Decision Process
Overview
The Architecture Practice uses a structured decision-making process to ensure that architectural decisions are well-documented, thoroughly evaluated, and aligned with organizational strategy. This process is based on the Architecture Decision Record (ADR) format, which captures the context, decision, and consequences of significant architectural choices.
Decision Lifecycle:
Identification → Evaluation → Decision → Documentation → Implementation → Review
Types of Architectural Decisions
Category 1: Strategic Decisions (Tier 1)
Definition: Decisions affecting organizational architecture strategy, technology direction, or multiple business units
Examples:
- Cloud provider selection (primary vs multi-cloud)
- Microservices vs monolithic architecture adoption
- API platform and gateway selection
- Data warehouse/lake technology selection
- Messaging platform (Kafka vs RabbitMQ vs other)
- Kubernetes adoption as standard container platform
- Multi-tenancy model for SaaS applications
- AI/ML platform and tooling selection
Decision Authority: CTO, VP Architecture Review Board: Architecture Review Board (ARB) Approval Timeline: 4-6 weeks Documentation Level: Detailed ADR (8-15 pages) Scope: Affects 3+ business units or 5+ systems Communication: All-hands announcement, training required
ADR Template: Mandatory, detailed, with alternatives evaluation matrix
Category 2: System Architecture Decisions (Tier 2)
Definition: Decisions affecting specific system or application architectures, involving significant trade-offs
Examples:
- Service decomposition boundaries and sizing
- Database architecture (polyglot vs single database)
- Caching strategy (in-memory, distributed, client-side)
- Event-driven vs request-response patterns
- Deployment strategy (containers, serverless, VMs)
- Authentication and authorization approach
- API design paradigm (REST, GraphQL, gRPC)
- State management approach
- Testing strategy (unit, integration, E2E coverage)
Decision Authority: Senior Architect, Domain Champion Review Board: Domain expert review + architecture peer review Approval Timeline: 2-4 weeks Documentation Level: Standard ADR (5-10 pages) Scope: Affects 1-2 business units or 2-3 systems Communication: Team communication, documentation update
ADR Template: Standard format with impact analysis
Category 3: Tactical Decisions (Tier 3)
Definition: Implementation-level decisions with localized impact, standard patterns applied
Examples:
- Technology library/framework selection
- Code organization and directory structure
- Logging framework and log aggregation
- Monitoring and alerting approach
- CI/CD pipeline configuration
- Testing framework selection
- Documentation tool selection
- Dependency management approach
- Code quality tool selection
Decision Authority: Technical Lead, Senior Developer Review Board: Peer review, optional architecture review Approval Timeline: 1-2 weeks Documentation Level: Brief ADR (2-4 pages) or technical note Scope: Affects single team or system component Communication: Team notification, documentation
ADR Template: Lightweight format or technical decision note
Category 4: Operational Decisions (Tier 0)
Definition: Routine decisions following established procedures, no documentation required
Examples:
- Release schedule decisions (within approved windows)
- Incident response procedures (follow playbooks)
- Maintenance scheduling (within governance)
- Tool configuration (standard settings)
- Access provisioning (follow RBAC policies)
- Environment setup (follow templates)
Decision Authority: Team lead or manager Approval Timeline: Immediate Documentation Level: None (unless exceptional) Communication: Status updates only
Decision Identification Process
Who Can Initiate Decisions?
