A good question today about the railings and lighting the perimeter with “mood” lighting. It’s dark out, you want to see the edge of the decking and have a boundary fixed for your party or dinner outside. Some railing systems now can insert lights inside the columns or rails and work from a dedicated circuit for the lighting, looks good and usually expensive. A very simple comment back to me suggested we use rope lighting. along the upper rail, underneath and situated along the outside so it is hidden from view. Certainly no drilling into the rails or need for an electrician to do the hard wiring.
Just a suggestion and something to consider which is faster and easier.