Documentation Index
Fetch the complete documentation index at: https://docs.verifow.com/llms.txt
Use this file to discover all available pages before exploring further.
This guide covers scaling strategies for both deployment models: SaaS (multi-tenant) and Dedicated VPS (single-tenant). Choose the model that fits your customer’s security requirements and budget.
Deployment Models Overview
| Factor | SaaS Multi-Tenant | Dedicated VPS (Single-Tenant) |
|---|
| Tenants per server | 10–100+ banks | 1 bank |
| Infrastructure cost | Shared across tenants | Paid by individual customer |
| Data isolation | Logical (row-level) | Physical (separate server) |
| Onboarding time | 5 minutes | 2–3 hours |
| Monthly price to customer | ₦50K–₦500K | ₦500K–₦2M+ |
| Best for | Most banks & fintechs | Tier-1 banks, government agencies |
| Compliance level | CBN compliant + ISO 27001 | CBN compliant + air-gapped option |
SaaS Scaling Architecture
Phase 1: Single Server (0–10 Customers)
┌─────────────────────────────────────────┐
│ Single VPS ($40–$80/mo) │
│ ┌─────────┐ ┌─────────┐ ┌─────────┐ │
│ │ Nginx │ │Ratel App│ │ Postgres│ │
│ │ (SSL) │ │(API+UI) │ │ 16 │ │
│ └────┬────┘ └────┬────┘ └─────────┘ │
│ │ │ │
│ ┌────┴────────────┴────┐ ┌─────────┐ │
│ │ Redis 7 │ │ Watchman│ │
│ │ (cache/queues) │ │(sanctions)│
│ └──────────────────────┘ └─────────┘ │
└─────────────────────────────────────────┘
Handles: ~100 transactions/second, ~50 concurrent dashboard users
Docker Compose services on one host:
ratel-app (API + dashboard)ratel-postgresratel-redisratel-minioratel-watchmanratel-marble (optional)ratel-tirreno (optional)
Phase 2: Split App & Database (10–50 Customers)
When CPU or RAM consistently exceeds 70%:
┌─────────────────────┐ ┌─────────────────────┐
│ App VPS ($40/mo) │◄───────►│ DB VPS ($40/mo) │
│ ┌───────────────┐ │ private│ ┌───────────────┐ │
│ │ Nginx + SSL │ │ network│ │ Postgres 16 │ │
│ │ Ratel App │ │ (VPC) │ │ (primary) │ │
│ │ Redis │ │ │ └───────────────┘ │
│ │ Watchman │ │ │ │
│ └───────────────┘ │ └─────────────────────┘
└─────────────────────┘
- Move Postgres to its own VPS
- Connect via private network (DigitalOcean VPC)
- Update
DATABASE_URL in .env to point to the DB VPS private IP
# On app VPS, update .env
DATABASE_URL="postgresql://ratel:PASSWORD@10.124.0.3:5432/ratel_security"
Phase 3: Load Balanced App Tier (50–200 Customers)
┌─────────────────┐
│ Cloudflare / │
│ DigitalOcean │
│ Load Balancer │
└────────┬────────┘
│
┌────────────────┼────────────────┐
▼ ▼ ▼
┌────────────┐ ┌────────────┐ ┌────────────┐
│ App VPS 1 │ │ App VPS 2 │ │ App VPS 3 │
│ (ratel-app)│ │ (ratel-app)│ │ (ratel-app)│
│ (watchman) │ │ (watchman) │ │ (watchman) │
└────────────┘ └────────────┘ └────────────┘
│ │ │
└────────────────┼────────────────┘
▼
┌─────────────────────┐
│ DB Cluster │
│ Postgres Primary │
│ + Read Replica │
└─────────────────────┘
- Run 2–3 app servers behind a load balancer
- Use sticky sessions (dashboard uses JWT, so stateless -any server works)
- Add Postgres read replica for analytics/reporting queries
- Redis stays on each app server (caches are independent) or move to Redis Cloud / Upstash
Phase 4: Managed Services (200+ Customers)
Replace self-hosted components with managed services:
| Component | Self-Hosted | Managed Alternative | Why Switch |
|---|
| Postgres | ratel-postgres | DigitalOcean Managed Postgres | Automated backups, failover, scaling |
| Redis | ratel-redis | Upstash Redis | Serverless, global replication |
| Object Storage | ratel-minio | AWS S3 / DigitalOcean Spaces | Infinite scale, CDN integration |
| Queue | BullMQ on Redis | AWS SQS / RabbitMQ | Better observability, DLQ handling |
┌─────────────┐ ┌─────────────┐ ┌─────────────────────────────┐
│ CDN │────►│ API Gateway │────►│ Kubernetes / DO App Platform│
│(static UI) │ │ (rate limit) │ │ (auto-scaling app pods) │
└─────────────┘ └─────────────┘ └─────────────────────────────┘
│
┌────────────────────────────────────────┼────────────────────────┐
▼ ▼ ▼
┌─────────────────────┐ ┌─────────────────────┐ ┌──────────────────┐
│ Managed Postgres │ │ Upstash Redis │ │ DO Spaces / S3 │
│ (primary + replica)│ │ (caching + queues) │ │ (documents, XML)│
└─────────────────────┘ └─────────────────────┘ └──────────────────┘
Dedicated VPS Scaling
For enterprise customers who demand their own server, use the automated provisioning script:
./scripts/provision-bank-vps.sh \
--bank-name "First Bank of Nigeria" \
--slug "firstbank" \
--domain "compliance.firstbank.ng" \
--admin-email "admin@firstbank.ng" \
--with-engines
What the Script Creates
┌─────────────────────────────────────────────┐
│ Dedicated VPS (per customer) │
│ │
│ ┌─────────┐ ┌─────────┐ ┌─────────────┐ │
│ │ Nginx │ │Ratel App│ │ Postgres │ │
│ │+ Certbot│ │+Dashboard│ │ 16 │ │
│ │ (SSL) │ │+API │ │ │ │
│ └────┬────┘ └────┬────┘ └─────────────┘ │
│ │ │ │
│ ┌────┴────────────┴────┐ ┌─────────────┐ │
│ │ Redis 7 │ │ Watchman │ │
│ │ (cache/queues) │ │ (sanctions) │ │
│ └──────────────────────┘ └─────────────┘ │
│ │
│ Systemd: ratel-firstbank.service │
│ Logs: /var/log/ratel-firstbank/ │
│ Firewall: UFW (22, 80, 443 only) │
└─────────────────────────────────────────────┘
Scaling a Single Dedicated VPS
If one bank outgrows their VPS:
Option A: Vertical Scaling (easiest)
# Resize the droplet via DigitalOcean UI or CLI
doctl compute droplet-action resize <droplet-id> --size s-4vcpu-8gb
- Move Postgres to a separate managed database
- Keep app + Redis + Watchman on the original VPS
- Update
DATABASE_URL to point to the managed DB
Option C: High Availability
- 2 app servers + 1 managed DB + DigitalOcean Load Balancer
- This is essentially the SaaS architecture, but isolated to one customer
Scaling Decision Tree
Are you just starting out?
