Atlas OS — System Architecture

Overview: The One-Box Philosophy

Atlas OS is deliberately a single-server architecture. One Hetzner CPX32 VPS (8 vCPU · 16 GB RAM · 150 GB NVMe · Nuremberg) runs the complete operational infrastructure of Atlas Corporation: CRM, finance, communications, AI, document management, fleet control, and 11 websites.

Why one box? For a solo founder, operational simplicity outweighs redundancy. One server = one bill, one SSH target, one Caddy config, one Authentik instance, and zero inter-datacenter latency. The Tailscale overlay provides device-level redundancy for access even if Caddy is down.

Network Topology

                    ┌──────────────────────────────────────────────┐
 Public Internet    │              atlas-01 (Hetzner CPX32)        │
 ─────────────      │  ┌─────────┐    ┌──────────┐                │
 Browser/App ──────►│  │  Caddy  │───►│Authentik │──► Services    │
                    │  │  (TLS)  │    │  (SSO)   │                │
                    │  └─────────┘    └──────────┘                │
                    │                                              │
 Tailscale mesh     │  ┌────────────────────────────────────────┐ │
 ────────────────   │  │  Private tailnet (100.x.x.x)           │ │
 iOS / PC / Laptop─►│  │  Webtop desktop · internal dashboards  │ │
                    │  └────────────────────────────────────────┘ │
                    └──────────────────────────────────────────────┘

Public → SSO path (every service except mail ports)

Request hits Caddy (443 → Docker port)
Caddy runs forward_auth against Authentik outpost
Authentik validates session cookie / issues redirect to login
On success: Caddy copies X-Authentik-* headers and proxies to service

Tailscale-only services

Webtop remote desktop (tailscale serve :8497)
Internal dashboards (portal, status feeds)
atlas-01 SSH (blocked on public firewall, tailnet-only)

Service Layers

Tier 0 — Identity & Security

Authentik (auth.{DOMAIN}) — OIDC/SSO, MFA, app proxies
Vaultwarden (vault.{DOMAIN}) — end-to-end encrypted password vault
Caddy — automatic TLS, reverse proxy, the sole public entry point

Tier 1 — Core Business

Odoo 19 — CRM, invoicing, project management, contacts
Nextcloud 31 — file storage, DAV (calendar/contacts sync to iOS)
Stalwart — self-hosted email: SMTP, IMAPS, JMAP, Sieve
Forgejo — self-hosted git (this very repo)

Tier 2 — Finance & Operations

Firefly III — double-entry bookkeeping, budgets, reconciliation
Enable Banking — PSD2 bank feed (ING, Knab → Firefly)
Paperless-ngx — document management, OCR, auto-tagging
n8n — workflow automation (webhooks, scheduled tasks)
Uptime Kuma — service health monitoring with alerting

Tier 3 — AI & Intelligence

LiteLLM proxy — unified OpenAI-compat API to all models (local + cloud)
Open-WebUI — ChatGPT-style UI on top of LiteLLM
Atlas Brain (atlas_brain.py) — Python signal collector, runs every 15 min
Atlas Loop — background nudge cycle, publishes to NATS
Atlas Meridian — autonomous decision engine / battle responder
Langfuse — LLM observability: every call traced with latency, cost, tokens
Local model router (:8888) — OpenAI-compat router for local Ollama models

Tier 4 — Fleet & Infrastructure

MeshCentral — remote device access, POS terminal fleet management
NATS — real-time pub/sub event bus across all Tailscale devices
Atlas heartbeat sink — aggregates device heartbeats from the NATS mesh
Atlas cockpit feeds — on-disk JSON feeds consumed by the OS desktop
Webtop — full XFCE Linux desktop in the browser (tailnet-only)

Tier 5 — Managed Sites (11 sites)

All served via Caddy. WordPress sites run in isolated Docker stacks:

Domain	Stack	Notes
`atlasworks.nl`	Docker: works-wordpress	Live WooCommerce (Caddy :8111)
`atlascorporation.nl`	Docker: corp-wordpress	Corporate site
`atlasagency.nl`	Docker: agency-wordpress	Agency services
`atlasacademy.nl`	TransIP nginx (static HTML)	Academy landing
`atlaspos.nl`	TransIP	AtlasPOS product site

Data Flow — Atlas Brain Cycle

Every 15 minutes (atlas-brain.service):
  ┌──────────────────────────────────────────┐
  │  Signal collection phase                 │
  │  ├── 7 IMAP mailboxes (read-only)        │
  │  ├── Odoo REST API (leads, contacts)     │
  │  ├── Enable Banking (bank transactions)  │
  │  └── atlas-01 health/fleet feeds         │
  └──────────────────┬───────────────────────┘
                     │
                     ▼
             atlas-state.json
                     │
                     ▼
         LLM synthesis (model router):
           atlas-auto (local) → Groq 70B → Claude Opus
                     │
                     ▼
         atlas-brief-spoken.json  (daily brief)
                     │
                     ▼
         Atlas OS cockpit panels (Today · Money · Inbox · Pipeline)

The AI Mesh

atlas-01 (NATS JetStream server)
    │
    ├── subjects:
    │     atlas.events.*      system events (disk, CPU, service state)
    │     atlas.heartbeat.*   device health pings
    │     atlas.jobs.*        delegated compute jobs (Ollama on NEBULA)
    │     atlas.brief.*       daily brief push to all devices
    │
    └── subscribers:
          Caddy PC (this machine)  ← atlas-events-collector
          NEBULA (HP EliteBook)    ← atlas-delegate-worker (5 Ollama models)
          MET-Desktop              ← Odoo failover + fleet monitor

Caddy SSO Pattern

Every SSO-gated service uses this Caddyfile block (see deploy/caddy/Caddyfile.template):

app.example.com {
  # Authentik outpost endpoints (must come first)
  reverse_proxy /outpost.goauthentik.io/* authentik-server:9000

  # SSO gate — redirects to login if no valid session
  forward_auth authentik-server:9000 {
    uri /outpost.goauthentik.io/auth/caddy
    copy_headers X-Authentik-Username X-Authentik-Groups X-Authentik-Email
                 X-Authentik-Name X-Authentik-Uid X-Authentik-Jwt
  }

  # Only reached after successful authentication
  reverse_proxy localhost:APP_PORT
}

Docker Compose Topology

Stack	File	Services
Core	`deploy/compose/atlas-core.yml`	Authentik, Nextcloud, Stalwart, Forgejo, Vaultwarden
AI	`deploy/compose/atlas-ai.yml`	LiteLLM, Open-WebUI, Langfuse
Business	`atlas-odoo.yml`	Odoo 19 + PostgreSQL
Finance	`atlas-finance.yml`	Firefly III + Paperless-ngx + Enable Banking
Fleet	`atlas-fleet.yml`	MeshCentral + NATS + Uptime Kuma
Sites	Per-site compose	WordPress stacks
Desktop	`deploy/webtop-docker-compose.yml`	Webtop (tailnet-only)

All stacks share the atlas-net Docker network. Caddy is the sole process with public port bindings (80/443). All internal services bind only to 127.0.0.1:PORT.

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