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Architecture Decision Records (ADRs)

This directory contains Architecture Decision Records (ADRs) that document important architectural decisions made throughout GISE methodology projects. ADRs provide context, rationale, and consequences of technical choices to help teams understand and maintain architectural decisions over time.

What are ADRs?​

Architecture Decision Records are documents that capture an important architectural decision made along with its context and consequences. They help teams:

  • Understand the "why" behind architectural choices
  • Track decision evolution over time
  • Avoid repeating past discussions
  • Onboard new team members effectively
  • Learn from previous decisions

ADR Structure​

Each ADR follows a consistent structure:

  • Title: Clear, descriptive decision title
  • Status: Current status (Proposed, Accepted, Rejected, Deprecated, Superseded)
  • Context: Situation that motivates the decision
  • Decision: The choice that was made
  • Consequences: Results of the decision, both positive and negative

Using ADRs in GISE Projects​

When to Create an ADR​

Create an ADR when making decisions that:

  • Impact multiple teams or system components
  • Have long-term consequences for the system
  • Involve significant trade-offs between alternatives
  • Establish patterns that will be followed elsewhere
  • Require stakeholder buy-in or approval

ADR Lifecycle​

Integration with GISE Phases​

Discover Phase

  • Document architectural constraints and requirements
  • Record stakeholder preferences and non-functional requirements
  • Identify architecture-influencing factors

Design Phase

  • Create ADRs for major architectural decisions
  • Document technology choices and patterns
  • Record design trade-offs and alternatives considered

Develop Phase

  • Update ADRs based on implementation learnings
  • Document technical decisions that emerge during development
  • Record performance and scalability insights

Deploy Phase

  • Validate ADR assumptions against production behavior
  • Document operational decisions and deployment patterns
  • Plan reviews and updates for next iteration

ADR Categories​

System Architecture​

  • Overall system structure and boundaries
  • Architectural patterns (monolith, microservices, etc.)
  • Integration patterns and communication protocols
  • Scalability and performance architecture

Technology Choices​

  • Programming languages and frameworks
  • Database technologies and data storage
  • Infrastructure and deployment platforms
  • Third-party services and tools

Security Architecture​

  • Authentication and authorization patterns
  • Data protection and privacy measures
  • Security controls and compliance requirements
  • Threat modeling and risk mitigation

Quality Attributes​

  • Performance requirements and optimization strategies
  • Reliability and availability patterns
  • Maintainability and technical debt management
  • Testability and quality assurance approaches

ADR Templates​

Use these templates as starting points for your ADRs:

Basic ADR Template​

# ADR-[NUMBER]: [TITLE]

**Status**: [Proposed | Accepted | Rejected | Deprecated | Superseded]
**Date**: [YYYY-MM-DD]
**Authors**: [Name(s)]
**Reviewers**: [Name(s)]

## Context
[Describe the situation and forces at play]

## Decision
[State the architecture decision and rationale]

## Consequences
[Describe the resulting context and implications]

Detailed ADR Template​

For more complex decisions, use the comprehensive ADR template with sections for:

  • Context and problem statement
  • Considered alternatives with pros/cons
  • Decision rationale and implementation details
  • Positive, negative, and neutral consequences
  • Follow-up actions and success metrics

Best Practices​

Writing Effective ADRs​

  1. Be Specific: Include concrete technical details and examples
  2. Show Your Work: Document alternatives considered and evaluation criteria
  3. Think Long-term: Consider maintenance, evolution, and team changes
  4. Use Diagrams: Include architectural diagrams where helpful
  5. Reference Standards: Link to coding standards, best practices, and external resources

ADR Maintenance​

  1. Regular Reviews: Schedule quarterly reviews of active ADRs
  2. Status Updates: Keep ADR status current as decisions evolve
  3. Cross-References: Link related ADRs and update when superseding
  4. Archive Appropriately: Maintain historical record even for superseded decisions

Team Collaboration​

  1. Involve Stakeholders: Include relevant team members in ADR creation
  2. Review Process: Establish clear review and approval workflows
  3. Communication: Share ADR decisions with broader team
  4. Learning: Use ADRs for knowledge sharing and team education

Tools and Automation​

ADR Tools​

  • adr-tools: Command-line tools for creating and managing ADRs
  • Log4brains: Web UI for browsing and managing architectural decisions
  • Backstage: Developer portal integration for ADR discovery

Version Control Integration​

  • Store ADRs in Git alongside source code
  • Use pull request workflow for ADR review and approval
  • Automate ADR numbering and formatting
  • Generate ADR indexes and cross-references

Documentation Integration​

  • Include ADRs in project documentation sites
  • Generate architectural decision summaries
  • Create decision timelines and dependency graphs
  • Export ADRs for stakeholder reporting

Getting Started​

1. Setup ADR Structure​

Create ADR directory structure in your project:

docs/
├── architecture/
│   ├── decisions/
│   │   ├── 0001-record-architecture-decisions.md
│   │   ├── 0002-choose-database-technology.md
│   │   └── template.md
│   └── diagrams/

2. Create First ADR​

Document the decision to use ADRs:

# Using adr-tools
adr new "Record architecture decisions"

3. Establish Process​

  • Define when ADRs are required
  • Set up review and approval workflow
  • Train team on ADR creation and maintenance
  • Schedule regular ADR review meetings

4. Integrate with Workflow​

  • Add ADR creation to definition of done
  • Include ADR links in pull request templates
  • Reference ADRs in code comments where relevant
  • Use ADRs during architecture reviews

Example ADRs​

Browse example ADRs to understand different decision types:

Contributing to ADRs​

Creating New ADRs​

  1. Use the appropriate template
  2. Research alternatives thoroughly
  3. Include concrete examples and diagrams
  4. Get review from relevant stakeholders
  5. Update related documentation

Updating Existing ADRs​

  1. Create new ADR if superseding old decision
  2. Update status of old ADRs appropriately
  3. Maintain historical context and rationale
  4. Communicate changes to affected teams

Learn More: