Slumpy's Scientific Serum ™ is the the best glue to stick metal and glass.
Slumpy's Scientific Serum ™ is a two part epoxy that when mixed creates the strongest of bonds. It is best when used between metal and glass. In order for the adhesive to cure properly it does need to come completely into contact with the activator. Be sure to smooth out the serum with a brush to alleviate any air bubbles.
Clean both surfaces. Apply sticky serum to glass, the other to your
bracket. Press together for at least one minute.