Debugging Refresh Token Expiry with Auth0

TL;DR

• Tokens don’t automatically revoke server-side; it’s client-side expiry and error paths handling.
• Perpetual loading issue was traced to unhandled, undefined values from failed token refresh:
  • Client assumed token refresh without explicit validation.
  • Debugging revealed logic misstep, not accounting for expired tokens.
• Need for robust error handling and routine testing for token lifetime configurations.

Dive into Token Handling with Auth0

Today was a deep dive of exploring a bug in our app dealing with token expiry and perpetual loading screens. When opening the app freshly, there was no token stored in Auth0 due to an expired and subsequently auto-revoked local token. This led me down the path of troubleshooting how our app handles token lifecycle respecting Auth0’s token management.

Understanding Token Revocation

First, I verified my understanding of how Auth0 treats expired tokens. Auth0 doesn’t proactively revoke tokens; rather, an expired refresh token simply fails on use. This means for our app, an expired token should either refresh successfully or prompt a login, but it seems neither was happening seamlessly.

Debugging the Flow

Upon opening the app, the client checks for existing tokens. If the local storage token is expired, our app attempts a refresh. However, for some reason, this flow resulted in an error and defaulted to a confusing perpetual loading state.

1. Initial Exploration: I linked the issue to refresh token expiration acting unnoticed due to our test phone inactivity. The token lifetime ran out, resulting in the client failing to refresh.
2. Error Path Discovery: Error thrown during token handling did not trigger the desired fallback to initiate a re-login. This lack of explicit error handling returned undefined values, leading to a perpetual load.
3. Math & Calendar Verification: I calculated our refresh token lifespan, verifying if inactivity was a factor. Our refresh token was at the edge of expiry, highlighting possible scenarios like Idana not utilizing the test device within these limits.

Recap of Findings

• Client Logic Gap: The app did not have a robust fallback when encountering undefined token retrieval. A missing hard rethrow and checkpoint for new login if refresh fails should address this.
• Token Expiry Miscomprehension: Our understanding of refresh token handling needed realigning to handle edge cases without automatic expiry assumptions.

I realized the perpetual loading was a symptom of opaque error paths devouring possible intervention points.

Forward Steps

I’ll introduce thorough checks for token validity before attempting refreshes and improve error messaging along with a clear pathway to reauthentication. Closing this loop ensures the perpetual loading ceases, providing a cleaner experience for our users. Planning collaborative testing to avoid hitting expiry and catching these nuances early is the next step.

This session reinforced the critical nature of clear, encompassing error handling and diligent testing around identity management with third-party auth services like Auth0.