Read it here.

Introduction

Needless to say, the Redis project is quite a success. It’s an
important component in backend applications.

Redis could be considered one of the building blocks of
modern computing. There are not many projects that fit the such role and
stood the test of time. Here are some examples that meet my criteria of
the “building block”: NGINX, SQLite, PostgreSQL, Kafka, Linux kernel,
etc.

Most of us are not working on projects of such a level, but it is
still worthwhile to learn from those projects. It takes higher skill and
deeper knowledge to build such projects, thus learning from those
projects could be a path to the next level as a software developer. The
book is the result of my own learning.

Why a Book?

My motivations for writing this book:

• Thanks to the open-source culture, anyone can learn from those
  projects freely by reading the source code. One of my motivations for
  writing the book is to share what I have learned in the past, and my
  book is freely available on the web as a giving back. (You can still
  purchase ebooks or paperbacks.)
• Like most real-world projects, Redis is a complex project built with
  lots of effort, which can be hard to grasp for beginners. Instead, my
  book takes an opposite approach: learning by building things from
  scratch; there are not many “from scratch” books.