I have made several bird houses and have done some reading on building them and I have learned......
Most birds don't like the perches at the door. It leaves a place for larger birds to sit and wait for them to come and go and wait for the hatchlings to take their first flight.
Venting is a must to keep the temp cooler inside. The adult birds keep the eggs warm enough and they need to breath fresh air. (in your case a few small holes around the outside of the upper edge of the keg would help alot)
Most birds do not like bright colors on their houses. This is something that people think is cute, birds not so much. And they don't care for the smell of fresh paint either.
Birds do not really like new wood either. Usually it takes me about 8 months to a year before they think the "new" house is weathered and secure enough to live in.
I am assuming that the keg you used is aluminium and while I'm not sure how they will take to that, I do expect hat it will get quite hot in the summer sun so I might recommend central air conditioning for your house.
(Just joking)
I do like your idea and I think it is quite cute but, I think it will be more enjoyment to you and guests than the birds.
Good luck with getting a new family in the neighborhood.
Rog