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https://github.com/openshift-hyperfleet/architecture


https://github.com/openshift-hyperfleet/architecture

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README 

          
# HyperFleet Architecture Repository



**Status**: Active  

**Owner**: Architecture Team  

**Last Updated**: 2025-10-22  



---



## Purpose



This repository serves as the **single source of truth** for all architectural documentation related to HyperFleet. All documents are **living documents** that evolve as the design and implementation progress.



**Key Principle**: All significant architectural decisions must be documented here with their trade-offs to track technical debt and enable informed future decisions.



---



## Repository Access & MVP Process



**Current Phase**: MVP Development



**Access & Permissions**:

- All developers in the HyperFleet team are granted **write access** to this repository

- To support quick iteration during MVP, developers have **approve and merge access** if there are no objections from peers

- This temporary process enables rapid documentation of decisions and scope changes



**Repository Usage**:

- This repository primarily records:

  - Architectural decisions and their rationale

  - Trade-offs we're accepting during MVP

  - Changes to MVP scope and priorities

  - Technical debt we're consciously incurring



**Post-MVP**:

- Once MVP is complete, we will establish official processes for:

  - Repository access management

  - PR review requirements

  - Approval workflows

  - Documentation governance



**During MVP, prioritize speed over process while maintaining clear documentation of decisions.**



---



## Repository Structure



```

architecture/

├── README.md                      # This file - repository guide

├── hyperfleet/                    # HyperFleet-specific architecture

│   ├── architecture/              # 30,000 feet view (system-level)

│   │   ├── architecture-summary.md

│   │   ├── component-diagram.md

│   │   ├── data-flow-diagram.md

│   │   └── deployment-architecture.md

│   ├── components/                # Component-level design decisions

│   │   ├── api.md

│   │   ├── sentinel.md

│   │   ├── message-broker.md

│   │   ├── adapters.md

│   │   └── database.md

│   └── docs/                      # Implementation guides and features

│       ├── status-guide.md

│       ├── adapter-development-guide.md

│       ├── deployment-guide.md

│       └── monitoring-guide.md

```



---



## Document Types



### 1. Architecture Documents (`architecture/`)



**Purpose**: High-level system architecture (30,000 feet view)



**Contents**:

- System overview and goals

- Component relationships and interactions

- Data flows and communication patterns

- Deployment topology

- Cross-cutting concerns (security, scalability, observability)



**When to create**: Major system redesigns, new architecture proposals



**Living Document**: Update as system architecture evolves



---



### 2. Component Design Documents (`components/`)



**Purpose**: Detailed design for individual components



**Required Sections**:

- **What**: Component purpose and responsibilities

- **Why**: Problem it solves and context

- **How**: Technical implementation approach

- **Trade-offs**: What we gain vs what we lose (REQUIRED)

- **Dependencies**: What this component relies on

- **Interfaces**: APIs, events, data contracts

- **Configuration**: How to configure the component

- **Alternatives Considered**: What we didn't choose and why



**When to create**: New component introduction, major component redesign



**Living Document**: Update as component design evolves during implementation



---



### 3. Implementation Guides (`docs/`)



**Purpose**: Practical guides for developers and operators



**Contents**:

- Step-by-step instructions

- Code examples and patterns

- Configuration examples

- Troubleshooting tips

- Best practices



**When to create**: New feature implementation, operational procedures



**Living Document**: Keep examples current as APIs and configurations change



---



## Tracking Trade-offs and Technical Debt



**Critical Requirement**: Every component design document MUST include both:

1. **"Trade-offs" section** - What we gain and lose with the chosen approach

2. **"Alternatives Considered" section** - What other options existed and why we didn't choose them



These sections work together to provide full context for architectural decisions.



