opentelgrpc

opentelgrpc adds OpenTelemetry spans, trace context propagation, and rpc.server and rpc.client metrics to gRPC servers and clients.

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Table of contents

Part of nurago, a collection of independent Go packages for backend services.

import "github.com/tecnickcom/nurago/pkg/metrics/opentel/opentelgrpc"

OpenTelemetry tracing and metrics for grpcserver and grpcclient, built on the otelgrpc stats handlers.

in, err := opentelgrpc.New()

grpcserver.WithInstrumenter(in)
grpcclient.WithInstrumenter(in)

No further wiring after opentel

With no options, the global tracer, meter and propagator providers are used, and opentel installs those in New. A service that already exports HTTP telemetry through opentel gets gRPC spans and metrics on the same exporters, with the same resource attributes, by adding one option to each side.

WithTracerProvider, WithMeterProvider and WithPropagators set explicit providers, which is what a test uses to capture spans without touching global state.

What it produces

  • A span for every RPC, on both sides, with trace context propagated through the request metadata. A trace that starts at an HTTP handler continues across the gRPC call and into the downstream service.
  • The rpc.server.* and rpc.client.* metrics of the OpenTelemetry semantic conventions.

It uses stats handlers rather than interceptors, as otelgrpc recommends: they see transport events, such as message sizes and the end of a stream, that interceptors do not.

Health and reflection are filtered out

By default grpc.health.v1.Health and grpc.reflection.* RPCs produce neither spans nor metrics. A probe every few seconds per instance would otherwise fill the trace backend with traces nobody reads, and on a sampled backend crowd out the ones that matter. WithFilter adds filters; WithoutDefaultFilter removes the default one.

Dependencies

Reaches otelgrpc, the OpenTelemetry API modules and google.golang.org/grpc: 15 external modules in total. The SDK and exporters come from opentel.