Domain Management Skill

This skill helps you manage domains and DNS configuration for the SG Cars Trends platform.

When to Use This Skill

• Adding new subdomains
• Configuring SSL certificates
• Updating DNS records
• Debugging domain resolution issues
• Setting up custom domains for services
• Managing Cloudflare settings
• Troubleshooting SSL/TLS errors

Domain Architecture

Domain Structure

sgcarstrends.com                    # Production web app
staging.sgcarstrends.com            # Staging web app
dev.sgcarstrends.com                # Development web app

api.sgcarstrends.com                # Production API
api.staging.sgcarstrends.com        # Staging API
api.dev.sgcarstrends.com            # Development API

admin.sgcarstrends.com              # Admin app (future)
docs.sgcarstrends.com               # Documentation (future)

Naming Convention

Web Apps:

• Production: Apex domain (sgcarstrends.com)
• Other envs: {stage}.sgcarstrends.com

Backend Services:

• Pattern: {service}.{stage}.sgcarstrends.com
• Production service: {service}.sgcarstrends.com (no stage prefix)

Examples:

api.sgcarstrends.com              # Production API
api.staging.sgcarstrends.com      # Staging API
websocket.sgcarstrends.com        # Production WebSocket service
websocket.dev.sgcarstrends.com    # Dev WebSocket service

DNS Provider: Cloudflare

Why Cloudflare?

• Free SSL certificates
• DDoS protection
• CDN capabilities
• Fast DNS propagation
• Analytics and logs
• Page Rules for optimization

DNS Management

Cloudflare manages DNS records, AWS Route53 is for SSL certificate validation only.

SST Domain Configuration

DNS Stack

// infra/dns.ts
import { StackContext } from "sst/constructs";
import * as route53 from "aws-cdk-lib/aws-route53";

export function DNS({ stack }: StackContext) {
  // Import existing hosted zone (created in Route53)
  const hostedZone = route53.HostedZone.fromLookup(stack, "HostedZone", {
    domainName: "sgcarstrends.com",
  });

  stack.addOutputs({
    HostedZoneId: hostedZone.hostedZoneId,
    HostedZoneName: hostedZone.zoneName,
  });

  return { hostedZone };
}

Web App Domain

// infra/web.ts
import { StackContext, NextjsSite, use } from "sst/constructs";
import { DNS } from "./dns";

export function Web({ stack, app }: StackContext) {
  const { hostedZone } = use(DNS);

  const web = new NextjsSite(stack, "web", {
    path: "apps/web",
    customDomain: {
      domainName: app.stage === "production"
        ? "sgcarstrends.com"                    // Apex domain for prod
        : `${app.stage}.sgcarstrends.com`,       // Subdomain for others
      hostedZone: hostedZone.zoneName,
    },
  });

  stack.addOutputs({
    WebUrl: web.url,
    WebDomain: web.customDomainUrl,
  });

  return { web };
}

API Domain

// infra/api.ts
import { StackContext, Function, use } from "sst/constructs";
import { DNS } from "./dns";

export function API({ stack, app }: StackContext) {
  const { hostedZone } = use(DNS);

  const api = new Function(stack, "api", {
    handler: "apps/api/src/index.handler",
    url: {
      domain: {
        domainName: app.stage === "production"
          ? "api.sgcarstrends.com"
          : `api.${app.stage}.sgcarstrends.com`,
        hostedZone: hostedZone.zoneName,
      },
    },
  });

  stack.addOutputs({
    ApiUrl: api.url,
    ApiDomain: api.url,
  });

  return { api };
}

Cloudflare Configuration

DNS Records

Cloudflare DNS records point to AWS CloudFront or Lambda Function URLs:

Type    Name                     Value                                   Proxy
CNAME   sgcarstrends.com        d111111abcdef8.cloudfront.net          ✓ Proxied
CNAME   staging                 d222222abcdef8.cloudfront.net          ✓ Proxied
CNAME   dev                     d333333abcdef8.cloudfront.net          ✓ Proxied
CNAME   api                     abc123.lambda-url.ap-southeast-1.on.aws  ✓ Proxied
CNAME   api.staging             def456.lambda-url.ap-southeast-1.on.aws  ✓ Proxied

SSL/TLS Settings

Encryption Mode: Full (strict)

• Encrypts traffic from browser to Cloudflare
• Encrypts traffic from Cloudflare to origin (AWS)
• Validates origin certificate

Edge Certificates:

• Automatically provisioned by Cloudflare
• Covers *.sgcarstrends.com and sgcarstrends.com
• Auto-renewed

Page Rules

Rule 1: Cache API responses
URL: api.sgcarstrends.com/*
Settings:
  - Cache Level: Standard
  - Edge Cache TTL: 1 hour

Rule 2: Always use HTTPS
URL: *sgcarstrends.com/*
Settings:
  - Always Use HTTPS: On