- Architects at any level
- Technology leads and senior developers
- Product managers and stakeholders
- Operations and infrastructure teams
- CTO/VP Architecture (strategic initiatives)
Decision Triggers
Decisions are initiated when facing:
- Technology Selection Uncertainty
- Need to choose between 3+ viable options
- Significant investment or switching cost
- Affects multiple teams or systems
- Architectural Trade-off Evaluation
- Significant performance/scalability/security trade-off
- Multiple valid approaches with different implications
- Long-term architectural implications
- Risk Mitigation
- Identifying and mitigating significant risks
- Security or compliance implications
- Operational or reliability concerns
- Standard Process Decisions
- Establishing team norms and standards
- Process improvements or changes
- Organizational policies
Decision Criteria Checklist
Before initiating a formal decision process, verify:
- Multiple viable options exist (2+)
- Significant impact or investment involved
- Affects current or future systems
- Reversibility of decision is low
- Organizational learning value is high
- Stakeholder buy-in is needed
- Long-term implications need evaluation
Evaluation Phase
Option Generation
For Tier 1 & 2 decisions, identify and document:
- Primary Option (recommended approach)
- Advantages and disadvantages
- Implementation approach
- Cost and effort estimate
- Risk assessment
- Timeline implications
- Alternative Options (2-3 alternatives)
- Each alternative documented similarly
- Comparison against selection criteria
- Why it was not chosen
- Status Quo Option
- Cost of doing nothing
- Risks of not deciding
- Technical debt implications
Evaluation Criteria
Establish and weight criteria before evaluation:
Common Criteria Categories:
| Category | Example Criteria |
|---|---|
| Technical | Performance, scalability, maintainability, complexity, integration capability, learning curve |
| Business | Cost (initial + operational), time-to-market, competitive advantage, ROI, vendor lock-in |
| Operational | Supportability, monitoring/debugging, disaster recovery, automation capability, team skills |
| Risk | Security, compliance, vendor stability, community adoption, deprecation risk |
| Strategic | Alignment with roadmap, technology direction, organizational capabilities |
Evaluation Methods
For Tier 1 Decisions:
- Weighted scoring matrix (each option scored against criteria)
- Proof of concept evaluation (if high uncertainty)
- Market research and vendor briefings
- Peer organization case studies
- Expert advisory consultation
For Tier 2 Decisions:
- Quick scoring matrix (simplified)
- POC if complexity is high
- Internal pilot or spike evaluation
- Expert review
For Tier 3 Decisions:
- Quick comparison (verbal, informal documentation)
- Precedent review (how similar decisions made)
- Team discussion
Stakeholder Consultation
Tier 1 Decisions:
- CTO/VP Architecture approval required
- ARB review required
- Affected business unit leaders consulted
- Technology leads from affected systems
- Security/compliance reviewed if applicable
Tier 2 Decisions:
- Domain champion consultation
- Affected technical leads
- Security review if applicable
- Optional ARB review if cross-cutting
Tier 3 Decisions:
- Affected technical team
- Optional peer review
- No formal approval required
Decision Making
Decision Making Styles (Chosen by Authority)
- Consultative (Common for Tier 1 & 2)
- Authority consults with stakeholders
- Feedback is considered but not binding
- Authority makes final decision
- Consensus Seeking (Common for team-level decisions)
- Group discussion until consensus emerges
- Authority may override if needed
- Full team buy-in expected
- Delegated (For routine decisions)
- Authority delegates to expert/delegate
- Quick review before implementation
- Feedback loop for learning
Decision Review Meeting
For Tier 1 Decisions (ARB Review):
Attendees:
- Decision requester/sponsor
- Evaluation team lead
- ARB members (minimum 3)
- Affected technical leads
- Security/compliance representative (if applicable)
Meeting Agenda (1-2 hours):
- Problem statement and context (10 min)
- Evaluation methodology and criteria (10 min)
- Option 1 presentation (15 min)
- Option 2 presentation (15 min)
- Alternative(s) presentation (10 min)
- Discussion and questions (20 min)
- Recommendation and vote (10 min)
- Next steps (5 min)
Decision Outcomes:
- ✅ Approved: Proceed with recommended option
- ✅ Approved with Conditions: Approved subject to mitigations
- ⚠️ Deferred: Gather more information, revisit
- ❌ Rejected: Option not approved, explore alternatives
Approval Gates
Tier 1 (Strategic):
- ARB vote: 2/3 majority required
- CTO/VP Architecture sign-off required
- Compliance/security approval (if applicable)
- Timeline: 4-6 weeks from submission
Tier 2 (System Architecture):
- Domain champion approval required
- Architecture peer review (at least 1)
- Optional ARB review if cross-cutting
- Timeline: 2-4 weeks from submission
Tier 3 (Tactical):
- Technical lead approval
- Optional peer review
- Timeline: 1-2 weeks from submission
Documentation
ADR Format and Structure
All Tier 1 and Tier 2 decisions documented as Architecture Decision Records:
# ADR-NNN: Title
## Status
[Proposed | Accepted | Deprecated | Superseded by ADR-XXX]
## Context
[Description of the issue forcing this decision, including:
- Problem statement
- Business drivers
- Technical constraints
- Organizational context
- Stakeholders affected]
## Decision
[Clear statement of the architectural decision made]
## Rationale
[Explanation of why this decision was made, including:
- Evaluation of alternatives
- Key trade-offs
- Risk mitigation
- Alignment with strategy]
## Consequences
[Positive and negative consequences of this decision:
- Immediate consequences
- Long-term implications
- Risks and mitigations
- Implementation impact]
## Alternatives Considered
[Summary of alternatives evaluated:
- Alt 1: [Option description]
Pros: ... Cons: ...
