You may notice that the Fly proxy prints errors to your logs. These errors now have codes!
The codes are there in a new code label. Also, they’re printed alongside the error message.
2024-04-19 12:06:45.000 [PU02] could not complete HTTP request to instance: connection closed before message completed
These codes are now documented. While the docs are sparse right now, you’ll see that some entries offer details about errors and how to troubleshoot them. Take PR01: No Healthy Machines, for example.
Why add this now?
We needed a way for our managed Postgres partner, Supabase to be able to react quickly to proxy issues on Fly.io customer deployments.
Also, error codes allow you to graph trends about specific errors without searching the error description, which can change at any time.
Let us know if this is useful for you.