# Architecture Decision Records (ADR)
> **Project:** AuthKit
> **Status:** Active
> **Last Updated:** 2024
---
## 1. Introduction
### What are ADRs?
Architecture Decision Records (ADRs) capture important architectural decisions made during the development of AuthKit. Each ADR describes:
- **Context**: The situation that requires a decision
- **Problem**: The specific challenge or question to address
- **Decision**: The chosen approach
- **Consequences**: The outcomes, both positive and negative
- **Status**: Current state (proposed, accepted, deprecated, superseded)
### Why ADRs Matter
1. **Knowledge Preservation**: Document reasoning that might otherwise be lost
2. **Onboarding**: Help new team members understand system design
3. **Transparency**: Make decision-making visible to stakeholders
4. **Consistency**: Guide future decisions with historical context
5. **Accountability**: Track who made decisions and when
### ADR Lifecycle
```
Proposed → Accepted → [Deprecated] → Superseded
↓
Rejected
```
- **Proposed**: ADR is submitted for review
- **Accepted**: Decision is ratified by team consensus
- **Rejected**: Decision is declined
- **Deprecated**: Decision is no longer relevant
- **Superseded**: Decision has been replaced by a newer ADR
---
## 2. ADR Index
### Active Decisions
| 001 | [JWT for Token Management](adrs/001-jwt-tokens.md) | ✅ Accepted | 2024-Q1 | Security Team | #jwt #tokens |
| 002 | [OAuth 2.0 + OIDC Support](adrs/002-oauth-oidc.md) | ✅ Accepted | 2024-Q1 | Security Team | #oauth #oidc |
| 003 | [RBAC Authorization Model](adrs/003-rbac-model.md) | ✅ Accepted | 2024-Q1 | Core Team | #authorization #rbac |
| 004 | [Password Hashing Strategy](adrs/004-password-hashing.md) | ✅ Accepted | 2024-Q2 | Security Team | #security #argon2 |
| 005 | [Session Management](adrs/005-session-management.md) | ✅ Accepted | 2024-Q2 | Core Team | #sessions #stateless |
| 006 | [MFA Implementation](adrs/006-mfa-implementation.md) | ✅ Accepted | 2024-Q2 | Security Team | #mfa #totp |
| 007 | [API Key Authentication](adrs/007-api-key-auth.md) | ✅ Accepted | 2024-Q2 | Architecture | #api #keys |
| 008 | [Token Refresh Strategy](adrs/008-token-refresh.md) | ✅ Accepted | 2024-Q3 | Core Team | #tokens #security |
| 009 | [Audit Logging](adrs/009-audit-logging.md) | ✅ Accepted | 2024-Q3 | Security Team | #auditing #compliance |
| 010 | [Zero-Trust Architecture](adrs/010-zero-trust.md) | 📝 Proposed | 2024-Q4 | Security Team | #security #architecture |
### Deprecated/Superseded
| - | *No deprecated ADRs yet* | - | - |
---
## 3. Decision Drivers Summary
### Security First
- Defense in depth
- Principle of least privilege
- Secure by default
- Regular security audits
### Standards Compliance
- OAuth 2.0 RFC 6749
- OpenID Connect Core 1.0
- FAPI 2.0 security profile
- GDPR compliance
### Developer Experience
- Easy integration
- Clear documentation
- Minimal configuration
- Good error messages
### Scalability & Performance
- Stateless authentication where possible
- Efficient token validation
- Caching strategies
- Distributed session support
### Interoperability
- Multiple client types (web, mobile, service)
- Third-party identity providers
- Enterprise SSO support
- Federation capabilities
---
## 4. ADR Categories
### 🔐 Authentication (ADR-001 to ADR-010)
Decisions related to user and service authentication.
**Key Topics:**
- Password policies
- Token formats
- MFA mechanisms
- Biometric authentication
### 🛡️ Authorization (ADR-011 to ADR-020)
Authorization model and access control decisions.
**Key Topics:**
- RBAC implementation
- ABAC considerations
- Permission models
- Resource access
### 🔑 Secrets Management (ADR-021 to ADR-030)
Credential and secret handling.
**Key Topics:**
- Key storage
- Rotation policies
- Encryption at rest
- Secret injection
### 📋 Identity (ADR-031 to ADR-040)
User identity and profile management.
**Key Topics:**
- Identity providers
- User attributes
- Profile synchronization
- Identity linking
### 🏢 Enterprise (ADR-041 to ADR-050)
Enterprise-focused authentication features.
**Key Topics:**
- SAML support
- SCIM provisioning
- Directory sync
- Enterprise SSO
### 🔍 Audit & Compliance (ADR-051 to ADR-060)
Audit logging and compliance features.