- Alt 2: [Option description]
Pros: ... Cons: ...]
## Implementation Notes
[Practical guidance for implementation:
- Timeline
- Dependencies
- Team skills required
- Rollout strategy
- Success criteria]
## Related Decisions
[Links to related ADRs:
- ADR-XXX: [Related decision]
- ADR-YYY: [Related decision]]
## References
[Links to relevant documents, standards, case studies]
ADR Naming and Location
Location: /docs/decisions/adr-NNN.md
Numbering:
- Sequential: ADR-001, ADR-002, ADR-003, etc.
- Format: Zero-padded to 3 digits
- Title format: ADR-NNN: Decision title
Example ADR
# ADR-042: Use Kubernetes for Container Orchestration
## Status
Accepted (October 2025)
## Context
Our organization is scaling from 10 to 50+ services, with increasing operational complexity. Current VM-based deployment is difficult to manage, limiting deployment velocity. We need a container orchestration platform that:
- Supports 50+ services across 3 environments
- Enables rapid deployments (target: 10 deployments/day)
- Supports multiple teams and business units
- Provides observability and debugging capabilities
- Can scale horizontally
Key stakeholders: Platform engineering, development teams (15 teams), security/compliance
## Decision
We will standardize on Kubernetes as our container orchestration platform, using managed Kubernetes (AWS EKS or Azure AKS) to reduce operational burden.
## Rationale
Evaluated three options:
1. **Kubernetes (Selected)**
- Pros: Industry standard, large ecosystem, excellent tooling, vendor-neutral, supports all workload types, strong observability
- Cons: Learning curve, operational complexity, networking model requires expertise
- Cost: $150K/year managed service
2. **Docker Swarm**
- Pros: Simpler than Kubernetes, integrated with Docker ecosystem
- Cons: Limited ecosystem, declining adoption, poor auto-scaling, limited observability
- Cost: $80K/year
3. **Serverless (AWS Fargate)**
- Pros: Minimal operational burden, auto-scaling, pay-per-execution
- Cons: Expensive for constant workloads, limited debugging, vendor lock-in, not suitable for batch/scheduled jobs
- Cost: $320K/year estimated
Kubernetes selected because:
- Aligns with market direction and industry adoption
- Supports diverse workload types and teams
- Strong ecosystem with mature tooling
- Enables rapid deployment and auto-scaling
- Ecosystem reduces lock-in risk
## Consequences
**Positive:**
- Standardized container orchestration across organization
- Enables 50+ services at scale with single platform
- Team self-service deployment capability
- Strong observability and debugging tools available
- Reduces operational toil vs. VM-based deployments
**Negative:**
- 3-month ramp-up period for teams (training and practice)
- Initial infrastructure investment in monitoring, logging, ingress
- Requires infrastructure team expansion (2-3 people)
- Networking and security model requires careful design
**Risks and Mitigations:**
- Risk: Teams don't understand Kubernetes → Mitigation: Mandatory training (40 hours)
- Risk: Cost overruns → Mitigation: Resource quotas per team, monthly monitoring
- Risk: Outages → Mitigation: Multi-region setup, PagerDuty integration, runbooks
## Implementation Notes
**Timeline:**
- Phase 1 (Months 1-2): Infrastructure setup, monitoring/logging, security
- Phase 2 (Months 2-3): Pilot team migration (2 services)
- Phase 3 (Months 3-6): Full rollout (50 services, 15 teams)
- Phase 4 (Months 6-9): Optimization and cost tuning
