Clean Architectures in Python: A Practical approach to Better Software Design. 2 Ed

Table of Contents
Introduction
What is a software architecture?
Why is it called ``clean''?
Why ``architectures''?
Why Python?
Acknowledgments
About the book
Prerequisites and structure of the book
Typographic conventions
Why this book comes for free
Submitting issues or patches
About the author
Changes in the second edition
Chapter 01 A day in the life of a clean system
The data flow
Advantages of a layered architecture
Chapter 02 Components of a clean architecture
Chapter 03 A basic example
Chapter 04 Add a web application
Flask setup
Test and create an HTTP endpoint
WSGI
Chapter 05 Error management
Request and responses
Basic structure
Requests and responses in a use case
Request validation
Responses and failures
Error management in a use case
Integrating external systems
Chapter 06 Integration with a real external system postgres
Decoupling with interfaces
A repository based on PostgreSQL
Label integration tests
Create SQLAlchemy classes
Orchestration management
Database fixtures
Integration tests
Chapter 07 Integration with a real external system mongodb
Fixtures
Docker Compose configuration
Application configuration
Integration tests
The MongoDB repository
Chapter 08 Run a production ready system
Build a web stack
Connect to a production-ready database
Changelog
Colophon

The clean architecture is the opposite of spaghetti code, where everything is interlaced and there are no single elements that can be easily detached from the rest and replaced without the whole system collapsing. The main point of the clean architecture is to make clear "what is where and why", and this should be your first concern while you design and implement a software system, whatever architecture or development methodology you want to follow.

To fully appreciate the book you need to know Python and be familiar with TDD, in particular with unit testing and mocks. Please refer to the series TDD in Python with pytest published on my blog if you need to refresh your knowledge about these topics.

After the two introductory parts that you are reading, chapter 1 goes through a 10,000 feet overview of a system designed with a clean architecture, while chapter 2 briefly discusses the components and the ideas behind this software architecture. Chapter 3 runs through a concrete example of clean architecture and chapter 4 expands the example adding a web application on top of it. Chapter 5 discusses error management and improvements to the Python code developed in the previous chapters. Chapters 6 and 7 show how to plug different database systems to the web service created previously, and chapter 8 wraps up the example showing how to run the application with a production-ready configuration.