### Trade-offs Template



```markdown

## Trade-offs



### What We Gain

- ✅ Benefit 1 with measurable impact

- ✅ Benefit 2 with context

- ✅ Benefit 3



### What We Lose / What Gets Harder

- ❌ Cost 1 - Technical debt we're accepting

- ❌ Cost 2 - Capability we're giving up

- ⚠️ Risk 1 - What could go wrong



### Technical Debt Incurred

- **Debt Item 1**: Description of shortcut taken, impact, remediation plan

- **Debt Item 2**: What we should fix in the future



### Acceptable Because

- Reason 1 why the trade-off makes sense

- Reason 2 (e.g., time constraints, simplicity, MVP scope)

```



### Example: Sentinel Direct Broker Publishing



```markdown

## Trade-offs



### What We Gain

- ✅ Simpler architecture (5 components vs 6)

- ✅ Lower latency (no outbox polling)

- ✅ Easier to understand and maintain



### What We Lose / What Gets Harder

- ❌ Eventual consistency (not guaranteed delivery like outbox pattern)

- ❌ No transactional event creation with database writes

- ⚠️ Risk of events lost if broker is down and Sentinel crashes



### Technical Debt Incurred

- **No event delivery guarantees**: If Sentinel publishes to broker and crashes before updating internal state, we may duplicate events

  - **Impact**: Low (adapters are idempotent)

  - **Remediation**: Post-MVP, add event deduplication in adapters or message broker



### Acceptable Because

- MVP scope prioritizes simplicity over perfect consistency

- Cluster provisioning use case tolerates eventual consistency

- Adapters are designed to be idempotent

```



---



## Living Documents



All documents in this repository are **living documents**:



- **Update freely** as design evolves

- **Mark status** to indicate maturity (Draft, Active, Deprecated)

- **Track changes** via git commit history

- **Pay down debt** by updating "Technical Debt Incurred" sections



### Document Status



- **Draft**: Initial design, still being refined

- **Active**: Current implementation

- **Deprecated**: No longer used (link to replacement)



### Updating Documents



**When to update "Last Updated" date:**



Update the date for **meaningful changes only**:

- ✅ Component design changes

- ✅ New sections added

- ✅ Trade-offs modified

- ✅ Status changes (Draft → Active, Active → Deprecated)

- ✅ Technical debt paid down or added

- ❌ NOT for typos, formatting, or minor clarifications



**Note**: Git commit history tracks all changes. The "Last Updated" date is a quick visual indicator of the last **significant** revision.



**Steps for meaningful updates:**

1. Update the relevant sections

2. Update "Last Updated" date at the top of the document

3. If paying down technical debt, ~~strikethrough~~ the debt item and link to PR



Example of paying down technical debt:

```markdown

### Technical Debt Incurred

- ~~**No retry logic**: Adapters don't retry failed operations~~

  - **Status**: Resolved in #123

  - **Resolution**: Added exponential backoff retry logic

```



### Review and Merge Process



**MVP Process (Current)**:



All HyperFleet team developers have approve and merge access. **Goal**: Move fast while keeping the team informed.



**How to submit and merge changes:**



1. **Create a PR** with your documentation updates

2. **Add a clear description** of what changed and why

3. **Post the PR link** in Slack: #hcm-hyperfleet-team for team visibility

4. **Wait 24 hours** for peer review and objections (accounts for time zone differences between regions)

   - For urgent changes, use judgment but ensure the change is well-documented with clear rationale

   - For major architectural changes, strongly consider waiting for at least one or two Technical Leader reviews

5. **Merge when ready**: Once you have approval from peers and no objections after the 24-hour window, you may merge



**Post-MVP Process** (to be established):

- Formal approval requirements based on change type

- Required reviewers for different document categories

- Defined merge timelines and escalation paths



---



## Navigation Guide



### I want to...



**Understand HyperFleet architecture**

→ Start with `hyperfleet/architecture/architecture-summary.md`



**Design a new component**

→ Add document to `hyperfleet/components/` with required sections (see "Component Design Documents")



**Write an implementation guide**

→ Add guide to `hyperfleet/docs/` with step-by-step instructions



**Find trade-offs for a component**

→ Read component document in `hyperfleet/components/`, look for "Trade-offs" section



**Track technical debt**

→ Search all component docs for "Technical Debt Incurred"



---



## Writing Guidelines



### Trade-offs and Alternatives Are Required



Every component document MUST document both trade-offs AND alternatives considered. These go hand-in-hand:

- **Trade-offs** explain what you gain and lose with your chosen approach

- **Alternatives** explain what other options you considered and why you rejected them



Without alternatives, trade-offs lack context. Why did you accept this trade-off? What were you comparing against?



