Hmmm ok. Momentary snag! 
Thank you for the heads-up @riking.
AWS S3 has a feature where if you name the bucket the same as the domain, it easily lets you just add a CNAME record to the domain and it just all works.
So now I’m searching everywhere for info on how to attach a domain to a bucket that does not have the same name as the domain… hmm
@BryanV how did you point https://discourse-uploads.bokeh.org to your S3 bucket?