What methods do you use or know for implementing user login processes?

To implement user login in Go, the following methods are usually used:

• Authentication with username and password with hashed password storage (e.g., bcrypt).
• Using JWT (JSON Web Tokens) to create a session token after successful login.
• OAuth2 for authorization through third-party services (Google, Facebook, etc.).
• Sessions with cookies for web applications.

Example of simple login with password verification:

import (
    "golang.org/x/crypto/bcrypt"
    "net/http"
)

func loginHandler(w http.ResponseWriter, r *http.Request) {
    username := r.FormValue("username")
    password := r.FormValue("password")

    // Retrieve hashed password from DB by username
    hashedPassword := getHashedPasswordFromDB(username)

    err := bcrypt.CompareHashAndPassword([]byte(hashedPassword), []byte(password))
    if err != nil {
        http.Error(w, "Invalid credentials", http.StatusUnauthorized)
        return
    }

    // Create session or JWT and send to client
}

Thus, the process includes password verification, token or session creation, and user state management.