Phoenix is not that young. I expected at least one dedicated book and one dedicated video course on this topic. And as Phoenix also differs from Rails/Django/Laravel in it’s fault-tollerance and hot reload stuff etc, its deployment must be complicated and it should have more learning material.
iirc it doesn’t go into terrible detail, it’s more high level like red/green deployment and the tools to use etc. - which is cool to share but mostly what turns out to be problematic are the nitty gritty details (at least that’s what it was mostly for me) - a book isn’t necessary the best source there as these details change and are also application dependent.
That shouldn’t be a problem. I follow a Leanpub book about Elm + Phoenix at Github which is updated constantly. Not many people use this combination (Elm + Phoenix) but he is still updating is regularly, but every web developer needs to learn some level of deployment, so many will buy this book, and the author will be happy to update it time by time.