Architecture as Code · Whitepaper

Chapter 4 · Foundations

Architecture Decision Records (ADR)

Key insights from Chapter 4 of "Architecture as Code"

Author Gunnar Nordqvist
Published 23 October 2025
Build number 2025.10
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ADR Process Flow
ADR Process Flow

The Architecture as Code methodology forms the foundation for Architecture Decision Records (ADR), which provide a systematic approach for documenting important architecture decisions that affect system structure, performance, security, and maintainability. The ADR method was introduced by Michael Nygard (2011) Source [39] and has become an established best practice in modern system development.

For organisations implementing Architecture as Code, ADRs are particularly valuable because they ensure architecture decisions are documented in a structured manner that meets compliance requirements and facilitates knowledge transfer between teams and over time.

ADRs function as architecture's "commit messages"—short, focused documents that capture the context, the problem, the chosen alternative, and the consequences of important architecture decisions. This enables traceability and an understanding of why specific technical choices were made.

Primary topics explored

  1. Overall Description
  2. What Are Architecture Decision Records?
  3. Structure and Components of ADR
  4. Practical Examples of ADR
  5. Tools and Best Practices for ADR within Architecture as Code
  6. Integration with Architecture as Code

About Architecture as Code

Infrastructure as Code represents a fundamental change in how we manage and develop IT infrastructure. This book provides organisations with practical guidance for implementing IaC principles whilst fulfilling local compliance requirements and optimising costs.

The book covers everything from fundamental principles and tools to advanced implementation strategies, security aspects, and organisational changes required for successful IaC adoption.

Who should read this

IT architects, DevOps teams, developers, and decision-makers within organisations.

Portrait of Gunnar Nordqvist

Gunnar Nordqvist

Conceived, directed and published the books of The Transformed Architecture.

Continue with the full chapter

Read the full chapter online

Chapter 4: Architecture Decision Records (ADR) in Architecture as Code gives the detailed explanations, practical examples and implementation patterns behind this summary.

This whitepaper belongs to “Foundations” and is one of 38 drawn from the manuscript.