feat: game lobby service

lobby/internal/logging/context.go

@@ -0,0 +1,43 @@
+package logging
+
+import "context"
+
+// requestIDKey is the unexported context key under which the HTTP layer
+// stores the request id propagated from the X-Request-Id header.
+type requestIDKey struct{}
+
+// WithRequestID returns a child context that carries requestID. An empty
+// requestID returns ctx unchanged so callers do not have to branch.
+func WithRequestID(ctx context.Context, requestID string) context.Context {
+	if ctx == nil || requestID == "" {
+		return ctx
+	}
+	return context.WithValue(ctx, requestIDKey{}, requestID)
+}
+
+// RequestIDFromContext returns the request id stored on ctx by
+// WithRequestID, or an empty string when no value is present.
+func RequestIDFromContext(ctx context.Context) string {
+	if ctx == nil {
+		return ""
+	}
+	value, _ := ctx.Value(requestIDKey{}).(string)
+	return value
+}
+
+// ContextAttrs returns slog key-value pairs that materialise the frozen
+// `lobby/README.md` §Observability log fields `request_id`, `trace_id`,
+// and `span_id` from ctx. Pairs whose value is empty are omitted so logs
+// stay tight.
+func ContextAttrs(ctx context.Context) []any {
+	if ctx == nil {
+		return nil
+	}
+
+	var attrs []any
+	if requestID := RequestIDFromContext(ctx); requestID != "" {
+		attrs = append(attrs, "request_id", requestID)
+	}
+	attrs = append(attrs, TraceAttrsFromContext(ctx)...)
+	return attrs
+}