Trace context lost for asynchronous requests about oneagent-sdk-for-nodejs HOT 2 CLOSED

It's not really a context loss here. This is a limitation of how request attributes are attached to a trace.

As of now request attributes can be only attached to an open request. Once you send the 202 response the web request trace entry is ended and as a result the request attribute can't be attached anymore.
In contrast to request attributes other children like DB, HTTP or messaging requests (even when done via SDK) create a new linked entry in the trace but that's currently not supported for request attributes.

However, request attributes can be attached to this children and they are propagated up to the web request. But again they have to be added when the request is still ongoing.

Here is a small sample to illustrate this:

import * as http from "http";
import { createInstance } from "@dynatrace/oneagent-sdk";

const sdk = createInstance();
sdk.setLoggingCallbacks({
  error(msg) { console.log("sdk error:", msg) },
  warning(msg) { console.log("sdk warn:", msg) }
});

http.createServer((req, res) => {
  sdk.addCustomRequestAttribute("onRequest", "works");
  res.statusCode = 202;
  res.end();
  sdk.addCustomRequestAttribute("afterEnd sync in handler", "works");

  setImmediate(() => {
    sdk.addCustomRequestAttribute("afterEnd async", "works not");

    http.get("http://example.org", (cltRsp) => {
      cltRsp.resume();
      sdk.addCustomRequestAttribute("inCltCb", "works again as in a sync callback");
    });
  });
}).listen(8100);

The SDK log attribute <afterEnd async> not added because no active trace context found is a bit misleading here. A better wording would be probably attribute <afterEnd async> not added because no transaction is active.

fyi @z1c0

from oneagent-sdk-for-nodejs.

I will close this issue. Feel free to reopen in case you have more questions regarding this.

from oneagent-sdk-for-nodejs.