By default, the package will start traces in every request handled by your Laravel app. In production, you'll likely don't want this as it might hurt performance a little.
Instead of measuring every request, you can measure only a small portion of requests using a sampler. A sampler is a class that determines which requests should be measured. By default, the package uses the Spatie\OpenTelemetry\Support\Samplers\AlwaysSampler sampler. This can be configured using the sampler key of the open-telemetry.php config file.
If you don't want to measure every request, you can use the Spatie\OpenTelemetry\Support\Samplers\LotterySampler that ships with the package. This sampler will measure performance for roughly every 2 out of 100 requests. To use this sampler, simply specify its class name the sampler key of the open-telemetry.php config file.
##Creating your own sampler
A sampler is any class that extends Spatie\OpenTelemetry\Support\Samplers. This abstract class requires you to implement a method shouldSample that should return a boolean. Here's an example where we create a CustomLotterySampler that will measure performance for roughly every 5 out of 1000 requests.
namespace App\Support\Samplers;
use Illuminate\Support\Lottery;
class LotterySampler extends Sampler
{
public function shouldSample(): bool
{
return Lottery::odds(5, 1000)->choose();
}
}
After creating your sampler, don't forget to put it's class name in the sampler key of the open-telemetry.php config file.