			logtoConfig,
			&SessionStorage{session: session},
		)

		// The sign-out request is handled by Logto.
		// The user will be redirected to the Post Sign-out Redirect URI on signed out.
		signOutUri, signOutErr := logtoClient.SignOut("http://localhost:3000")

		if signOutErr != nil {
			ctx.String(http.StatusOK, signOutErr.Error())
			return
		}

		ctx.Redirect(http.StatusTemporaryRedirect, signOutUri)
	})

	// ...
}

After the user makes a signing-out request, Logto will clear all user authentication information in the session.

Checkpoint: Test your application

Now, you can test your application:

Run your application, you will see the sign-in button.
Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
After you signed in, you will be redirected back to your application and see the sign-out button.
Click the sign-out button to clear token storage and sign out.

Add Apple connector

To enable quick sign-in and improve user conversion, connect with Go as an identity provider. The Logto social connector helps you establish this connection in minutes by allowing several parameter inputs.

To add a social connector, simply follow these steps:

Navigate to Console > Connectors > Social Connectors.
Click "Add social connector" and select "Apple".
Follow the README guide and complete required fields and customize settings.

note:

If you are following the in-place Connector guide, you can skip the next section.

Set up Apple Sign-in

note:

Apple sign-in is required for AppStore if you have other social sign-in methods in your app. Having Apple sign-in on Android devices is great if you also provide an Android app.

You need to enroll Apple Developer Program before continuing.

caution:

Even if you want to implement Sign in with Apple on a web app only, you still need to have an existing app that embraces the AppStore ecosystem (i.e., have a valid App ID).

You can do it via Xcode -> Project settings -> Signing & Capabilities, or visit Certificates, Identifiers & Profiles.

Enable Sign in with Apple

See the "Enable an App ID" section in Apple official docs for more info.

Create an identifier

Visit Certificates, Identifiers & Profiles, then click the "+" button next to "Identifier".
In the "Register a new identifier" page, choose "Services IDs" and click "Continue".
Fill out "Description" and "Identifier" (E.g., Logto Test and io.logto.test), then click "Continue".
Double-check the info and click "Register".

Click the identifier you just created. Check "Sign in with Apple" on the details page and click "Configure".

Enable Sign in with Apple

In the opening modal, select the App ID you just enabled Sign in with Apple.

Enter the domain of your Logto instance without protocol and port, e.g., your.logto.domain; then enter the "Return URL" (i.e., Redirect URI), which is the Logto URL with /callback/${connector_id}, e.g., https://your.logto.domain/callback/apple-universal. You can get the randomly generated connector_id after creating Apple connector in Admin Console.

domain-and-url

Click "Next" then "Done" to close the modal. Click "Continue" on the top-right corner, then click "Save" to save your configuration.

caution:

Apple does NOT allow Return URLs with HTTP protocol and localhost domain.

If you want to test locally, you need to edit /etc/hosts file to map localhost to a custom domain and set up a local HTTPS environment. mkcert can help you for setting up local HTTPS.

Configure scope

To get user's email from Apple, you need to configure the scope to include email. For both email and name, you can use name email as the scope. See Apple official docs for more info.

note:

The user may choose to hide their email address from your app. In this case, you will not be able to retrieve the real email address. An email address like [email protected] will be returned instead.

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the Apple connector should be available now.

Once you create a social connector successfully, you can enable it as a "Continue with Apple" button in Sign-in Experience.

Navigate to Console > Sign-in experience > Sign-up and sign-in.
(Optional) Choose "Not applicable" for sign-up identifier if you need social login only.
Add configured Apple connector to the "Social sign-in" section.

Sign-in Experience tab

Testing and Validation

Return to your Go app. You should now be able to sign in with Apple. Enjoy!

Create an application in Logto​

Integrate Go SDK​

Installation​

Create a session storage​

Init LogtoClient​

Implement sign-in route​

Implement the callback route​

Implement sign-out route​

Checkpoint: Test your application​

Add Apple connector​

Set up Apple Sign-in​

Enable Sign in with Apple for your app​

Create an identifier​

Enable Sign in with Apple for your identifier​

Configure scope​

Save your configuration​

Enable Apple connector in Sign-in Experience​

Testing and Validation​

Further readings​

Create an application in Logto

Integrate Go SDK

Installation

Create a session storage

Init LogtoClient

Implement sign-in route

Implement the callback route

Implement sign-out route

Checkpoint: Test your application

Add Apple connector

Set up Apple Sign-in

Enable Sign in with Apple for your app

Create an identifier

Enable Sign in with Apple for your identifier

Configure scope

Save your configuration

Enable Apple connector in Sign-in Experience

Testing and Validation

Further readings