README.md

title	Google OAuth2
keywords	oauth2 google authentication
description	Implementing Google OAuth2 authentication.

Fiber with Google OAuth2

This example demonstrates how to implement Google OAuth2 authentication in a Fiber application.

Prerequisites

• Go 1.25 or higher
• Go modules

Setup

1. Clone the repository:

   git clone https://github.com/gofiber/recipes.git
   cd recipes/oauth2-google

2. Install dependencies:

   go mod tidy

3. Obtain OAuth credentials from Google Developers Console.

4. Create a .env file in the root directory and add your Google OAuth credentials:

   APP_PORT=3300
   GOOGLE_CLIENT_ID=your_client_id
   GOOGLE_CLIENT_SECRET=your_client_secret
   GOOGLE_REDIRECT_URL=http://localhost:3300/api/auth/google/callback

Running the Application

1. Run the application:

   go run main.go

2. The server will start on http://localhost:3300.

Endpoints

Method	URL	Description
GET	/api/	Redirects to Google login URL
GET	/api/auth/google/callback	Handles Google OAuth2 callback and returns user's email

Example Requests

Redirect to Google Login

curl -X GET http://localhost:3300/api/

Google OAuth2 Callback

curl -X GET http://localhost:3300/api/auth/google/callback?state=state&code=code

Security

OAuth2 State Validation (CSRF Protection)

The login handler generates a random state parameter and stores it in an HttpOnly, Secure, SameSite=Lax cookie before redirecting to Google. The callback handler compares the state query parameter returned by Google against the stored cookie value and returns 403 Forbidden if they do not match. This prevents Cross-Site Request Forgery (CSRF) attacks against the OAuth2 flow.

Packages Used

• Godotenv
• Fiber
• OAuth2