Log context on Workers

On Cloudflare Workers, deferred work started with waitUntil runs after the response closes. By then the request’s log context is gone, so logs from that work lose requestId, method, and URL fields.

Snapshot the context while the handler is still live, then re-enter it inside the deferred callback.

Steps

1. Call captureLogStore() inside the handler before returning the response.
2. Wrap the deferred callback in runWithLogStore(store, () => { ... }).
3. Pass the resulting promise to waitUntil from cloudflare:workers.

import {
  FlareHost,
  FlareResponse,
  captureLogStore,
  runWithLogStore,
} from "@flare-ts/core";
import { cf } from "@flare-ts/core/cloudflare";
import { waitUntil } from "cloudflare:workers";

const host = new FlareHost(cf);

host.http.get("/reports", (ctx) => {
  const store = captureLogStore();

  waitUntil(
    runWithLogStore(store, async () => {
      host.logger.info("report started", { path: ctx.req.path });
      // slow work after the response
      host.logger.info("report finished");
    }),
  );

  return new FlareResponse(202, { queued: true });
});

const app = host.build();
export default app.export();

When store is undefined (for example log.enableContext is off), runWithLogStore runs the callback without entering a store. The call is safe either way.

Why this is Workers-only

On Node the request keeps running in the same process, so log context follows async work without an extra step. See Logging for how context propagation works during normal request handling.

Related

• Context and waitUntil: deeper lifecycle notes
• Cloudflare overview: nodejs_compat requirement
• Deploy: worker entrypoint