@flarelog/sdk

---

@flarelog/sdk / workerFetch

Function: workerFetch()

workerFetch<T>(logger, handler): WorkerFetchHandler<T>

Defined in: frameworks/cf-workers.ts:39

Wrap a Cloudflare Worker fetch handler with automatic OTel instrumentation.

v2 — emits an OTel SERVER span for every request:

• Extracts W3C traceparent from incoming headers (or starts a new trace)
• Creates a SPAN_KIND_SERVER span: GET /api/users
• Sets http.request.method, url.path, url.full, http.response.status_code, etc.
• All logs emitted inside the handler carry the span's traceId + spanId
• Records exceptions on the span and sets span status
• Flushes telemetry via ctx.waitUntil() (with blocking fallback for tests)

Type Parameters

T

T = Response

Parameters

logger

FlareLog

handler

WorkerFetchHandler<T>

Returns

WorkerFetchHandler<T>

Examples

import { flarelog, workerFetch } from "@flarelog/sdk";

// No API key needed — defaults to console output
const logger = flarelog({});

export default {
  fetch: workerFetch(logger, async (request, env, ctx) => {
    return new Response("Hello");
  }),
};

Fan-out to Flarelog + Grafana

// wrangler.toml:
//   FLARELOG_API_KEY = "fl_your_key"
//   OTEL_EXPORTER_OTLP_ENDPOINT = "https://otlp-gateway-prod-eu-west-0.grafana.net"
//   OTEL_EXPORTER_OTLP_HEADERS = "Authorization=Basic <base64>"
const logger = flarelog({});
// → ships to both Flarelog dashboard and Grafana Cloud, plus console