Release prep: 54 engines, self-hosted signatures, i18n, dashboard updates

internal/infrastructure/tracing/middleware.go

@@ -0,0 +1,83 @@
+package tracing
+
+import (
+	"fmt"
+	"net/http"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// HTTPMiddleware creates spans for each HTTP request.
+// Extracts trace context from incoming headers and sets span attributes.
+func HTTPMiddleware(next http.Handler) http.Handler {
+	tracer := otel.Tracer("sentinel-soc/http")
+	propagator := otel.GetTextMapPropagator()
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Extract trace context from incoming headers.
+		ctx := propagator.Extract(r.Context(), propagation.HeaderCarrier(r.Header))
+
+		spanName := fmt.Sprintf("%s %s", r.Method, r.URL.Path)
+		ctx, span := tracer.Start(ctx, spanName,
+			trace.WithSpanKind(trace.SpanKindServer),
+			trace.WithAttributes(
+				attribute.String("http.method", r.Method),
+				attribute.String("http.url", r.URL.String()),
+				attribute.String("http.target", r.URL.Path),
+				attribute.String("http.user_agent", r.UserAgent()),
+				attribute.String("net.host.name", r.Host),
+			),
+		)
+		defer span.End()
+
+		// Wrap response writer to capture status code.
+		sw := &statusWriter{ResponseWriter: w, status: http.StatusOK}
+		next.ServeHTTP(sw, r.WithContext(ctx))
+
+		span.SetAttributes(
+			attribute.Int("http.status_code", sw.status),
+		)
+		if sw.status >= 400 {
+			span.SetAttributes(attribute.Bool("error", true))
+		}
+	})
+}
+
+// statusWriter captures the HTTP status code for span attributes.
+// Implements http.Flusher to support SSE/streaming through middleware chain.
+type statusWriter struct {
+	http.ResponseWriter
+	status      int
+	wroteHeader bool
+}
+
+func (sw *statusWriter) WriteHeader(code int) {
+	if !sw.wroteHeader {
+		sw.status = code
+		sw.wroteHeader = true
+	}
+	sw.ResponseWriter.WriteHeader(code)
+}
+
+func (sw *statusWriter) Write(b []byte) (int, error) {
+	if !sw.wroteHeader {
+		sw.wroteHeader = true
+	}
+	return sw.ResponseWriter.Write(b)
+}
+
+// Flush delegates to the underlying ResponseWriter if it supports http.Flusher.
+// Required for SSE streaming endpoints to work through the middleware chain.
+func (sw *statusWriter) Flush() {
+	if f, ok := sw.ResponseWriter.(http.Flusher); ok {
+		f.Flush()
+	}
+}
+
+// Unwrap returns the underlying ResponseWriter for Go 1.20+ ResponseController.
+func (sw *statusWriter) Unwrap() http.ResponseWriter {
+	return sw.ResponseWriter
+}