Function init_telemetry_with_sampler 

pub fn init_telemetry_with_sampler(
    service_name: &str,
    sampler: Option<TraceSampler>,
) -> Result<TelemetryHandles, Box<dyn Error>>

Initialise OpenTelemetry traces + metrics with OTLP gRPC export and an explicit trace sampler.

Convenience wrapper around Telemetry::builder. When sampler is None, falls back to OTEL_TRACES_SAMPLER / OTEL_TRACES_SAMPLER_ARG, then always-on.

Example

use otel_bootstrap::TraceSampler;
let sampler = TraceSampler::ParentBased(Box::new(TraceSampler::TraceIdRatio(0.1)));
let _tel = otel_bootstrap::init_telemetry_with_sampler("my-service", Some(sampler))?;