# SDD + GitOps Documentation Framework ## Overview The **SDD (Software Design Documentation) + GitOps Documentation Framework** is a comprehensive, structured approach to software development documentation that aligns technical work with business outcomes through clear separation of concerns. This framework ensures that every piece of documentation serves a specific purpose, reaches the right audience, and is measurable through clear KPIs and SLOs. --- ## The Documentation Matrix | Document | Purpose & Rationale (The "Why") | Audience | Format / Content | Measurement (KPI/SLO) | Example (SaaS Context) | |----------|---------------------------------|----------|------------------|----------------------|------------------------| | **Requirements** | The Business North Star. Defines exactly what problem the user has and what success looks like. It prevents "feature creep" by setting hard boundaries on what we will NOT build. | Founder, Team, PM | Format: Shared Wiki (Notion/GitHub Wiki). Content: User stories, business constraints, competitive context, and success metrics. | KPI: Business Outcomes. Measured by User Retention, Conversion Rates, and Monthly Recurring Revenue (MRR). | "The system must process high-volume math so clients see reports instantly. Goal: 15% increase in daily active users." | | **Spec** | The Technical Contract. A machine-readable, strictly typed definition of all data interfaces. It is the "Single Source of Truth" that prevents bugs caused by communication gaps between services. | Developers, QA, Automation | Format: OpenAPI/YAML or Protobuf. Content: API endpoints, snake_case key naming, data validation rules, and error response codes. | SLA/SLO: System Performance. Measured by API Uptime (99.9%), Response Latency (<100ms), and Error Rates. | A `contract.yaml` defining exactly how Julia sends Arrow data to Node.js. It forces `user_id` to be a UUID. | | **Architecture** | The Structural Blueprint. A visual map of how the components (services, DBs, networks) fit together. It shows how the data flows through the 6-node cluster and where bottlenecks live. | Senior Devs, DevOps | Format: Diagrams-as-code (Mermaid.js). Content: System Context diagrams, Database ERDs, Network Security Policies, and Infrastructure maps. | Efficiency Metrics: Resource utilization. Measured by CPU Load (<70%), RAM per pod, and internal network throughput. | A diagram showing the data path: Caddy (Proxy) → Node.js (API) → NATS (Queue) → Julia (Math Engine). | | **Walkthrough** | The Intuition & Logic. A narrative guide that explains the "steps" and "rationale" behind end-to-end flows. It's about building a mental model so devs understand why the sequence matters. | The Team, New Hires | Format: TOUR.md file or Loom Video. Content: Step-by-step traces of core features, explanation of architectural trade-offs, and "The Big Picture" flow. | Quality: Developer Velocity. Measured by "Time-to-First-Commit" for new hires and reduction in conceptual bugs. | "End-to-End Trace:" 1. UI sends JSON. 2. API wraps it in Claim-Check. 3. Julia pulls it. Rationale: To avoid NATS memory spikes. | | **Implementation** | The Functional Reality. The actual code that does the work. In SDD, the "boring" parts (types/routes) are auto-generated from the Spec to ensure the code never lies. | Developers, Reviewers | Format: Git Repository. Content: Business logic, internal helper functions, Unit Tests, and a README.md for local environment setup. | Code Health: Internal Quality. Measured by Test Coverage (90%+), Linting compliance, and Cyclomatic Complexity. | The SvelteKit frontend components and the specific Julia math-processing functions. | | **Validation** | The Enforcement Layer. Automated gates that prove the Implementation matches the Spec. It prevents human error (like changing a key name) from reaching production. | CI/CD Pipeline, QA | Format: GitHub Actions / Tests. Content: Contract tests (Dredd/Prism), Integration tests, and Security scans that run on every pull request. | Compliance: Safety Metrics. Measured by Build Success Rate and 0 "Contract Violations" in the production logs. | A CI job that blocks a Pull Request because a developer used camelCase in a database field instead of snake_case. | | **Maintenance** | The Health & Evolution. Defines how to upgrade dependencies, manage technical debt, and rotate secrets. It's the guide for "future-proofing" the software over time. | The Team, DevOps | Format: MAINTENANCE.md. Content: Dependency update schedules, Secret rotation steps, DB Migration logs, and Tech Debt "Graveyard" tracking. | Sustainability: System Longevity. Measured by "Package Age," "Security Vulnerabilities Found," and "Migration Success