How to handle JWT expiration in Supabase?

 

Step 1: Understand JWT in Supabase

 

JSON Web Tokens (JWT) are used for performing authentication and securing APIs. Supabase uses JWT for managing session state. Each JWT has an expiration time, which determines how long the token is valid.

 

Step 2: Configure JWT Expiration in Supabase

 

To handle JWT expiration, first you need to configure the expiration settings in Supabase:

• Navigate to your Supabase project dashboard.
• Go to the "Settings" tab and select "Auth Settings".
• Find the section named "JWT Expiry".
• Set the desired expiry time in seconds based on your application's needs. For example, set it to 3600 seconds for a 1-hour expiry.

 

Step 3: Detect JWT Expiration in Your Application

 

In your application, detect when a JWT has expired. Handle this by:

Using the Supabase client to check the current user's session state:

import { createClient } from '@supabase/supabase-js'

const supabase = createClient('your-supabase-url', 'your-supabase-key')

// Check the current user session
const session = supabase.auth.session()

if (!session) {
    console.log("No active session found. JWT may have expired.")
} else {
    const expiresAt = session.expires\_at
    const currentTime = Date.now() / 1000

    if (expiresAt < currentTime) {
        console.log("Session has expired.")
    } else {
        console.log("Session is still active.")
    }
}

 

Step 4: Refreshing the JWT

 

Implement JWT refresh functionality to maintain user sessions without requiring them to log in again:

• When the JWT expiration is approaching, refresh the token automatically:

async function refreshToken() {
    const { user, error } = await supabase.auth.signIn({
        refreshToken: supabase.auth.session().refresh\_token,
    })

    if (error) {
        console.log("Error refreshing token:", error.message)
    } else {
        console.log("Token successfully refreshed. New session:", user)
    }
}

• Invoke this function before the JWT expires or when certain actions require re-authentication.

 

Step 5: Handle Automatic JWT Refresh

 

To improve UX, automatically monitor token validity and refresh tokens in the background using a library like setInterval():

setInterval(() => {
    const currentTime = Date.now() / 1000
    const session = supabase.auth.session()

    if (session && session.expires\_at - currentTime < 600) { // Refresh if expiring within 10 mins
        refreshToken()
    }
}, 300000) // Check every 5 minutes

 

Step 6: Secure Your Refresh Strategy

 

Ensure that only safe environments can refresh JWTs by implementing:

• HTTPS for all API interactions.
• OAuth 2.0 or other secure flow using Supabase auth functions to further protect the refresh token mechanism.

This maintains secure JWT handling without constantly requiring user credentials.

 

Step 7: Logs and Monitoring

 

Add logs to monitor the expiration and refresh flow. Use Supabase or third-party logging tools to track any unexpected behavior:

• Track successful token refresh events.
• Monitor any refresh errors to alert you and help diagnose potential issues.

 

By following these comprehensive steps, you can effectively handle JWT expiration in Supabase and maintain secure and seamless user authentication in your application.