How to build Facebook 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 Facebook 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 Facebook 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 with Logto

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:

# Install the core package for accessing predefined values and types
go get github.com/logto-io/go/v2/core

# Install the client package for interacting with the Logto
go get github.com/logto-io/go/v2/client

Add github.com/logto-io/go/v2/core and github.com/logto-io/go/v2/client packages to your application code:

main.go
// main.go
package main

import (
	"github.com/gin-gonic/gin"
	// Add dependency
	"github.com/logto-io/go/v2/core"
	"github.com/logto-io/go/v2/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:

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/v2/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 Facebook 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 "Facebook".
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 Facebook login

Step 1: Set up an app on Facebook App Dashboard

Before you can use Facebook as an authentication provider, you must set up an app on the Facebook developer platform to obtain OAuth 2.0 credentials.

Register as a Facebook Developer if you don't already have an account.
Visit the Apps page.
Click your existing app or create a new one if needed.

tip:

A use case is the primary way your app will interact with Meta and determines which APIs, features, permissions, and products are available to your app. If you need social authentication only (to get email & public_profile), select "Authentication and request data from users with Facebook Login". If you want to access Facebook APIs, choose your preferred use cases - most of them also support integrating "Facebook Login for business" after app creation.

After app creation, on the app dashboard page, navigate to Use cases > Facebook Login > Settings or Facebook Login for business > Settings.
Fill in the Valid OAuth Redirect URIs with the Logto Callback URI (copy this from your Logto Facebook connector). After users sign in with Facebook, they'll be redirected here with an authorization code that Logto uses to finish authentication.
Navigate to Use cases and click Customize of your use case to add the scopes. We recommend adding email and public_profile which are required to implement Sign-in with Facebook in Logto.

Step 2: Set up Logto connector with client credentials

In the Facebook App Dashboard, click the sidebar App settings > Basic.
You will see the App ID and App secret on the panel.
Click the Show button next to the App secret input box to reveal and copy its content.
Configure your Logto Facebook connector settings:
- Fill the clientId field with the App ID.
- Fill the clientSecret field with the App secret.
- Click Save and Done in Logto to connect your identity system with Facebook.

Step 3: Configure scopes

Scopes define the permissions your app requests from users and control which private data your project can access from their Facebook accounts.

Configure scopes in Facebook App Dashboard

Navigate to Facebook App Dashboard > Use cases and click the Customize button.
Add only the scopes your app needs. Users will review and authorize these permissions on the Facebook consent screen:
- For authentication (Required): email and public_profile.
- For API access (Optional): Any additional scopes your app needs (e.g., threads_content_publish, threads_read_replies for accessing the Threads API). Browse the Meta Developer Documentation for available services.

Configure scopes in Logto

Choose one or more of the following approaches based on your needs:

Option 1: No extra API scopes needed

Leave the Scopes field in your Logto Facebook connector blank.
The default scope email public_profile will be requested to ensure Logto can get basic user info properly.

Option 2: Request additional scopes at sign-in

Enter all desired scopes in the Scopes field, separated by spaces.
Any scopes you list here override the defaults, so always include the authentication scopes: email public_profile.

Option 3: Request incremental scopes later

After the user signs in, you can request additional scopes on demand by reinitiating a federated social authorization flow and updating users' stored token set.
These additional scopes do not need to be filled in the Scopes field in your Logto Facebook connector, and can be achieved through Logto's Social Verification API.

By following these steps, your Logto Facebook connector requests exactly the permissions your app needs - no more, no less.

tip:

If your app requests these scopes to access the Facebook API and perform actions, make sure to enable Store tokens for persistent API access in Logto Facebook connector. See the next section for details.

Step 4: General settings

Here are some general settings that won't block the connection to Facebook but may affect the end-user authentication experience.

Sync profile information

In the Facebook connector, you can set the policy for syncing profile information, such as user names and avatars. Choose from:

Only sync at sign-up: Profile info is fetched once when the user first signs in.
Always sync at sign-in: Profile info is updated every time the user signs in.

Store tokens to access Facebook APIs (Optional)

If you want to access Facebook APIs and perform actions with user authorization (whether via social sign-in or account linking), Logto needs to get specific API scopes and store tokens.

Add the required scopes following the tutorial above.
Enable Store tokens for persistent API access in the Logto Facebook connector. Logto will securely store Facebook access tokens in the Secret Vault.

note:

Facebook doesn't provide refresh tokens. However, when token storage is enabled, Logto automatically requests a long-lived access token (60 days) upon user authentication. During this period, users can manually revoke access tokens, but otherwise won't need re-authorization to access Facebook APIs. Note: Don't add offline_access to the Scope field as this may cause errors.

You can use test, developer, and admin user accounts to test sign-in with the app. You can also publish the app directly so that any Facebook user can sign in.

In the Facebook App Dashboard, click the sidebar App roles > Test Users.
Click the Create test users button to create a testing user.
Click the Options button of an existing test user to see more operations, such as "Change name and password".

Usually, only test, admin, and developer users can sign in with the app. To enable normal Facebook users to sign in with the app in the production environment, you may need to publish this app.

In the Facebook App Dashboard, click the sidebar Publish.
Fill out the Privacy Policy URL and User data deletion fields if required.
Click the Save changes button at the bottom right corner.
Click the Live switch button on the app top bar.

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 Facebook connector should be available now.

Once you create a social connector successfully, you can enable it as a "Continue with Facebook" 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 Facebook connector to the "Social sign-in" section.

Testing and Validation

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

Create an application in Logto​

Integrate Go with Logto​

Installation​

Create a session storage​

Init LogtoClient​

Implement sign-in route​

Implement the callback route​

Implement sign-out route​

Checkpoint: Test your application​

Add Facebook connector​

Set up Facebook login​

Step 1: Set up an app on Facebook App Dashboard​

Step 2: Set up Logto connector with client credentials​

Step 3: Configure scopes​

Configure scopes in Facebook App Dashboard​

Configure scopes in Logto​

Step 4: General settings​

Sync profile information​

Store tokens to access Facebook APIs (Optional)​

Step 5: Test sign-in with Facebook's test users (Optional)​

Step 6: Publish Facebook sign-in settings​

Save your configuration​

Enable Facebook connector in Sign-in Experience​

Testing and Validation​

Further readings​

Create an application in Logto

Integrate Go with Logto

Installation

Create a session storage

Init LogtoClient

Implement sign-in route

Implement the callback route

Implement sign-out route

Checkpoint: Test your application

Add Facebook connector

Set up Facebook login

Step 1: Set up an app on Facebook App Dashboard

Step 2: Set up Logto connector with client credentials

Step 3: Configure scopes

Configure scopes in Facebook App Dashboard

Configure scopes in Logto

Step 4: General settings

Sync profile information

Store tokens to access Facebook APIs (Optional)

Step 5: Test sign-in with Facebook's test users (Optional)

Step 6: Publish Facebook sign-in settings

Save your configuration

Enable Facebook connector in Sign-in Experience

Testing and Validation

Further readings