How next auth extends the session at regular intervals

NextAuth.js uses a mechanism called "session rolling" to extend the session expiry after a regular interval. This ensures that active users remain logged in as long as they are actively using the application, without having to frequently re-authenticate.

How Session Rolling Works in NextAuth.js

1. Session Token with Expiry:

   • When a user signs in, NextAuth.js creates a session token (often a JSON Web Token or JWT) that includes an expiry time.
   • This session token is stored in a cookie on the client-side.

2. User Activity Detection:

   • Each time the user makes a request to the server (such as navigating to a new page or performing an API call), the session token is sent along with the request.
   • The server verifies the session token to check if it is still valid.

3. Extending Session Expiry:

   • If the session token is valid and the session rolling mechanism is enabled, the server will extend the session expiry by resetting the expiry time.
   • This involves generating a new session token with an updated expiry time and sending it back to the client.
   • The client replaces the old session token with the new one in the cookie.

4. Session Expiry Update:

   • The expiry time is typically extended by a predefined amount, ensuring the session remains active as long as the user continues interacting with the application.

Why Session Rolling is Needed

1. User Experience:

   • Session rolling improves user experience by preventing unexpected logouts. Users can stay logged in as long as they are actively using the application, avoiding the need to re-authenticate frequently.

2. Security:

   • While it keeps active users logged in, session rolling also ensures that sessions eventually expire for inactive users, reducing the risk of session hijacking if a user's session token is somehow compromised.

3. Session Management:

   • It provides a balance between security and usability. Sessions for active users are extended, while inactive sessions are allowed to expire, freeing up resources on the server.

Example Configuration

Here is an example of how you might configure session rolling in NextAuth.js:

import NextAuth from "next-auth";
import Providers from "next-auth/providers";

export default NextAuth({
  providers: [
    // Define authentication providers here
  ],
  session: {
    // Define session rolling interval (in seconds)
    maxAge: 30 * 24 * 60 * 60, // Session expires after 30 days of inactivity
    updateAge: 24 * 60 * 60, // Extend session expiry every 24 hours
  },
  callbacks: {
    async session(session, token) {
      // This callback is called whenever a session is checked
      // You can implement additional logic here if needed
      return session;
    },
  },
});

Configuration Options

• maxAge: Defines the maximum age of the session in seconds. If the session is inactive for this period, it will expire.
• updateAge: Defines the interval in seconds after which the session expiry should be extended. For example, setting this to 86400 seconds (24 hours) means that the session expiry will be extended if the user is active within this interval.