**Key Topics:**
- Audit trail
- Compliance frameworks
- Data retention
- Privacy controls
---
## 5. How to Contribute New ADRs
### Before Writing an ADR
1. **Discuss First**: Open a GitHub issue or discussion to gauge interest
2. **Check Existing**: Ensure no existing ADR covers the same decision
3. **Gather Context**: Collect requirements, constraints, and options
### Writing Process
1. **Use the Template**: Copy from [templates/adr-template.md](templates/adr-template.md)
2. **Be Concise**: Focus on the decision and its context
3. **Include Options**: Document alternatives considered
4. **Be Honest**: Acknowledge trade-offs and negative consequences
### Submission Checklist
- [ ] Uses the standard ADR template
- [ ] Assigned a sequential ID
- [ ] Status set to "Proposed"
- [ ] All sections completed
- [ ] Linked in the index above
- [ ] PR submitted with clear description
### Review Process
```
1. Author submits PR with ADR in "Proposed" status
2. Maintainers review within 5 business days
3. Community feedback period (3 days minimum)
4. Decision: Accept, Request Changes, or Reject
5. If accepted, merge and update index
```
### ADR Format Requirements
**File Naming**: `XXX-descriptive-title.md`
- Three-digit sequential number (001, 002, etc.)
- Lowercase words separated by hyphens
- Place in `adrs/` directory
**Required Sections**:
1. Title and metadata
2. Context
3. Decision
4. Consequences
5. Status
6. References (optional)
---
## 6. Templates
### Standard ADR Template
```markdown
# ADR-XXX: [Title]
- **Status**: Proposed | Accepted | Rejected | Deprecated | Superseded by ADR-YYY
- **Date**: YYYY-MM-DD
- **Author**: [Name](mailto:email@example.com)
- **Tags**: #tag1 #tag2
## Context
What is the issue that we're seeing that is motivating this decision or change?
## Decision
What is the change that we're proposing or have agreed to implement?
## Consequences
What becomes easier or more difficult to do and any risks introduced by the change?
### Positive
- Benefit 1
- Benefit 2
### Negative
- Drawback 1
- Drawback 2
## Alternatives Considered
### Alternative A: [Name]
Description and why it was rejected.
### Alternative B: [Name]
Description and why it was rejected.
## References
- Link 1
- Link 2
```
### Lightweight ADR Template (for minor decisions)
```markdown
# ADR-XXX: [Title]
- **Status**: Accepted
- **Date**: YYYY-MM-DD
- **Author**: [Name]
- **Impact**: Low
## Decision
Brief description of the decision.
## Rationale
Why this decision was made.
## Consequences
- Impact 1
- Impact 2
```
### Security ADR Template (for security decisions)
```markdown
# ADR-XXX: [Title]
- **Status**: Proposed
- **Date**: YYYY-MM-DD
- **Author**: [Name]
- **Security Impact**: High | Medium | Low
- **Stakeholders**: @security-team
## Threat Model
What threat are we addressing?
## Proposed Mitigation
The security control or decision.
## Risk Assessment
| Factor | Score | Notes |
|--------|-------|-------|
| Severity | High/Med/Low | |
| Likelihood | High/Med/Low | |
| Impact | High/Med/Low | |
## Compliance
Relevant frameworks and requirements.
## Alternatives
Other security approaches considered.
```
---
## 7. Best Practices
### Do's
✅ **Focus on decisions, not just documentation**
ADRs record why we chose a particular approach, not just what the approach is.
✅ **Write them when the decision is fresh**
Capture context while it's still in recent memory.
✅ **Include the "why"**
Explain the reasoning behind the decision, not just the outcome.
✅ **Be honest about trade-offs**
Every decision has downsides. Acknowledge them.
✅ **Keep them immutable once accepted**
Don't edit accepted ADRs; supersede them with new ones instead.
✅ **Make them discoverable**
Link from README, index, and relevant code comments.
### Don'ts
❌ **Don't use ADRs for trivial decisions**
Not every code change needs an ADR. Reserve them for significant architectural choices.
❌ **Don't let them become outdated**
Update the status when decisions change.
❌ **Don't write them in isolation**
Discuss significant decisions with the team before documenting.
❌ **Don't make them overly long**
Aim for 1-2 pages. Longer ADRs may indicate scope creep.
---
## 8. Glossary
| **ADR** | Architecture Decision Record |
| **JWT** | JSON Web Token |
| **OAuth** | Open Authorization |
| **OIDC** | OpenID Connect |
| **RBAC** | Role-Based Access Control |
| **ABAC** | Attribute-Based Access Control |
| **MFA** | Multi-Factor Authentication |
| **TOTP** | Time-based One-Time Password |
| **SSO** | Single Sign-On |
| **SAML** | Security Assertion Markup Language |
| **SCIM** | System for Cross-domain Identity Management |
---
## 9. Related Resources
- [Architecture Decision Records (ADR)](https://adr.github.io/)
- [Documenting Architecture Decisions](http://thinkrelevance.com/blog/2011/11/15/documenting-architecture-decisions)
- [OAuth 2.0 Specification](https://oauth.net/2/)
- [OpenID Connect](https://openid.net/connect/)
- [AuthKit SPEC.md](./docs/SPEC.md)
- [AuthKit README.md](./README.md)
---
## 10. Maintenance
**ADR Shepherd**: Security Team
**Review Schedule**: Monthly
**Last Full Review**: 2024-Q4
---
*This index is automatically updated. Please submit a PR to add new ADRs or update existing ones.*