Ethern

> Sure, though I would go straight to Open Telemetry. @mattklein123 Have a question in mind: if we are going to send out OTEL span when calling memcached and redis,...

> Yeah we can add this to the API for sure. Nice, then let me finish the implementation from ratelimit side first

I think I can work on adding Prometheus instrumentation in ratelimit, but I believe we should work out a list of possible metric to be implemented first.

/remove-lifecycle rotten

I double-checked the standard [Istio metrics list](https://istio.io/latest/docs/reference/config/metrics/), it only contains the TCP metrics listed above. Also the [Grafana Istio dashboard](https://grafana.com/grafana/dashboards/7636) needs to use the metric istio_tcp_received_bytes_total and istio_tcp_sent_bytes_total. I think...