How can I "attach" a red circle to a line when drag&drop?

Question

JavaScript

I use konvajs. You need to "attach" the red circle to the line, that is, this circle should move along the frame of the white rhombus along with the line.
I searched for articles on this topic, I did not find anything suitable. Tell me, maybe there is somewhere a ready-made similar option, or articles on this topic. Thanks