🛡️ The Sentinel – Backup Monitor

A self-hosted backup monitoring dashboard with a premium dark-theme UI, MongoDB backend, and deep integrations for Borgmatic, Uptime Kuma, Prometheus, and webhooks.

Features

Sentinel UI – Premium dark-theme dashboard built on Material 3 design tokens, Tailwind CSS, glassmorphism effects, and Manrope + Inter typography
Multi-Page SPA – Dashboard, Alert Center, Backup Hosts, Configuration
Dashboard – Bento metric cards, SVG volume trend chart, host clusters by status, live backup stream
Alert Center – Severity-based alerts (Critical/Stale) with pulse animations
Host Management – Add, edit, disable, delete hosts via Web UI
Detail Drawer – 30-day calendar heatmap, data volume chart, backup history per host
Prometheus Metrics – /metrics endpoint with per-host and global backup metrics
Uptime Kuma Integration – Automatic push forwarding per host after each backup
Webhook Notifications – Configurable alerts on error/stale events (n8n, Telegram, etc.)
API Key Auth – Optional authentication for write endpoints
90-Day History – MongoDB with automatic TTL cleanup
Auto-Refresh – Dashboard updates every 30 seconds
Zero Config – Hosts auto-register on first push

Quick Start

git clone https://github.com/feldjaeger/backup-monitor.git
cd backup-monitor
docker compose up -d
# Open http://localhost:9999

Docker Compose

services:
  backup-monitor:
    build: .
    container_name: backup-monitor
    restart: always
    ports:
      - "9999:9999"
    environment:
      - MONGO_URI=mongodb://mongo:27017
      - STALE_HOURS=26
      # - API_KEY=your-secret-key      # optional: protect write endpoints
      # - WEBHOOK_URLS=https://n8n.example.com/webhook/backup-alert
      # - WEBHOOK_EVENTS=error,stale
    depends_on:
      - mongo

  mongo:
    image: mongo:4.4    # Use 7+ if your CPU supports AVX
    container_name: backup-mongo
    restart: always
    volumes:
      - mongo_data:/data/db

volumes:
  mongo_data:

Push API

After each backup, send a POST request:

# Minimal push
curl -X POST "http://localhost:9999/api/push?host=myserver&status=ok"

# Full push with stats
curl -X POST -H "Content-Type: application/json" \
  -d '{
    "host": "myserver",
    "status": "ok",
    "duration_sec": 342,
    "original_size": 5368709120,
    "deduplicated_size": 104857600,
    "compressed_size": 83886080,
    "nfiles_new": 47,
    "nfiles_changed": 12
  }' \
  http://localhost:9999/api/push

# With API key
curl -X POST -H "X-API-Key: your-key" \
  "http://localhost:9999/api/push?host=myserver&status=ok"

Borgmatic Integration

Add to your borgmatic.yml:

after_backup:
  - >-
    bash -c '
    STATS=$(borgmatic info --archive latest --json 2>/dev/null | python3 -c "
    import sys,json
    d=json.load(sys.stdin)[0][\"archives\"][-1]
    s=d.get(\"stats\",{})
    print(json.dumps({
      \"host\":\"$(hostname)\",
      \"status\":\"ok\",
      \"duration_sec\":int(s.get(\"duration\",0)),
      \"original_size\":s.get(\"original_size\",0),
      \"deduplicated_size\":s.get(\"deduplicated_size\",0),
      \"compressed_size\":s.get(\"compressed_size\",0),
      \"nfiles_new\":s.get(\"nfiles\",0)
    }))" 2>/dev/null || echo "{\"host\":\"$(hostname)\",\"status\":\"ok\"}");
    curl -fsS -m 10 -X POST -H "Content-Type: application/json" -d "$STATS" "http://YOUR_SERVER:9999/api/push" || true
    '

on_error:
  - >-
    curl -fsS -m 10 -X POST -H "Content-Type: application/json"
    -d '{"host":"'$(hostname)'","status":"error","message":"Backup failed"}'
    "http://YOUR_SERVER:9999/api/push" || true

API Reference

Method	Endpoint	Auth	Description
`GET`	`/`	❌	Web UI
`GET`	`/metrics`	❌	Prometheus metrics
`GET`	`/api/summary`	❌	Dashboard summary
`GET`	`/api/hosts`	❌	List all hosts with status
`GET`	`/api/history/<host>?days=30`	❌	Backup history
`GET`	`/api/calendar/<host>?days=30`	❌	Calendar heatmap data
`POST`	`/api/push`	🔑	Push backup status
`POST`	`/api/hosts`	🔑	Add a host
`PUT`	`/api/hosts/<name>`	🔑	Update host settings
`DELETE`	`/api/hosts/<name>`	🔑	Delete host and history

🔑 = requires API_KEY if set (via X-API-Key header or ?api_key= query param)

Prometheus Integration

backup_hosts_total 21
backup_host_status{host="myserver"} 1          # 1=ok, 0=error, -1=stale
backup_host_last_seconds{host="myserver"} 3600
backup_host_duration_seconds{host="myserver"} 342
backup_host_size_bytes{host="myserver"} 5368709120
backup_host_dedup_bytes{host="myserver"} 104857600
backup_today_total 22
backup_today_bytes 47280909120

Add to prometheus.yml:

scrape_configs:
  - job_name: 'backup-monitor'
    static_configs:
      - targets: ['backup-monitor:9999']
    scrape_interval: 60s

Webhook Notifications

environment:
  - WEBHOOK_URLS=https://n8n.example.com/webhook/backup-alert
  - WEBHOOK_EVENTS=error,stale

Payload:

{
  "event": "error",
  "host": "myserver",
  "message": "Backup failed",
  "timestamp": "2026-04-05T06:00:00Z"
}

Uptime Kuma Integration

Create a Push monitor in Uptime Kuma
In Backup Monitor: Host → Edit → paste Kuma Push URL
After each backup, status is automatically forwarded to Kuma

Environment Variables

Variable	Default	Description
`MONGO_URI`	`mongodb://mongo:27017`	MongoDB connection
`STALE_HOURS`	`26`	Hours without backup → stale
`API_KEY`	(empty)	Set to enable auth on write endpoints
`WEBHOOK_URLS`	(empty)	Comma-separated notification URLs
`WEBHOOK_EVENTS`	`error,stale`	Events that trigger webhooks

Design System

The UI follows The Sentinel design language:

Colors: Material 3 tonal palette with deep slate surfaces (#0b1326 → #2d3449)
Typography: Manrope (headlines) + Inter (body/data)
No-Line Rule: Card boundaries via background color shifts, no 1px borders
Glass Effect: Backdrop-blur on navigation and overlays
Pulse Animations: Status indicators with two-tone glow effects
Tonal Depth: Layered surfaces creating architectural permanence

Tech Stack

Backend: Python 3.12, Flask, Gunicorn
Database: MongoDB 4.4+
Frontend: Tailwind CSS, Vanilla JS, Material Symbols, Google Fonts
No build step – Tailwind loaded via CDN

License

MIT

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