**Team Structure:**
- Platform engineering team: 3-4 people (cluster management, platform services)
- Architecture support: 2 architects (migration guidance, design reviews)
- Training: 1 trainer (courses and workshops)
**Success Criteria:**
- 100% of containerized services running on Kubernetes by month 9
- Deployment frequency: 10+ deployments/day (up from 2/day)
- P99 deployment time: < 30 minutes (down from 4 hours)
- Cluster uptime: 99.9% (SLA requirement)
- Team satisfaction: 4.0+ / 5.0 (survey)
Implementation Phase
Pre-Implementation Checklist
Before implementing a decision:
- ADR approved and published
- All stakeholders notified and bought-in
- Resource plan finalized
- Timeline and milestones established
- Success criteria defined
- Risk mitigation strategies in place
- Training or ramp-up plan created
- Communication plan documented
Implementation Tracking
Decision Tracking Dashboard:
- Status of all active decisions (proposed, in-progress, implemented)
- Implementation progress against timeline
- Risk status and any issues encountered
- Stakeholder feedback
Monthly Review:
- Review of decisions implemented in past month
- Status of in-progress decisions
- Issues and mitigations
- Lessons learned
Review and Feedback
Post-Implementation Review
After implementation (timing depends on decision):
- Technical Review (1-3 months)
- Are the expected technical benefits realized?
- Any unexpected technical issues?
- Performance, scalability, operational impact assessment
- Recommendations for improvement
- Business Review (3-6 months)
- Are business objectives being met?
- ROI and cost analysis
- Team adoption and satisfaction
- Any unforeseen business impacts?
- Lessons Learned (Post-implementation)
- What worked well?
- What would we do differently?
- Recommendations for similar decisions
- Training or documentation updates needed
Decision Retirement
Decisions may be superseded or deprecated when:
- Superseded: Better decision made that replaces this one
- Example: ADR-042 (Kubernetes) supersedes previous container strategy
- Update ADR status to “Superseded by ADR-XXX”
- Archive old ADR but keep for historical reference
- Deprecated: Technology or approach no longer recommended
- Example: ADR-035 (Flash technology) deprecated as Flash EOL
- Update ADR status to “Deprecated (as of date)”
- Document reason for deprecation
- Provide migration guidance
Decision Governance
Architecture Review Board (ARB)
The ARB meets weekly to review Tier 1 decisions and discuss architecture strategy:
Members:
- VP Architecture (chair)
- 4 Principal Architects (one per domain)
- CTO (optional, for strategic reviews)
Meeting Cadence: Weekly, 1 hour Minutes: Documented with decisions and action items
Decision Authority Matrix
| Decision Tier | Authority | Review | Timeline |
|---|---|---|---|
| Tier 1 (Strategic) | CTO/VP Architecture | ARB vote | 4-6 weeks |
| Tier 2 (System) | Senior Architect/Domain Champion | Peer review | 2-4 weeks |
| Tier 3 (Tactical) | Technical Lead | Optional peer | 1-2 weeks |
| Tier 0 (Operational) | Team Lead | None | Immediate |
Escalation Procedure
Tier 3 Technical Disagreement
↓ (Cannot reach consensus)
Escalate to Domain Champion (Tier 2)
↓ (Still unresolved)
Escalate to VP Architecture (Tier 1)
↓ (Strategic implications)
Escalate to CTO (Final decision)
Related Resources
- Architecture Decision Record Template
- Technology Evaluation Guide
- Architecture Review Board
- Architecture Standards
- Communication Plan
Status: Complete
Last Updated: November 2025
Version: 1.0
Owner: VP Architecture