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Production Setup ​

Problem ​

In production you need structured JSON output for log aggregation, suppressed debug/info levels to reduce volume, and a set of global fields (service name, version, environment) on every entry.

Solution ​

ts
import { Logit } from '@vielzeug/logit';

const isProd = typeof process !== 'undefined' && process.env?.NODE_ENV === 'production';

export const appLog = Logit.child({
  logLevel: isProd ? 'warn' : 'debug',
  timestamp: true,
  variant: 'symbol',
  remote: isProd
    ? {
        logLevel: 'error',
        handler: async (type, data) => {
          // data: { level, message, context, env, namespace?, timestamp? }
          await fetch('/api/logs', {
            body: JSON.stringify(data),
            method: 'POST',
          });
        },
      }
    : undefined,
});

Pitfalls ​

  • JSON transport output is machine-readable but not human-readable. Do not enable it in development — always branch on process.env.NODE_ENV.
  • Global bindings set with withBindings() at startup are fixed for that logger instance. Hot reload or version bumps do not update them — the stale values persist in log entries.
  • Setting logLevel: 'error' in production suppresses warnings. Warnings often indicate misconfiguration or operational drift worth catching in staging. logLevel: 'warn' is a safer default.