thesabear
5a96e92dc6
Switch to LR layout, restore all 12 observability-reporting edges (cut them by mistake, they belong in a dependency graph), drop the repeated 'reports to' label text that was breaking legibility and let line style (solid=dependency, dotted=async reporting) carry that distinction instead. Also shortened edge labels on the trust-boundary diagram to avoid the same clipping issue.
4.3 KiB
📐 Architecture Overview
Note
The stable, directional laws governing how traffic moves through the fleet — eight distinct traffic categories (ingress, east-west, secrets, DNS, observability, notifications, CI/CD, management), each with its own routing authority and its own failure behavior.
Dependency graph
flowchart LR
Internet(["Internet"]) --> Edge["Edge Firewall"]
Edge --> LAN["LAN"]
LAN --> DNS["Internal DNS"]
LAN --> Vault["Vault"]
DNS --> Vault
Vault --> Apps["App Host<br/>~40 stacks"]
Vault --> Automation["Automation Host"]
LAN --> FileServer["File Server"]
DNS --> FileServer
LAN --> Automation
Apps --> InternalProxy["Internal Proxy Zone"]
Apps --> SSO["SSO"]
Automation --> GitHost["Git Hosting"]
Vault --> EdgeProxy["User-Facing Proxy<br/>mTLS"]
DNS --> EdgeProxy
Apps -.proxied.-> EdgeProxy
SSO -.auth.-> EdgeProxy
Apps -.-> Monitoring["Monitoring"]
Automation -.-> Monitoring
FileServer -.-> Monitoring
Vault -.-> Monitoring
DNS -.-> Monitoring
EdgeProxy -.-> Monitoring
Apps -.-> SecMon["Security Monitoring"]
Automation -.-> SecMon
FileServer -.-> SecMon
Vault -.-> SecMon
DNS -.-> SecMon
EdgeProxy -.-> SecMon
Tip
Solid arrows are real dependencies — the target has to be reachable and healthy for the source to function. Dotted arrows into Monitoring and Security Monitoring are the one exception: every host reports telemetry to both, but per the Observability Independence Law below, that reporting is asynchronous and non-blocking — nothing here actually depends on Monitoring or Security Monitoring being up. The line style carries that distinction instead of repeating "reports to" twelve times. Full detail on what's actually collected:
docs/observability.mdanddocs/security-monitoring.md.
Four trust boundaries, not two
flowchart LR
WAN["WAN"] -->|public| EdgeFW["Edge Firewall<br/>public proxy"]
Browser["LAN browsers"] -->|mTLS + SSO| UserProxy["User-facing proxy"]
Service["App-to-app"] -->|allowlist + SSO| InternalProxy["Internal proxy"]
Infra["LAN infra-to-infra"] -->|per-flow rule| HostFW["Host firewall"]
Backend services trust proxy headers, not raw client IP, on every path.
Two structurally independent traffic planes
| Plane | Path |
|---|---|
| Ingress — public | Client → edge firewall/proxy → backend |
| Ingress — LAN-facing | Client → user-facing proxy (mTLS) → backend |
| East-west — app-to-app | Service → internal proxy zone → service |
| East-west — infra-to-infra | Service → firewall rule → service, direct, no proxy |
Important
Observability sits outside every request path on purpose. Logs and metrics push asynchronously to monitoring infrastructure; nothing in that pipeline is inline with application traffic, and application services don't depend on monitoring availability. If monitoring goes down, collection stops — nothing else does.
Two real architecture changes, not a static design
Important
This shape isn't how the fleet started — it's evolved twice, deliberately. The public-facing reverse proxy used to run as its own dedicated VM; it was consolidated directly onto the edge firewall as a package instead, removing an entire host from the public-ingress path without losing any functionality — one less thing that can fail, one less thing to patch and monitor independently. And the internal service-to-service model used to be a flat, unauthenticated mesh network; it was fully replaced by the two-zone split in
docs/dns-naming.md, trading a simpler-but-weaker model for one with a real trust boundary between browser-facing and app-to-app traffic. Both changes reduced the attack surface at the cost of more moving parts to reason about — a tradeoff made deliberately, not stumbled into.
What this map deliberately excludes
Not a firewall rule listing, not a port inventory, not a service configuration reference — those live in their own docs (docs/firewall-and-network.md and elsewhere). This is strictly the stable, directional shape of how trust and traffic actually move.