Fernando Solution
The Fernando Solution is a mechanism for detecting whether a client accepts cookies. This check prevents bot traffic—which often rejects cookies—from causing endless redirect loops and noisy errors in Datadog.
How it works
- On the client’s first request to the monolith, the system sets a cookie named
__sso_cookie_checkerwith the user’s IP as its value. - The client is redirected to the Remix-SSO app.
- Remix-SSO checks if the cookie exists:
- If the cookie is present, the system assumes the client supports cookies and proceeds with the normal login flow (e.g., IP-based login).
- If the cookie is missing, the system stops the login attempt. This prevents errors and avoids infinite redirect loops.
Background
The solution was first proposed during a debugging session led by Fernando. It was designed to filter out bot traffic that does not support cookies, which had been obscuring real errors in Datadog.