includeTraceContext is always set to true despite override about otel-cf-workers

[evanderkoogh]

I would love PRs. I am really looking to make this a project that can work even when I don’t have as much time to work on.

It is too important for the ecosystem to let things slip 😉

[rtbenfield]

Awesome! I can also share my use case here in case anyone comes across this issue with a similar one.

We have a Worker that receives an HTTP request generated by our users. That HTTP request may have a traceparent header from their app's instrumentation. We then do some work with that request and forward it to another system, but need to preserve the original traceparent value that we received. We use otel-cf-workers to capture traces from within our Worker, but need to essentially disable the context tracking from external requests in or out. The automatic instrumentation is currently overriding the traceparent of the outbound request.

With #24, we will be able to either disable the outbound trace context completely or intelligently with a snippet like:

const config: ResolveConfigFn = (env: Env, trigger) => {
  return {
    exporter: {
      // ...
    },
    fetch: {
      includeTraceContext(request) {
        // disable context propagation if the request has an existing traceparent
        return !request.headers.has("traceparent");
      }
    },
    service: {
      // ...
    },
  }
}

[evanderkoogh]

Thanks for the PR.. that is greatly appreciated :)