autotel-hono

name	autotel-hono
description	OpenTelemetry middleware for Hono. Add otel() middleware to trace HTTP requests with semantic attributes, capture headers, and track request metrics.

autotel-hono

OpenTelemetry Hono middleware. One middleware call instruments all HTTP requests.

Setup

import { Hono } from 'hono';
import { otel } from 'autotel-hono';

const app = new Hono();
app.use(otel({ serviceName: 'my-api' }));

Configuration

app.use(otel({
  serviceName: 'my-api',
  captureRequestHeaders: ['x-request-id'],
  captureResponseHeaders: ['x-response-time'],
  captureActiveRequests: true,
  captureRequestDuration: true,
  spanNameFactory: (c) => `${c.req.method} ${c.req.routePath}`,
}));

What Gets Traced

• Every HTTP request gets a span with method, route, URL, status code
• Errors (5xx) are recorded as span exceptions
• Optional: request/response headers, active request count, duration histogram

Common Mistakes

• Do NOT call otel() per-route — register once with app.use(otel(...)).
• Do NOT pass a tracer unless you need a custom one — the middleware creates one from the global provider.
• Header capture requires listing header names upfront in config, not at request time.