Log slow API requests with server spans and client timing

2026-10-21 14:45:19 -07:00
parent 671165ec71
commit b4c1dbab37
31 changed files with 458 additions and 185 deletions
@@ -18,6 +18,10 @@ The service always runs from the app: `/Applications/Byre.app/Contents/Helpers/b

 `byre serve` exits when its executable is replaced (logging `executable replaced, exiting`) and launchd starts the new one. A missing path counts as not yet replaced, so the moment in `install.sh` between removing the old bundle and moving the new one in doesn't trigger it. The service log is owner-only (0600), including existing logs: Tailscale can put a sign-in URL there. Logs go to `~/Library/Logs/byre.log`; `launchctl print gui/$(id -u)/run.fc.byre` shows the service.

+## Slow requests
+
+An API request that takes 200 ms or more is logged on both ends. The server's line, `request slow`, in `byre.log`, has the handler's time and its spans: each git process, SQL begin, exec and query, the wait for the store's write lock, and the tailnet `whois`. Every response also carries these spans in a `Server-Timing` header. On the client, `log show --start <time> --predicate 'subsystem == "run.fc.byre.mac" AND eventMessage BEGINSWITH "request slow"'` shows the app's line, which splits the request's time into `queue` (waiting for a connection), `connect`, `network` (time to the first byte, less the server's time), `server`, `download` and `app` (how long the main actor took to pick up work once the response ended). Event streams and websockets are left out.
+
 ## Tailnet

 byre runs its own tailnet node with `tsnet`; it doesn't use the Tailscale app. The app connects at the root of the node's `ts.net` name on 443, not under a path: the API uses absolute paths and the app takes an origin with no path. Tailnet access requires a user identity; a tagged node gets 403. Local scripts can also check server status and run client commands through the authenticated loopback address.