API Logging That Actually Helps: A Minimal Field Schema

Logs shouldn't be noise. They should answer one question — what happened, where, and why — in minutes, not days.

The minimal set of fields

If you log API requests, start with at least this:

• request_id (correlation across every service)
• method + route (not just the URL as a string)
• status_code
• duration_ms (ideally with a breakdown: upstream/db/cache)
• user_id / account_id / session_id (context)
• error_class / error_message (when there is an error)
• upstream_status / upstream_duration_ms (when you call external services)

Why it works

Because you can:

• assemble a single request trace by request_id
• see exactly where the time goes
• tell a "slow database" apart from "slow code"
• find a regression fast after a release

The next step

If production is a black box right now, start with logging and dashboards.

Case study: how we wired up Grafana + Loki and started seeing every API method