observe

import "github.com/danmestas/dagnats/observe"

OpenTelemetry setup and trace-context propagation for DagNats processes. The engine, workers and bridge use the global OpenTelemetry providers; this package installs real ones and carries trace context across NATS messages.

Key Functions

Function	Description
`InitTelemetry(ctx, cfg)`	Creates and registers the tracer, meter and logger providers, exporting spans, metrics and logs to NATS JetStream and, when `OTLPEndpoint` is set, over OTLP/HTTP. Returns a shutdown function.
`EnsureDefaultPropagator()`	Installs the W3C trace-context and baggage propagator unless one is already set
`InjectTraceContext`, `InjectTraceContextHeader`	Write trace context into an event and NATS headers
`ExtractTraceContext`, `ExtractTraceContextHeader`, `ExtractTraceContextRaw`	Rebuild a context from a NATS message or headers
`TraceContextFromTask(task)`	Rebuild a context from a `protocol.TaskPayload` (its `traceparent` and `tracestate`)

Config

Field	Description
`ServiceName`	Required. Identifies the process in telemetry data.
`NATSConn`	Required. Connection used for the NATS-backed exporters. The caller owns it.
`OTLPEndpoint`	When non-empty, turns on OTLP export. The endpoint, headers and protocol come from the standard `OTEL_EXPORTER_OTLP_*` environment variables.
`Resource`	Extra resource attributes

InitTelemetry panics if NATSConn is nil or ServiceName is empty.

Usage

shutdown, err := observe.InitTelemetry(ctx, observe.Config{
    ServiceName: "my-worker",
    NATSConn:    nc,
})
if err != nil {
    log.Fatal(err)
}
defer shutdown(context.Background())

w := worker.NewWorker(nc)

Workers need no telemetry argument. Once InitTelemetry has run, they pick up the global providers.