# Custom Domain Support - Executive Summary

## What You Asked For

> "I want to deploy multiple shops on multiple different domains like domain1.com/shop1, domain2.com/shop2"

## What You Currently Have

Your FastAPI multi-tenant e-commerce platform currently supports:

1. **Subdomain routing** (production): `vendor1.platform.com` → Vendor 1
2. **Path-based routing** (development): `localhost:8000/vendor/vendor1/` → Vendor 1

## What's Missing

You **cannot** currently route custom domains like:
- `customdomain1.com` → Vendor 1
- `shop.mybrand.com` → Vendor 2

## The Solution

Add a **domain mapping table** that links custom domains to vendors:

```
customdomain1.com → Vendor 1
customdomain2.com → Vendor 2
```

Your middleware checks this table BEFORE checking subdomains.

## High-Level Architecture

### Current Flow
```
Customer → vendor1.platform.com → Middleware checks subdomain → Finds Vendor 1
```

### New Flow
```
Customer → customdomain1.com → Middleware checks domain mapping → Finds Vendor 1
```

### Priority Order (after implementation)
1. **Custom domain** (check `vendor_domains` table)
2. **Subdomain** (check `vendors.subdomain` - still works!)
3. **Path-based** (development mode - still works!)

## What Changes

### ✅ Changes Required

1. **Database**: Add `vendor_domains` table
2. **Model**: Create `VendorDomain` model
3. **Middleware**: Update to check custom domains first
4. **Config**: Add `platform_domain` setting

### ❌ What Stays the Same

- Existing subdomain routing (still works!)
- Path-based development routing (still works!)
- Vendor isolation and security
- All existing functionality
- API endpoints
- Admin panel

## Implementation Overview

### Database Schema
```sql
vendor_domains
├── id (PK)
├── vendor_id (FK → vendors.id)
├── domain (UNIQUE) - e.g., "customdomain1.com"
├── is_active
├── is_verified (prevents domain hijacking)
└── verification_token (for DNS verification)
```

### Middleware Logic
```python
def detect_vendor(request):
    host = request.host
    
    # NEW: Check if custom domain
    if not host.endswith("platform.com"):
        vendor = find_by_custom_domain(host)
        if vendor:
            return vendor
    
    # EXISTING: Check subdomain
    if is_subdomain(host):
        vendor = find_by_subdomain(host)
        return vendor
    
    # EXISTING: Check path
    if is_path_based(request.path):
        vendor = find_by_path(request.path)
        return vendor
```

## Real-World Example

### Vendor Setup Process

**Step 1: Admin adds domain**
- Admin logs in
- Navigates to Vendor → Domains
- Adds "customdomain1.com"
- Gets verification token: `abc123xyz`

**Step 2: Vendor configures DNS**
At their domain registrar (GoDaddy/Namecheap):
```
Type: A
Name: @
Value: 123.45.67.89 (your server IP)

Type: TXT
Name: _wizamart-verify
Value: abc123xyz
```

**Step 3: Verification**
- Wait 5-15 minutes for DNS propagation
- Admin clicks "Verify Domain"
- System checks DNS for TXT record
- Domain marked as verified ✓

**Step 4: Go Live**
- Customer visits `customdomain1.com`
- Sees Vendor 1's shop
- Everything just works!

## Technical Requirements

### Server Side
- **Nginx**: Accept all domains (`server_name _;`)
- **FastAPI**: Updated middleware
- **Database**: New table for domain mappings

### DNS Side
- Vendor points domain to your server
- A record: `@` → Your server IP
- Verification: TXT record for ownership proof

### SSL/TLS
Three options:
1. **Cloudflare** (easiest - automatic SSL)
2. **Let's Encrypt** (per-domain certificates)
3. **Wildcard** (subdomains only)

## Security

### Domain Verification
✅ Prevents domain hijacking
✅ Requires DNS TXT record
✅ Token-based verification
✅ Vendor must prove ownership

### Vendor Isolation
✅ All queries filtered by vendor_id
✅ No cross-vendor data leakage
✅ Middleware sets request.state.vendor
✅ Enforced at database level

## Benefits

### For Platform Owner (You)
- ✅ More professional offering
- ✅ Enterprise feature for premium vendors
- ✅ Competitive advantage
- ✅ Higher vendor retention
- ✅ Still maintain single codebase

### For Vendors
- ✅ Use their own brand domain
- ✅ Better SEO (own domain)
- ✅ Professional appearance
- ✅ Customer trust
- ✅ Marketing benefits

### For Customers
- ✅ Seamless experience
- ✅ Trust familiar domain
- ✅ No platform branding visible
- ✅ Better user experience

## Implementation Effort

### Minimal Changes
- **New table**: 1 table (`vendor_domains`)
- **New model**: 1 file (`vendor_domain.py`)
- **Updated middleware**: Modify existing file
- **Config**: Add 1 setting

### Time Estimate
- **Core functionality**: 4-6 hours
- **Testing**: 2-3 hours
- **Production deployment**: 2-4 hours
- **Total**: 1-2 days

### Risk Level
- **Low risk**: New feature, doesn't break existing
- **Backward compatible**: Old methods still work
- **Rollback plan**: Simple database rollback

