Design Principles

Summary

Den Vault favors design principles that make systems easier to understand, operate, and recover. These principles apply to both the infrastructure being documented and the way documentation itself is structured.

Why it matters

Without stable design principles, infrastructure turns into a collection of local optimizations that are difficult to audit and harder to maintain. Shared principles make it easier to evaluate tools, architecture choices, and documentation quality consistently.

Core concepts

• Systems should be understandable by inspection
• Keep it durable: back up, migrate, repair, and replace
• Leave room for care in interfaces, naming, and operational ergonomics
• Stay practical when choosing tradeoffs and tooling
• Clear trust boundaries
• Minimal exposed surface area
• Declarative configuration where possible
• Explicit ownership of data, identity, and ingress paths
• Observability and recovery designed in from the start

Practical usage

These principles usually lead to patterns such as:

• Private administrative access through VPN or dedicated management networks
• Reverse proxies and DNS as shared platform services
• Container and VM workloads with documented persistence boundaries
• Backup and restore strategy treated as a design requirement
• Low-dependency site and service architecture when that improves long-term maintainability

Best practices

• Prefer one clear pattern over multiple overlapping ones
• Keep the path of a request or dependency easy to trace
• Design around failure domains, not only nominal behavior
• Make operational boundaries visible in diagrams, inventory, and docs
• Treat usability and readability as part of technical quality

Pitfalls

• Mixing management, storage, and user traffic without a reasoned boundary
• Depending on defaults without documenting them
• Building fragile chains of dependencies for simple services
• Adding security controls that cannot be operated consistently
• Making systems colder, more complex, or more abstract than the problem requires

References

• The Twelve-Factor App
• NGINX: Reverse Proxy
• Prometheus overview