Error: http: superfluous response.WriteHeader call

[bachgarash]

Description

Hi there. We have Kubernetes cluster where we run Datadog agent and exporting traces via Opentelemetry SDK manual instrumentated. I get a lot of errors

textPayload: "2025/01/20 04:50:21 http: superfluous response.WriteHeader call from go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp/internal/request.(*RespWriterWrapper).writeHeader (resp_writer_wrapper.go:78)"

Environment

• OS: Linux
• Architecture: x86
• Go Version: 1.23
• go.opentelemetry.io/contrib version: v0.20.0
• Datadog agent version : v7.60.0

Steps To Reproduce

1. Using this code ...

func (th TracingHelpers) WithHTTPTraceMetadata() func(handler http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(
			func(w http.ResponseWriter, r *http.Request) {
				span := oteltrace.SpanFromContext(r.Context())
				if span.IsRecording() {
					// Add standard attributes
					span.SetAttributes(
						tracing.Attach("env", th.environment),
					)

					// Set trace context header
					spanCtx := span.SpanContext()
					if spanCtx.IsValid() && spanCtx.IsSampled() {
						traceHeader := spanCtx.TraceID().String()
						w.Header().Set("X-custom-header", traceHeader)
					}
				}
				next.ServeHTTP(w, r)
			})
	}
}

2. Run ...
3. See error ...

Expected behavior

A clear and concise description of what you expected to happen.

Datadog agent pod is logging a lot of these errors

textPayload: "2025/01/20 04:50:21 http: superfluous response.WriteHeader call from go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp/internal/request.(*RespWriterWrapper).writeHeader (resp_writer_wrapper.go:78)"

[dmathieu]

You're using a very old version of the contrib package. This issue has been fixed some time ago.
See #6055

[bachgarash]

Thanks for quick reply. But I am having hard time to understand this version scheme.

[dmathieu]

That is because there are multiple packages with different versions, but they're all released at the same time.
The otlelhttp package's latest version is 0.59.0. You can see that here: https://pkg.go.dev/go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp