Introduction

Building an authentication system is a fundamental aspect of many web applications. In this guide, you'll learn how to create a basic authentication system in Go to secure your web application's endpoints. We'll cover user registration, login, session management, and provide sample code for each step.


Prerequisites

Before getting started, ensure you have Go installed on your system. Basic knowledge of Go and web development concepts will be helpful.


User Registration

The first step in building an authentication system is allowing users to register. You'll need to capture user data and store it securely in a database. Here's an example of registering a user using the Gorilla Mux router and PostgreSQL database:

// Define a User struct
type User struct {
    ID       int
    Username string
    Password string
}
// Create a registration handler
func RegisterHandler(w http.ResponseWriter, r *http.Request) {
    // Parse and validate user input
    // Hash the password securely
    // Store the user in the database
    // Set a session cookie for the user
}

User Login

Once users are registered, they should be able to log in securely. In the login handler, you'll verify the user's credentials and create a session. Here's an example of a login handler:

// Create a login handler
func LoginHandler(w http.ResponseWriter, r *http.Request) {
    // Verify user credentials
    // Create a session for the user
    // Set a session cookie
}

Session Management

Managing user sessions is crucial for authentication. You'll typically use cookies or tokens to maintain user sessions. Here's an example of creating and validating user sessions using Gorilla Sessions:

// Set up Gorilla Sessions
store := sessions.NewCookieStore([]byte("your-secret-key"))
// Create a session for the user
session, _ := store.Get(r, "user-session")
session.Values["user_id"] = user.ID
session.Save(r, w)
// Validate the user's session
session, _ := store.Get(r, "user-session")
userID := session.Values["user_id"]

Securing Endpoints

To secure your application's endpoints, you'll need to check the user's session on each request. Here's an example of a middleware to ensure user authentication:

// Create an authentication middleware
func AuthenticationMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        // Check the user's session
        // If the user is authenticated, proceed to the next handler
        // If not, redirect to the login page
    })
}

Conclusion

Building a basic authentication system in Go is essential for securing your web applications. This guide covered user registration, login, session management, and securing endpoints. With this knowledge, you can create secure and user-friendly authentication systems for your Go applications.


Further Resources

To further explore Go web development and authentication systems, consider the following resources: