Logs

By default the server writes plain text: what it is doing at the start, the settings it replaced and the errors, plus the lines of /log. It writes no line for each request.

LOG_FORMAT=json writes one JSON object a line, for a log aggregator that would otherwise have to parse the text. Every line has timestamp (ISO 8601, UTC), level (info, warn or error) and message; warnings and errors go to stderr, the rest to stdout. The lines of /log have the same fields. In this format every request also has a line, with method, path, status and duration_ms (the query is left out, because it can hold a token):

{"timestamp":"2026-10-19T12:34:56.789Z","level":"info","message":"GET /status/418 418","method":"GET","path":"/status/418","status":418,"duration_ms":0.215}

The effective format is logFormat in /config.