Rate." | "Steps to upgrade the Julia version across all 6 nodes without downtime using a Blue-Green deployment strategy." | | **Runbook** | The Operational Life-Support. The instructions for when the system is alive (or dying). In GitOps, this is the "Desired State" of the infrastructure. | DevOps, SRE, On-call Devs | Format: K8s Manifests (Flux/Argo). Content: Deployment steps, Scaling triggers, Backup/Restore procedures, and "3:00 AM" troubleshooting guides. | Reliability: Operational Health. Measured by MTTR (Mean Time to Recovery) and Error-Free Deployments. | A Flux manifest that ensures 6 replicas of the Julia service are always healthy and restarts them if they hit 80% RAM. | --- ## Detailed Breakdown of Each Document Type ### 1. Requirements **Purpose**: Establish the Business North Star The Requirements document is your anchor point. It answers the fundamental question: "What problem are we solving, and how do we know we've succeeded?" **Key Characteristics**: - **Business-Focused**: Written in business terms, not technical jargon - **Boundary-Setting**: Explicitly defines what we will NOT build - **Outcome-Oriented**: Focuses on user outcomes, not features **Best Practices**: - Include user stories that describe the user's perspective - Document business constraints (regulatory, legal, compliance) - Define competitive context and market positioning - Establish clear success metrics from day one **Common Pitfalls to Avoid**: - Vague descriptions like "improve user experience" - Changing requirements without updating the document - Not defining what's out of scope --- ### 2. Spec (Specification) **Purpose**: Create the Technical Contract The Spec serves as the Single Source of Truth for all data interfaces. It's a machine-readable definition that ensures consistency across services. **Key Characteristics**: - **Machine-Readable**: Can be parsed by tools for validation and code generation - **Strictly Typed**: Enforces data types and validation rules - **Comprehensive**: Covers all endpoints, request/response formats, and error codes **Best Practices**: - Use OpenAPI/Swagger for REST APIs or Protobuf for gRPC - Enforce consistent naming conventions (e.g., snake_case) - Define validation rules for all data fields - Document all possible error responses **Common Pitfalls to Avoid**: - Letting the spec diverge from the implementation - Incomplete error handling documentation - Not versioning the API spec --- ### 3. Architecture **Purpose**: Visualize the System Structure The Architecture document provides a visual map of how components fit together. It helps identify bottlenecks and understand data flow. **Key Characteristics**: - **Visual**: Uses diagrams to represent complex relationships - **Comprehensive**: Covers system context, data flow, and infrastructure - **Living Document**: Updated as the system evolves **Best Practices**: - Use Mermaid.js for diagrams-as-code (versionable in Git) - Include multiple views: System Context, C4 model, ERDs, network topology - Document trade-offs and architectural decisions - Show data flow through the system **Common Pitfalls to Avoid**: - Over-engineering diagrams with unnecessary detail - Not updating diagrams when the architecture changes - Using static images instead of diagrams-as-code --- ### 4. Walkthrough **Purpose**: Build Mental Models The Walkthrough document explains the "why" behind the "how." It helps developers understand the rationale behind design decisions. **Key Characteristics**: - **Narrative-Driven**: Tells a story about how the system works - **Context-Rich**: Explains trade-offs and decisions - **End-to-End**: Traces flows from user input to system output **Best Practices**: - Document step-by-step traces of core features - Explain architectural trade-offs and why you chose them - Include "The Big Picture" context - Use real examples and data flows **Common Pitfalls to Avoid**: - Only documenting the happy path - Assuming developers will figure out the "why" - Not explaining the rationale behind decisions --- ### 5. Implementation **Purpose**: The Functional Reality The Implementation is the actual code that does the work. In SDD, the "boring" parts are auto-generated from the Spec to ensure consistency. **Key Characteristics**: - **Machine-Generated**: Types and routes auto-generated from Spec - **Human-Written**: Business logic and helper functions - **Tested**: Includes unit and integration tests **Best Practices**: - Auto-generate boring parts (types, routes) from the Spec - Keep business logic separate from boilerplate - Maintain comprehensive test coverage - Document the local development setup **Common Pitfalls to Avoid**: - Hand-writing types that should