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Documentation Principles

Overview

Our documentation principles revolves around two key themes:

  • Document your architecture using C4.
  • Document decisions via ADRs (Architecture Decision Records).

This approach ensures a clear, structured, and maintainable record of both the current state of the system and the rationale behind critical decisions.

Principles

Document Your Architecture Using C4

The C4 Model provides a simple yet powerful way to visualize software architecture at different levels of abstraction:

  1. Context: Show how the system interacts with users and other systems.
  2. Container: Break down the system into individual applications or services.
  3. Component: Dive deeper into the internal structure of each container.
  4. Code: Provide optional, detailed views of the source code when needed.

In most cases, we only need to focus on Context and Container diagrams. This approach provides a shared language for technical and non-technical stakeholders, ensuring clear communication across teams and the broader business.

Document Decisions via ADRs

Architecture Decision Records capture the rationale behind significant architectural choices in a lightweight, accessible format. They help teams:

  • Understand why decisions were made, even years later.
  • Share context with new team members.
  • Avoid rehashing previous discussions or repeating mistakes.

We use Michael Nygard's ADR template for consistency and clarity.

ADR Structure:

  • Title: A clear and concise name for the decision.
  • Context: The background and factors influencing the decision.
  • Decision: What was decided and why.
  • Consequences: The positive and negative effects of the decision.

Guidelines

C4 Documentation Guidelines

  1. Start Simple: Begin with the Context diagram to provide a high-level overview. Add details incrementally.
  2. Focus on Key Components: Prioritize documenting areas of high complexity or importance.
  3. Use Standard Notation: Stick to consistent symbols and terminology for clarity.
  4. Update Regularly: Keep diagrams and documentation up-to-date with system changes.

ADR Best Practices

  1. Keep It Lightweight: Focus on clarity and conciseness. Avoid unnecessary verbosity.
  2. Capture Key Decisions: Document only decisions that have significant technical or organizational impact.
  3. Be Transparent: Include trade-offs and dissenting opinions where relevant.
  4. Link to Related Resources: Reference relevant diagrams, tickets, or discussions to provide additional context.

Summary

Our primary focus is on maintaining clarity and traceability through architecture diagrams and decision records. The combination of C4 and ADRs provides a scalable and effective way to document both the system’s structure and the reasoning behind its evolution.

Further Reading