Koch E., Eisenbarth T. Growing Rails Applications in Practice (2014)

In this book we demonstrate low-ceremony techniques to scale large, monolithic Rails applications.
Instead of introducing new patterns or service-oriented architecture, we will show how to use
discipline, consistency and code organization to make your code grow more gently. Instead of using
new gems we will use the tools built into Rails to accomplish our goal. The tools you already know
and love.