Gluing metal and glass pieces of a lamp (Artemide Demetra)
I would repair this by using a flexible adhesive called E6000. This is advertised to be a strong adhesive for both metal and glass.



(Picture source at Amazon Product Page)

The flexible nature of this adhesive means that it will provide some isolation between the glass part and the metal posts. Before using make sure to do a very good job of removing any old glue debris, paint or finger oils. Rubbing alcohol and Q-Tip swabs are my go-to tools for the final cleaning phase.

The E6000 adhesive can bridge a small gap but it also has a tendency to spread itself out around the site where it is applied so make sure to keep you glass plate flat (horizontal) when you set it in place on the posts. This adhesive will hold on tight to non-porous materials and yet remain peel-able for removal. I have even used it to glue magnets to the covers of white board markers so I could stick the markers to the surface of a metal white board.