title: Nginx: how to generate X-B3-SpanId 16 random bytes for tracing
body: <p>I'm trying to generate zipkin trace id from nginx in order to be able to trace from nginx to applications. To achieve this, I want to find out how to generate 16 random bytes to be used for X-B3-SpanId since $request_id generates 32 bytes (which can be used for X-B3-TraceId).</p>