Frontend Backend Correlated Logging: Browser Fetch Request IDs and Server Logs

To correlate browser fetch request IDs with server logs, each browser fetch should receive a unique request ID, which is then passed to the backend through a standard HTTP header. This ID should also be included in structured logs on both sides of the request, ensuring that the same ID is present in both the client-side fetch and the server-side logs.

By maintaining this shared correlation key, it becomes easier to trace the flow of a request from the browser to the server and back, even in complex systems where multiple events may occur.

The implementation should be straightforward, with the browser generating a non-secret request ID for each outbound fetch and attaching it to the appropriate headers. The server, upon receiving the request, should validate or replace any malformed IDs and log the accepted value along with other relevant information such as the route, outcome, and duration.

Additionally, a separate flag-evaluation ID should be used to identify the specific pricing decision and its corresponding rule version. This helps in verifying the pricing decision in case of rollbacks, ensuring that the rollback process can be accurately traced and verified. The IDs should not contain sensitive information like user emails or tokens, as they serve solely as correlation keys to link events together.

The correlation process is crucial for debugging and troubleshooting issues, especially when dealing with pricing rules and financial transactions. By having a clear and consistent way to link browser requests with backend logs, support teams can quickly identify and resolve issues, ensuring a smooth user experience and accurate financial transactions.