Leanpub production requires a particular file and folder structure:

1. manuscript folder which includes a book.txt for chapters.
2. images or resources folder (depending on markup format choice) inside the manuscript folder.

Besides the images folder, the rest of the folders are git submodules, ie pointers to other repos:

git submodule update --remote --merge

The git submodule is a pointer to another repo and is (currently) not recognised by Leanpub, so we need an actual copy of the images repo inside this repo, which is done with git subtree:

git pull -s subtree images master

lua filters and workflow are adapted from the kallipos repo: documentation for lua filters