Retrieve opentelemetry parent span from headers

[adam-cattermole]

The changes here use the propagated headers from wasm-shim to configure the current span for each incoming request to limitador.

Verification

I have provided a script in a branch of the kuadrant-operator that provisions and configures everything necessary for the tracing setup. This configures and deploys jaeger, istio, authorino as well as a route, authpolicy and ratelimitpolicy and limitador changes from this branch.

From my branch https://github.com/adam-cattermole/kuadrant-operator/tree/tracing-script

. hack/tracing-setup.sh

Then you can open the jaeger UI:

firefox -private-window "tracing.${INGRESS_DOMAIN}"

Look for the requests under Service: istio-ingressgateway-istio.istio-system -> Operation: egress api.toystore.com

Send a curl request to the endpoint providing the tracing headers:

curl -H 'Authorization: APIKEY IAMALICE' \
    -H 'Host: api.toystore.com' \
    -H "Traceparent: 00-$(openssl rand -hex 16)-00f067aa0ba902b7-01" \
    -H 'Tracestate: rojo=00f067aa0ba902b7' \
    -H 'Baggage: key1=value1;property1;property2, key2 = value2, key3=value3; propertyKey=propertyValue' \
    http://$GATEWAY_URL/cars

See the full trace:

[adam-cattermole]

Changed the name here to match authorino spans