## Testing Strategy

### Development Testing
```bash
# Add to /etc/hosts
127.0.0.1 testdomain.local

# Add test data
INSERT INTO vendor_domains (vendor_id, domain, is_verified)
VALUES (1, 'testdomain.local', true);

# Test
curl http://testdomain.local:8000/
```

### Production Testing
1. Add test domain for one vendor
2. Configure DNS
3. Verify detection works
4. Monitor logs
5. Roll out to more vendors

## Deployment Checklist

### Phase 1: Database
- [ ] Create migration
- [ ] Apply to development
- [ ] Test data insertion
- [ ] Apply to production

### Phase 2: Code
- [ ] Create model
- [ ] Update middleware
- [ ] Update config
- [ ] Deploy to development
- [ ] Test thoroughly
- [ ] Deploy to production

### Phase 3: Infrastructure
- [ ] Update Nginx config
- [ ] Test domain acceptance
- [ ] Configure SSL strategy
- [ ] Set up monitoring

### Phase 4: Launch
- [ ] Document vendor process
- [ ] Train admin team
- [ ] Test with pilot vendor
- [ ] Roll out gradually

## Monitoring & Maintenance

### Key Metrics
- Number of active custom domains
- Domain verification success rate
- Traffic per domain
- SSL certificate status
- Failed domain lookups

### Regular Tasks
- Review unverified domains (weekly)
- Check SSL certificates (monthly)
- Clean up inactive domains (quarterly)
- Monitor DNS changes (automated)

## Alternatives Considered

### ❌ Separate Deployments Per Vendor
- **Pros**: Complete isolation
- **Cons**: High maintenance, expensive, difficult to update
- **Verdict**: Not scalable

### ❌ Nginx-Only Routing
- **Pros**: No application changes
- **Cons**: Hard to manage, no database tracking, no verification
- **Verdict**: Not maintainable

### ✅ Database-Driven Domain Mapping (Recommended)
- **Pros**: Scalable, maintainable, secure, trackable
- **Cons**: Requires implementation effort
- **Verdict**: Best solution

## Success Criteria

- [ ] Can add custom domain via admin panel
- [ ] DNS verification works
- [ ] Custom domain routes to correct vendor
- [ ] Subdomain routing still works
- [ ] Path-based routing still works
- [ ] No cross-vendor data leakage
- [ ] SSL works on custom domains
- [ ] Monitoring in place
- [ ] Documentation complete

## ROI Analysis

### Costs
- Development: 1-2 days (one-time)
- Testing: 0.5 day (one-time)
- Maintenance: 1-2 hours/month

### Benefits
- Premium feature for enterprise vendors
- Higher vendor retention
- Competitive advantage
- Professional appearance
- Better vendor acquisition

### Break-Even
If even 5 vendors are willing to pay $50/month extra for custom domain feature:
- Revenue: $250/month = $3,000/year
- Cost: 2 days development ≈ $2,000
- **Break-even in ~8 months**

## Next Steps

### Immediate (This Week)
1. Review implementation guides
2. Test locally with demo domain
3. Verify approach with team

### Short-Term (This Month)
1. Implement database changes
2. Update middleware
3. Deploy to staging
4. Test with pilot vendor

### Long-Term (This Quarter)
1. Add admin UI
2. Document vendor process
3. Roll out to all vendors
4. Market as premium feature

## Resources Provided

### Documentation
1. **QUICK_START.md** - Get started in 30 minutes
2. **CUSTOM_DOMAIN_IMPLEMENTATION_GUIDE.md** - Complete guide
3. **ARCHITECTURE_DIAGRAMS.md** - Visual architecture
4. **IMPLEMENTATION_CHECKLIST.md** - Step-by-step tasks

### Code Files
1. **vendor_domain_model.py** - Database model
2. **updated_vendor_context.py** - Updated middleware
3. **vendor_domains_api.py** - Admin API endpoints
4. **migration_vendor_domains.py** - Database migration
5. **config_updates.py** - Configuration changes

## Questions & Answers

**Q: Will this break existing functionality?**
A: No! Subdomain and path-based routing still work. This adds a new layer on top.

**Q: What about SSL certificates?**
A: Recommend Cloudflare (automatic) or Let's Encrypt (per-domain). See full guide.

**Q: How do vendors point their domain?**
A: They add an A record pointing to your server IP. Simple DNS configuration.

**Q: What prevents domain hijacking?**
A: DNS verification via TXT record. Vendor must prove ownership before domain goes live.

**Q: Can one vendor have multiple domains?**
A: Yes! The `vendor_domains` table supports multiple domains per vendor.

**Q: What if vendor removes domain later?**
A: Just mark as `is_active = false` in database. Easy to deactivate.

**Q: Do I need separate servers per domain?**
A: No! Single server accepts all domains. Middleware routes to correct vendor.

## Conclusion

**Is your current architecture capable?**
✅ Yes! Your multi-tenant architecture is perfect for this.

**What needs to change?**
✅ Minimal changes: 1 table, 1 model, middleware update

**Is it worth it?**
✅ Yes! Enterprise feature, competitive advantage, premium pricing

**Risk level?**
✅ Low! Backward compatible, rollback-friendly

**Implementation complexity?**
✅ Medium! 1-2 days for experienced FastAPI developer

**Recommendation:**
✅ **GO FOR IT!** This is a valuable feature that fits naturally into your architecture.

---

**Ready to start?** Begin with `QUICK_START.md` for a 30-minute implementation!