### Be Specific



❌ Bad: "This makes things faster"

✅ Good: "This reduces API latency from 200ms to 50ms"



### Quantify Impact



❌ Bad: "This improves performance"

✅ Good: "This reduces memory usage by 40%"



### Document Trade-offs Honestly



❌ Bad: "This is better in every way"

✅ Good: "This simplifies code but increases latency by 10ms"



### Include Diagrams



All architecture and component documents should include Mermaid diagrams.



---



## Diagram Guidelines



### Use Mermaid for Diagrams



All diagrams should use Mermaid syntax for:

- Maintainability (text-based, version control friendly)

- GitHub rendering (renders in markdown)

- Consistency



---



## Quality Standards



### Component Design Documents Must Have



- [ ] Clear "What" section (component purpose)

- [ ] "Why" section (problem context)

- [ ] "How" section (implementation approach)

- [ ] **"Trade-offs" section** (what we gain vs lose) - REQUIRED

- [ ] **"Alternatives Considered" section** - REQUIRED (trade-offs only exist because you chose one approach over alternatives)

- [ ] Dependencies clearly listed

- [ ] Interfaces documented (APIs, events)

- [ ] Configuration examples

- [ ] At least one diagram



**Note**: Trade-offs and Alternatives go hand-in-hand. If you document trade-offs, you MUST document what alternatives you considered and why you didn't choose them.



### Guides Must Have



- [ ] Clear target audience

- [ ] Step-by-step instructions

- [ ] Code/configuration examples

- [ ] Troubleshooting section

- [ ] Links to related documents



---



## Searching for Technical Debt



Use these commands to find technical debt across documents:



```bash

# Find all technical debt items

grep -r "Technical Debt" hyperfleet/components/



# Find all trade-offs

grep -r "## Trade-offs" hyperfleet/



# Find all "What We Lose" sections

grep -r "What We Lose" hyperfleet/



# Find deprecated documents

grep -r "Status: Deprecated" hyperfleet/

```



---



## Examples



### Good Component Document



See: `hyperfleet/components/sentinel.md`

- Clear purpose and responsibilities

- Detailed trade-offs section

- Alternatives considered

- Technical debt identified

- Diagrams included



### Good Guide



See: `hyperfleet/docs/status-guide.md`

- Step-by-step instructions

- Code examples

- Clear troubleshooting



---



## FAQ



**Q: Do I need to document every implementation detail?**

A: No. Focus on architectural decisions and component design. Implementation details belong in code comments and inline documentation.



**Q: What if I don't know the trade-offs yet?**

A: Document what you know and mark unknowns:

- "⚠️ Unknown: Performance impact needs measurement"

- "⚠️ To investigate: Scalability limits"



Update the document as you learn more.



**Q: How detailed should component docs be?**

A: Detailed enough that someone unfamiliar with the component can:

- Understand its purpose

- Understand the trade-offs

- Start implementing or operating it



Avoid implementation minutiae (that's for code comments).



**Q: Can I update someone else's document?**

A: Yes! These are living documents. Update freely as design evolves. Use git history to track changes.



**Q: When should I create a new document vs update existing?**

A: Update existing documents when:

- Refining the existing design

- Adding implementation details

- Paying down technical debt

- Fixing errors or clarifications



Create new documents when:

- Adding a completely new component

- Major redesign that deprecates old approach

- New feature guide or operational procedure



---



## Related Resources



- [C4 Model](https://c4model.com/) - Architecture diagram inspiration

- [Mermaid Documentation](https://mermaid.js.org/) - Diagram syntax

- [Technical Debt Metaphor](https://www.martinfowler.com/bliki/TechnicalDebt.html) - Understanding technical debt



---



## Contact



**Questions or suggestions?**

- Slack: //todo

- Architecture Team: //todo

- Pull requests welcome for documentation updates



---