# Logging

The server writes structured log lines in the format:

```
<timestamp> [<LEVEL>] pid=<pid> <logger>: <message>
```

The process ID in each line lets you distinguish workers in a multi-worker deployment.

## Daily file rotation

`LOG_UTC` (default `true`) controls both the timestamp timezone and the date boundary used for the daily file rollover. Set `LOG_UTC=false` to use local time for both.

The log directory (`LOG_DIR`, default `./logs`) is created on startup if it does not exist. The server fails fast if the directory cannot be created or written to.

Log files are named:

```
<LOG_DIR>/<LOG_FILE_PREFIX>.<YYYYMMDD>.log
```

for example `./logs/onetick-mcp.20260701.log`. A new file is opened when the date rolls over; restarts on the same day append to the existing file, and files are never renamed or deleted.

## uvicorn integration

When file logging is enabled, `uvicorn.error` (startup, shutdown, and error messages) is also routed to the file. `uvicorn.access` (per-request lines) is deliberately left on stdout only.

## Configuration variables

For the full list of logging environment variables, see `Logging variables` in the configuration reference.