Calibre Server on Linux
Calibre is a powerful cross-platform, open source, ebook manager and editing platform. Its calibre-server component can be used to publish an e-book library on a local network. While you can launch calibre-server as a desktop application, it can also be run as a daemon on a headless Linux server.
This tutorial on setting up calibre-server using Ubuntu 14.04 is very good, but dated.