Is there a way to get latency introduced by name resolution, TCP connection and TLS handshake, while the channel is in Connecting state

[golthitarun]

Hi,

Trying to figure out if there is any way to record metrics with the latency introduced by name resolution, TCP connection and TLS handshake while the channel is in connecting state.

[kannanjgithub]

Latency for name resolution and for the remainder of the connection establishment can be done with OpenTelemetry tracing. These measurements aren't great for metrics because so few RPCs will see those latencies.

NAME_RESOLUTION_DELAYED stores one part of it. The other part can be recorded by a ClientStreamTracer as the time between createPendingStream() and streamCreated().

Tracing is disabled by default, so you'd need to set GRPC_EXPERIMENTAL_ENABLE_OTEL_TRACING=true (which we have documented) . To use your own tracer that does the latency measurement above, you'd need an interceptor to do callOptions.withStreamTracerFactory(). That method isn't available on AbstractStub.

The other option is OpenCensus (which does similar).