Logging

timeserver uses pino for structured JSON logging. Every log line is a JSON object, which makes logs easy to query in tools like Grafana Loki, Datadog, or CloudWatch.

Log levels

Controlled by the LOG_LEVEL environment variable. Valid values (in order of verbosity):

Level	When to use
trace	Very detailed internal flow
debug	Development diagnostics
info	Normal operational events (default)
warn	Unexpected but recoverable situations
error	Errors that need attention
silent	Suppress all output

LOG_LEVEL=debug npm run dev

Log format

Each line is a JSON object written to stdout. Example request log:

{
  "level": 30,
  "time": 1731678600000,
  "pid": 12345,
  "hostname": "timeserver-abc12",
  "msg": "request completed",
  "req": {
    "method": "GET",
    "url": "/api/v1/time",
    "remoteAddress": "127.0.0.1"
  },
  "res": {
    "statusCode": 200
  },
  "responseTime": 3.5
}

pino-http

HTTP request/response logging is handled by pino-http, which automatically logs every incoming request and its response status and duration.

No console.log

ESLint is configured with no-console: error — all logging must go through the pino logger. This prevents unstructured output from leaking into production logs.