Cloudflare

Use the Middleware APM package for Cloudflare Workers to send traces, metrics and application logs from your Workers to Middleware. The table shows which data types the integration collects.

1. Prerequisites#

Wrangler installed v2.2 or newer. Check your version:

wrangler version

2. Install#

npm i @middleware.io/agent-apm-worker

import { init, track } from '@middleware.io/agent-apm-worker';

init({
  serviceName: "{APM-SERVICE-NAME}",
  accountKey: "<MW_API_KEY>",
  target: "https://{ACCOUNT-UID}.middleware.io",
  consoleLogEnabled: false, // set true to see instrumented logs locally
});

3. Capture application data#

• Trace the incoming request Use track(request, ctx) and return via sdk.sendResponse(response):
  js

  export default {
     async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
        const sdk = track(request, ctx);
  
        // your app logic
        const response = new Response("ok", { status: 200 });
  
        return sdk.sendResponse(response);
     },
  };

• Trace upstream calls (HTTP client propagation) If your Worker calls an external API, use sdk.fetch(...) to propagate context automatically:
  js

  const sdk = track(request, ctx);
  const url = new URL(request.url);
  const upstream = await sdk.fetch(`https://httpbin.org${url.pathname}`);
  return sdk.sendResponse(upstream);

4. Custom logs (optional)#

Emit structured logs correlated with the current trace:

// sdk.logger.SEVERITY(message, attributes?)
sdk.logger.error("error test");
sdk.logger.error("error with attributes", { "log.file.name": "error.log" });
sdk.logger.info("info test");
sdk.logger.debug("debug test");
sdk.logger.warn("warn test");

5. Configure secrets & env (Wrangler)#

Use Wrangler vars/secrets to avoid hardcoding keys:

• wrangler.toml
  js

  name = "my-worker"
     main = "src/index.ts"
     compatibility_date = "2024-12-01"
  
     [vars]
     SERVICE_NAME = "orders-worker"
     MW_TARGET = "https://<ACCOUNT-UID>.middleware.io"
  
     # Per-environment overrides
     [env.staging.vars]
     SERVICE_NAME = "orders-worker-staging"
  
     [env.production.vars]
     SERVICE_NAME = "orders-worker"

• Set your API key as a secret:
  js

  wrangler secret put MW_API_KEY
     # optionally per-env:
     wrangler secret put MW_API_KEY --env production

• Then read from env in your Worker:
  js

  init({
     serviceName: env.SERVICE_NAME,
     accountKey: env.MW_API_KEY, // bound secret
     target: env.MW_TARGET,
     consoleLogEnabled: false,
  });

6. View your data#

After deployment, give it 3–5 minutes, then open Middleware to see:

• Traces (incoming Worker requests, plus any upstream calls done via sdk.fetch)
• Logs (from sdk.logger.*)
• Profiling is not yet available for Cloudflare Workers in Middleware.

7. Environment variables#

(Names/usage align with the Middleware Worker agent options.) (docs.middleware.io, npm)

8. Troubleshooting#

• No traces/logs:
  • Confirm init(...) is called and track(request, ctx) wraps every request.
  • Check that accountKey/target are set (or bound via env).
• Upstream service not showing as a child span:
  • Use sdk.fetch(...) instead of fetch(...) to propagate context.
• Local dev secrets:
  • Use wrangler secret put for real secrets and .dev.vars for local-only values.
• Multiple environments:
  • Define vars per environment in wrangler.toml ([env.staging], [env.production]).