Architecture Decision RecordEdit
An Architecture Decision Record (ADR) is a lightweight, structured way for software teams to capture the rationale behind significant architectural choices. Each ADR documents a specific decision, the context that led to it, the options considered, and the consequences—both intended and unintended. The goal is to produce a durable, readable trail of reasoning that future teams can consult to understand why a path was chosen, how it aligns with project goals, and what trade-offs were accepted. ADRs are meant to complement diagrams and designs, not replace them, and they serve as a practical tool for accountability, onboarding, and long-term maintenance. For a broader frame, see software architecture.
Core concepts
Definition and purpose
An ADR records a decision about an architectural issue—such as selecting a persistence strategy, an integration approach, or a deployment model—and explains why that choice was made. The record typically covers the problem, the alternatives considered, the chosen option, and the consequences. In many teams, ADRs function as concise decision logs that stay relevant as systems evolve, helping current and future members understand how and why the system is structured as it is. See architecture governance for related governance concepts.
Typical structure
A standard ADR often follows a lightweight template, which may include: - Status (e.g., proposed, accepted, deprecated) - Context or problem statement - Decision (the chosen option) - Rationale (why this option was selected) - Alternatives considered - Consequences (positive and negative, including risks and edge cases) - Stakeholders and date - Related ADRs or decisions This modular format keeps each record focused and easy to reference in documentation.
Relationship to other artifacts
ADRs are designed to sit alongside architectural diagrams, design documents, and system models. They complement these artifacts by explaining why a particular structure or pattern was adopted, rather than merely describing what was built. ADRs can point to diagrams in architecture diagram repositories or to code-level considerations in a design document.
Typical topics
ADRs cover a wide range of architectural decisions, from technology choices (e.g., selecting a database or messaging system) to non-functional requirements (e.g., performance targets, reliability strategies) and governance aspects (e.g., deployment strategies, security controls). See risk management for how decisions tie into risk assessment, and regulatory compliance for decisions that affect auditability or privacy requirements.
Adoption in practice
Lightweight by design
Proponents emphasize keeping ADRs small and action-oriented. The cost of a heavy, bureaucratic process is often higher than the value gained, particularly in fast-moving teams. A pragmatic approach balances documentation with speed, avoiding over-ritualized processes that slow delivery. This aligns with lean software development principles and with the idea that the best documentation is the one that gets updated when decisions change. For more on efficient practices, see lean software development and agile software development.
Ownership and lifecycle
An ADR should have an owner who is responsible for maintaining it as the system evolves. Owners monitor for changes that would require updating the ADR or creating new records. Periodic reviews help ensure records stay accurate and relevant, preventing “dead” ADRs that mislead teams. See ownership and governance for related ideas.
Formats in use
Teams adopt templates suited to their culture and tooling. Some use file-based ADRs stored in a version-controlled documentation repository; others maintain lightweight notes in a wiki or a project management space. The essential point is consistency and discoverability, so team members can locate the relevant ADRs when decisions or trade-offs come into question.
Controversies and debates
When does a record become overhead?
Critics argue that ADRs can become bureaucratic if created for every small decision or treated as mandatory ceremony rather than a living forum for discourse. From a practical, center-oriented perspective, the best ADRs are those that document only decisions with meaningful long-term impact and that remain easy to read and update. Advocates respond that properly scoped ADRs prevent costly rework by preserving context and enabling informed re-evaluation later, especially as teams scale or as personnel rotate. See also risk management and documentation for how record-keeping relates to project health.
The risk of outdated records
A common concern is that ADRs can become stale or mismatched with the current system, leading teams to rely on past reasoning that no longer applies. The counterargument is that living ADRs—paired with regular reviews and a lightweight ownership model—keep records current and useful. This tension is a core part of debates about how formal the process should be and how often to revisit decisions, a topic that often plays out differently across organizations and project types.
ADRs versus other governance mechanisms
Some organizations favor formal architecture reviews or heavy governance boards, while others push for minimal documentation and decentralized decision-making. The middle ground—clear ownership, lightweight ADRs, and targeted governance—tends to deliver the benefits of traceability and accountability without dragging teams down. See architecture governance for related discussions about how decisions are surfaced and tracked.
Why some criticisms miss the point
Critics may frame ADRs as mere “office politics” or as tools to enforce conformity. Proponents counter that ADRs are practical mechanisms to reduce risk, improve onboarding, and preserve organizational knowledge beyond individual memory. They emphasize that ADRs should be focused on decisions that affect system shape, lifecycle costs, or regulatory concerns, not on micromanaging day-to-day tasks.
Practical guidance and best practices
- Keep ADRs brief and decision-focused; use a consistent template.
- Link ADRs to relevant artifacts (diagrams, design documents, or risk registers) to provide context without duplicating content.
- Assign an owner and establish a lightweight review cadence to keep records fresh.
- Treat ADRs as living documents: revise or deprecate records when decisions change or when new evidence emerges.
- Use ADRs to highlight trade-offs, so future teams can make informed choices without rehashing the entire debate.