@onelog/node

Unified Node.js SDK for tracing, logging, HTTP calls, and exception capture. Drop it into any Express-based service to get consistent telemetry with one import.

Install

npm install @onelog/node

Quickstart

import express from 'express';
import { sdkStartPromise, instrumentApp, createLogger, errorMiddleware, httpCall } from '@onelog/node';

const logger = createLogger();
const app = express();
const PORT = process.env.PORT || 8700;

app.use(express.json());
instrumentApp(app, logger, process.env.MAIN_MODULE);

app.get('/health', (_req, res) => res.json({ status: 'ok', module: process.env.MAIN_MODULE }));

app.post('/do', async (req, res, next) => {
  try {
    const reply = await httpCall(
      process.env.PEER_URL || 'http://localhost:3001/work',
      { method: 'POST', body: req.body },
      logger,
      { flow: 'demo' }
    );
    res.json({ ok: true, reply });
  } catch (err) { next(err); }
});

app.use(errorMiddleware(logger));

sdkStartPromise.finally(() => {
  app.listen(PORT, () => logger.info({ port: PORT }, 'Service started'));
});

What’s inside

• Tracing (sdkStartPromise, instrumentApp) — boots OpenTelemetry Node SDK with HTTP/Express/undici auto-instrumentation and renames spans to [module] METHOD /path while adding module.name.
• Logging (createLogger) — Pino with dual transports: OTLP-friendly output plus pretty console, pre-tagged with env/app/module.
• Exceptions (errorMiddleware) — records exceptions on the active span, sets span status to ERROR, logs details, and returns JSON.
• HTTP calls (httpCall) — fetch wrapper with consistent logging, JSON handling, and error propagation.

Environment variables

• PORT — HTTP port for your service.
• MAIN_MODULE — logical module name (shown in spans and logs).
• MAIN_APP — application/system name.
• MAIN_ENV — environment (production/staging/dev).
• OTEL_EXPORTER_OTLP_ENDPOINT — OTLP HTTP endpoint (e.g., http://localhost:4318, no trailing slash).
• OTEL_SERVICE_NAME — service name for tracing.
• OTEL_NAMESPACE / OTEL_SERVICE_NAMESPACE — optional namespace.
• Downstream URLs as needed: PEER_URL, etc.
• ONELOG_EXPRESS_LAYERS — set to true to include middleware/request_handler spans (defaults to lean mode without them).
• HTTP_PROXY / HTTPS_PROXY (also lowercase variants) — if present, outbound HTTP (including OTLP export) uses the proxy.

Build (for contributors)

npm install
npm run build   # tsup → dist/index.{mjs,cjs} + types, minified

Notes

• Requires Node 18+.
• Auto-instrumentation is focused on HTTP/Express/undici; noisy instrumentations are off by default.