I get why rasterio is preferred, its API is less annoying, but I'm not sure putting a leaking abstraction over gdal helps much. It just creates an aluring veneer over gdal, without really solving the main problems of gdal, being its monolithic monstrosity of hardly portable yet highly necessary GIS tool functionality.
Doesn't matter too much with gdal's warts, as this server should be deployed with ansible or in a container anyways, so portability is handled in a somewhat sane manner.
Thanks for open sourcing this!