ADR-0004: SPIKE Keeper Minimalist Design Approach

Status: accepted
Date: 2024-11-03
Tags: Security, Redundancy, Availability

Context

SPIKE Keeper serves as a critical component in our system’s key management infrastructure, working alongside SPIKE Nexus. We need to establish clear design principles for SPIKE Keeper to ensure it fulfills its role effectively and reliably.

Key considerations:

SPIKE Keeper co-exists with SPIKE Nexus on the same machine/node (this restriction can be removed if we further secure the communication between SPIKE Keeper and SPIKE Nexus with double encryption)
It serves as a recovery mechanism for SPIKE Nexus crashes
System reliability is crucial for key management
Service complexity often correlates with failure rates

Decision

We will implement SPIKE Keeper following a strict minimalist design philosophy:

Core Functionality:
- Single responsibility: maintain root key in memory
- No additional features beyond key retention
- Minimal API surface area
Implementation Constraints:
- No optional or “nice-to-have” features
- No additional endpoints unless absolutely necessary for core function
- Resist feature creep and scope expansion
- Avoid unnecessary dependencies

Consequences

Positive

Reduced points of failure
Easier to maintain and debug
Lower resource consumption
Faster startup time
Simplified testing
Higher reliability due to reduced complexity
Clear and focused code base
Easier security auditing
Reduced attack surface

Negative

May need to reject potentially useful features
Could require additional services for new functionality
Might seem limited compared to full-featured alternatives
May face pressure to add features over time

Implementation Guidelines

Code Organization

Keep codebase small and focused
Implement only essential error handling
Minimize external dependencies

Feature Evaluation Criteria

Is it essential for key retention?
Is it required for recovery scenarios?
Can it be handled by another service?

Performance Considerations

Optimize for memory usage
Keep startup time minimal
Maintain low CPU footprint

Monitoring Guidelines

Focus on essential metrics only:
- Memory usage
- Key presence
- Basic health checks
Avoid complex monitoring implementations

References

Unix philosophy of doing one thing well
Microservice design principles
KISS (Keep It Simple, Stupid) principle

Notes

Future feature requests should be evaluated against this ADR’s principles.
Any deviation from the minimalist approach requires strong justification and possibly a new ADR.