be auto-generated - Inconsistent code style - Insufficient test coverage --- ### 6. Validation **Purpose**: Enforce the Contract The Validation layer provides automated gates that ensure the Implementation matches the Spec. It prevents human error from reaching production. **Key Characteristics**: - **Automated**: Runs on every commit/Pull Request - **Comprehensive**: Covers contract tests, integration tests, and security scans - **Blocking**: Prevents merges that violate the contract **Best Practices**: - Use contract testing tools (Dredd, Prism) to validate API contracts - Run integration tests on every commit - Include security scans in the CI pipeline - Fail builds on contract violations **Common Pitfalls to Avoid**: - Not running tests on every commit - Allowing manual overrides of validation gates - Not updating tests when the Spec changes --- ### 7. Maintenance **Purpose**: Ensure Long-Term Health The Maintenance document defines how to upgrade dependencies, manage technical debt, and rotate secrets. It's the guide for "future-proofing" the software. **Key Characteristics**: - **Procedural**: Step-by-step instructions for common tasks - **Scheduled**: Includes regular maintenance windows - **Documented**: Tracks technical debt and migration history **Best Practices**: - Document dependency update schedules - Create secret rotation procedures - Track technical debt in a "Graveyard" - Document migration history and rollback procedures **Common Pitfalls to Avoid**: - Ad-hoc upgrades without documentation - Ignoring technical debt until it becomes critical - Not testing upgrades in staging first --- ### 8. Runbook **Purpose**: Operational Life-Support The Runbook provides instructions for when the system is alive (or dying). In GitOps, this is the "Desired State" of the infrastructure. **Key Characteristics**: - **Action-Oriented**: Step-by-step instructions for common operations - **Automated**: Infrastructure as code defines the desired state - **Crisis-Ready**: Includes "3:00 AM" troubleshooting guides **Best Practices**: - Document deployment procedures - Define scaling triggers and procedures - Include backup and restore procedures - Create troubleshooting guides for common issues **Common Pitfalls to Avoid**: - Not documenting procedures for common issues - Not testing runbook procedures - Not versioning runbooks with the infrastructure --- ## How to Use This Approach Effectively ### Phase 1: Foundation (Week 1-2) 1. **Create Requirements Document** - Define the Business North Star - Establish success metrics - Define out-of-scope items 2. **Write the Spec** - Define all data interfaces - Establish naming conventions - Document validation rules 3. **Design Architecture** - Create system diagrams - Document data flow - Identify potential bottlenecks ### Phase 2: Development (Week 3+) 4. **Write Walkthrough** - Document end-to-end flows - Explain architectural trade-offs - Create mental models for developers 5. **Implement Code** - Auto-generate boring parts from Spec - Write business logic - Implement tests ### Phase 3: Quality Assurance 6. **Set Up Validation** - Configure CI/CD pipeline - Set up contract testing - Configure security scans 7. **Create Runbook** - Document deployment procedures - Define scaling triggers - Create troubleshooting guides ### Phase 4: Maintenance 8. **Document Maintenance** - Create dependency update schedule - Document secret rotation - Track technical debt --- ## Key Principles for Success 1. **Separation of Concerns**: Keep business concerns separate from technical concerns 2. **Machine-Readable Contracts**: Use OpenAPI/Protobuf for specs to enable automation 3. **Automation**: Automate boring parts and validation to reduce human error 4. **Measurability**: Every document should have measurable outcomes 5. **Version Control**: Keep all documentation in Git for history and collaboration 6. **Living Documents**: Update documentation as the system evolves 7. **Audience-Focused**: Write for the intended audience's needs and knowledge level --- ## Conclusion The SDD + GitOps Documentation Framework provides a comprehensive, structured approach to software development documentation. By following this framework, teams can ensure that: - Business goals are clearly defined and measurable - Technical contracts are machine-readable and enforced - System architecture is visualized and understood - Developers have clear mental models of the system - Code quality is maintained through automation - Operations are reliable and repeatable This framework is not just about documentation—it's about creating a shared understanding across the entire team and ensuring that every decision is aligned with business goals.