Using Architecture Decision Records (ADRs): A Practical Guide for IT Architects

In complex IT systems, decisions about architecture shape the project’s long-term success. However, without proper documentation, these decisions can become “tribal knowledge” — known only to a few team members and easily lost over time.

Architecture Decision Records (ADRs) solve this problem by providing a lightweight, structured way to capture the context, reasoning, and outcome behind every significant architecture decision.

1. What is an Architecture Decision Record (ADR)?

An ADR is a short document that records an important architecture decision made during the project lifecycle, along with:

• Context – Why the decision was needed.
• Decision – The actual choice made.
• Consequences – Positive and negative impacts of the decision.
• Alternatives considered – Other options and why they were rejected.

It acts as a single source of truth for the why behind architectural choices, enabling clarity and alignment for the entire team.

2. Why ADRs are Important

2.1 Maintain Project Knowledge

Architects and developers come and go, but ADRs keep the decision history alive.

2.2 Support Governance & Compliance

Regulated industries like banking, healthcare, and finance require auditable records of decision-making.

2.3 Facilitate Collaboration

ADRs make it easier for cross-functional teams (developers, business analysts, operations, security) to align.

2.4 Reduce Decision Rework

By reviewing past ADRs, teams can avoid revisiting the same debates unnecessarily.

4. When to Use ADRs

ADRs should be created for significant architectural decisions, such as:

• Choosing a microservices vs. monolithic architecture.
• Selecting a cloud provider (AWS, Azure, GCP).
• Deciding on security protocols or data encryption standards.
• Choosing between SQL vs. NoSQL databases.
• Adopting specific API strategies (REST, GraphQL, gRPC).

5. ADR Structure (Template)

A common lightweight ADR template looks like this:

# ADR-001: Database Technology for Payment Service

## Status
Accepted | Proposed | Deprecated | Superseded

## Context
Our payment service must support high transaction throughput, strong consistency, and ACID compliance...

## Decision
We will use PostgreSQL 15 with a high-availability cluster setup...

## Consequences
+ Strong relational integrity and transaction guarantees.
- More complex scaling for read-heavy workloads.

## Alternatives Considered
- MySQL: Lacked certain JSON features we require.
- MongoDB: Document store model not ideal for transactional workloads.

6. Best Practices for ADRs

1. Keep it short – 1–2 pages per decision.
2. Use consistent naming – e.g., ADR-001, ADR-002.
3. Link to related artifacts – diagrams, requirement docs, code repos.
4. Record decisions as soon as possible – while context is fresh.
5. Version control your ADRs – store them in Git alongside the source code.
6. Mark outdated decisions – use “Superseded” status when a new ADR replaces an old one.

7. Tools & Automation

Modern teams use tools like:

• Markdown files in Git – simplest and most version-control friendly.
• adr-tools – CLI tool for managing ADRs.
• Confluence templates – for teams using Atlassian stack.
• GitHub Wikis or GitLab Pages – easy web-based browsing of ADRs.

8. Conclusion

ADRs are not bureaucracy—they are the memory of your architecture. They ensure that future architects and developers understand not just what decisions were made, but why. By adopting ADRs as part of your architecture governance, you improve transparency, accountability, and project resilience.