There is no book cover image to put on Hacker Shelf.
A simple and plain version of the red, white, and black header of the site, with the author’s name written beneath it, and arranged in an image with a portrait layout, would be enough. Or you can add whatever graphics you think fit the book.
Add book cover, fixes #11; regenerate assets
Boom! Finally had a bit of time to create a basic book cover: https://github.com/mixu/distsysbook/blob/master/output/images/dist-sys-cover.png
I'll see if I can update the book profile on Hacker Shelf.
Thanks for suggesting this!