│
├── YES ──► Start with SaaS on ONE VPS (Phase 1)
│ └── Cost: ~$40/month
│
└── NO ──► How many paying customers?
│
├── 1–10 ──► SaaS Phase 1 (single server)
│
├── 10–50 ──► SaaS Phase 2 (split app + DB)
│
├── 50–200 ──► SaaS Phase 3 (load balanced)
│
├── 200+ ──► SaaS Phase 4 (managed services)
│
└── Enterprise customer demands dedicated server?
└── Dedicated VPS (provision-bank-vps.sh)
└── Upsell: +₦500K/month over SaaS plan
These are conservative estimates on DigitalOcean droplets:
| Droplet | vCPU | RAM | Transactions/sec | Concurrent Users | Tenants (SaaS) |
|---|
| Basic | 2 | 4 GB | ~30 | 20 | 5–10 |
| General | 4 | 8 GB | ~100 | 50 | 10–50 |
| General | 8 | 16 GB | ~250 | 150 | 50–150 |
| CPU-Optimized | 8 | 16 GB | ~500 | 300 | 150–300 |
Note: Actual throughput depends on rule complexity, sanctions list size, and whether Marble/Tirreno engines are enabled.
Monitoring & Alerting
Set up monitoring before you have 10+ customers:
DigitalOcean Monitoring (built-in)
Enable in the DO console for CPU, memory, disk, and bandwidth alerts.
Uptime Monitoring
# Simple cron health check
crontab -e
# Add this line (checks API every 5 minutes, alerts via webhook if down)
*/5 * * * * curl -f http://localhost:3001/api/v1/health || curl -X POST YOUR_ALERT_WEBHOOK
Log Aggregation
For 50+ customers, ship logs to a central service:
# Install Vector or Fluentd on each app server
# Ship to Datadog, Grafana Cloud, or self-hosted Loki
Security at Scale
SaaS Security
| Layer | Implementation |
|---|
| Network | UFW firewall, VPC private networking |
| Database | Row-level tenant isolation, encrypted at rest |
| API | Rate limiting per tenant, JWT auth, API key rotation |
| Dashboard | Role-based access control (RBAC), session expiry |
| Files | MinIO/S3 with signed URLs, no public buckets |
| Audit | Immutable audit chain with SHA-256 hashing |
Dedicated VPS Security
Same as SaaS, plus:
- Physical isolation -no shared server with other tenants
- Custom domain + SSL -bank-branded compliance portal
- IP whitelisting -restrict dashboard access to bank office IPs
- Air-gapped option -no internet egress except for sanctions list updates
Cost Comparison (Monthly, USD)
SaaS Single Server (Phase 1)
| Component | Cost |
|---|
| DigitalOcean droplet (4vCPU/8GB) | $48 |
| Backups (20% of droplet) | $10 |
| Domain + SSL (Let’s Encrypt) | $0 |
| Total | ~$58 |
Dedicated VPS (per customer)
| Component | Cost |
|---|
| DigitalOcean droplet (4vCPU/8GB) | $48 |
| Managed Postgres (optional) | $15 |
| Backups | $10 |
| Domain + SSL | $0 |
| Total | ~$73 |
| Plan | Your Monthly Price | Infra Cost | Margin |
|---|
| SaaS Starter | ₦50,000 (~$33) | $5 (shared) | High |
| SaaS Growth | ₦150,000 (~$100) | $15 (shared) | High |
| SaaS Enterprise | ₦500,000 (~$333) | $50 (shared) | High |
| Dedicated VPS | ₦1,000,000 (~$667) | $73 | ~9× |
Recommendation: Start Here
- Month 1–3: Deploy SaaS on a single $48 DigitalOcean droplet
- Month 4–6: Onboard first 5–10 customers, monitor resource usage
- Month 6+: Split app and DB when CPU > 70% consistently
- Month 9+: Offer Dedicated VPS to your first enterprise customer
- Year 2: Move to managed services (Managed Postgres, Upstash, S3)
Do not offer Dedicated VPS until you have at least 5 SaaS customers paying consistently. The operational overhead of managing N separate servers is significant.
