Auto hook-up with downstream HTTP client requests?

[icelava]

I tested using Laravel's recommended Guzzle HTTP client request pattern to a traced back-end API tier. It does not look like the trace ID in Laravel is being handed down to the back-end.

use App\Http\Controllers\Controller;
use Illuminate\Support\Facades\Http;
use Napp\Xray\Facades\Xray;

class XRayController extends Controller
{
    public function trace()
    {
		Xray::addSegment('XRayController');

		// HTTP call to back-end tier.
		$apiUrl = "http://localhost:8081/api/Tier";
		$response = Http::get($apiUrl);
		$delayTime = $response->body();

		Xray::endSegment('XRayController');
      
		return view('traceapi', ['timing' => $delayTime]);
    }
}

Where can the client get the trace ID to forward into the X-Amzn-Trace-Id header?

[icelava]

Perusing the libraries' code I think I know how to extract the trace ID from the underlying trace/segment object.

    public function trace()
    {
		$selfSegment = 'XRayController';
		$backendSegment = 'XRayBackApi';
		Xray::addSegment($selfSegment);

		// HTTP call to back-end tier.
		$xrayHeader = "X-Amzn-Trace-Id";
		$traceId = Xray::tracer()->getTraceId();
		$traceIdString = "Root=" . $traceId . ";Sampled=1";

		$apiUrl = "http://localhost:8081/api/Tier";

		Xray::addSegment($backendSegment );
		$response = Http::withHeaders([
			$xrayHeader => $traceIdString
		])->get($apiUrl);
		Xray::endSegment($backendSegment );
		$delayTime = $response->body();

		Xray::endSegment($selfSegment);

		return view('traceapi', ['timing' => $delayTime]);
    }

While the traces now show the correlated tiers together, the service map nodes are not shown to be linked though.

[icelava]

Based on Patrick Kerrigan's advice, applied current app's segment ID as parent ID for the back-end tier.

Xray::addSegment($selfSegment);

$xrayHeader = "X-Amzn-Trace-Id";
$traceId = Xray::tracer()->getTraceId();
$selfSegmentId = Xray::current()->getId();
// Hard-coded smapling rate for now.
$samplingRate = 1;
$traceIdString = "Root=" . $traceId . ";Parent=" . $selfSegmentId . ";Sampled=" . $samplingRate;
$apiUrl = "http://localhost:8081/api/Tier";

$response = Http::withHeaders([
	$xrayHeader => $traceIdString
])->get($apiUrl);
$delayTime = $response->body();

Xray::endSegment($selfSegment);
return view('traceapi', ['timing' => $delayTime]);

The X-Ray service map can then tie together the service node tiers.