Rule 3: Security headers
URL: sgcarstrends.com/*
Settings:
  - Security Headers: On
  - HSTS: Enabled

SSL Certificate Management

AWS Certificate Manager

SST automatically requests certificates from ACM:

// Automatic when using customDomain
const web = new NextjsSite(stack, "web", {
  customDomain: {
    domainName: "sgcarstrends.com",
    hostedZone: hostedZone.zoneName,
  },
});

// SST will:
// 1. Request certificate from ACM
// 2. Add DNS validation records to Route53
// 3. Wait for validation
// 4. Attach certificate to CloudFront/Lambda

Manual Certificate Request

If needed:

# Request certificate
aws acm request-certificate \
  --domain-name sgcarstrends.com \
  --subject-alternative-names *.sgcarstrends.com \
  --validation-method DNS \
  --region us-east-1  # CloudFront requires us-east-1

# Get validation records
aws acm describe-certificate \
  --certificate-arn arn:aws:acm:... \
  --region us-east-1

Add validation CNAME records to Cloudflare DNS.

Adding New Subdomains

1. Define in SST

// infra/new-service.ts
import { StackContext, Function, use } from "sst/constructs";
import { DNS } from "./dns";

export function NewService({ stack, app }: StackContext) {
  const { hostedZone } = use(DNS);

  const service = new Function(stack, "new-service", {
    handler: "apps/new-service/src/index.handler",
    url: {
      domain: {
        domainName: app.stage === "production"
          ? "newservice.sgcarstrends.com"
          : `newservice.${app.stage}.sgcarstrends.com`,
        hostedZone: hostedZone.zoneName,
      },
    },
  });

  return { service };
}

2. Deploy

npx sst deploy --stage production

SST will:

1. Request ACM certificate
2. Create Route53 records for validation
3. Wait for validation
4. Create Lambda Function URL or CloudFront distribution
5. Output the AWS resource URL

3. Add Cloudflare DNS

Get the AWS URL from SST outputs, then:

1. Go to Cloudflare dashboard
2. Select sgcarstrends.com domain
3. Click "DNS" → "Add record"
4. Type: CNAME
5. Name: newservice (or newservice.staging)
6. Target: The AWS URL (CloudFront or Lambda)
7. Proxy status: Proxied (orange cloud)
8. TTL: Auto
9. Save

4. Verify

# Check DNS resolution
dig newservice.sgcarstrends.com

# Test HTTPS
curl -I https://newservice.sgcarstrends.com

Debugging DNS Issues

Check DNS Propagation

# Check Cloudflare DNS
dig @1.1.1.1 sgcarstrends.com
dig @1.1.1.1 api.sgcarstrends.com

# Check global propagation
dig sgcarstrends.com @8.8.8.8  # Google DNS
dig sgcarstrends.com @1.1.1.1  # Cloudflare DNS

# Or use online tools
# https://www.whatsmydns.net/#CNAME/api.sgcarstrends.com

Check SSL Certificate

# Check certificate details
openssl s_client -connect sgcarstrends.com:443 -servername sgcarstrends.com

# Check certificate expiry
echo | openssl s_client -connect sgcarstrends.com:443 -servername sgcarstrends.com 2>/dev/null | openssl x509 -noout -dates

Test Domain Resolution

# Test HTTP → HTTPS redirect
curl -I http://sgcarstrends.com

# Test HTTPS
curl -I https://sgcarstrends.com

# Test API endpoint
curl -I https://api.sgcarstrends.com/health

Common Issues

Issue: DNS not resolving Solutions:

1. Check Cloudflare DNS record exists
2. Verify record type (CNAME vs A)
3. Check proxy status (should be Proxied)
4. Wait for propagation (usually < 5 minutes)

Issue: SSL certificate error Solutions:

1. Check Cloudflare SSL mode is "Full (strict)"
2. Verify ACM certificate is issued
3. Check certificate covers the subdomain
4. Verify Route53 has validation records

Issue: 522 error (Connection timed out) Solutions:

1. Check Lambda/CloudFront is running
2. Verify security groups allow HTTPS
3. Check origin server is responding
4. Review Cloudflare → Origin connection

Issue: Redirecting to wrong domain Solutions:

1. Check SST customDomain configuration
2. Verify Cloudflare page rules
3. Check application redirect logic

CORS Configuration

When API and Web are on different domains:

// apps/api/src/index.ts
import { Hono } from "hono";
import { cors } from "hono/cors";

const app = new Hono();

app.use("/*", cors({
  origin: [
    "https://sgcarstrends.com",
    "https://staging.sgcarstrends.com",
    "https://dev.sgcarstrends.com",
    "http://localhost:3001",  // Local development
  ],
  credentials: true,
}));

Monitoring

Cloudflare Analytics

1. Go to Cloudflare dashboard
2. Select domain
3. Click "Analytics & Logs"

View:

• Traffic stats
• Performance metrics
• Security events
• Cache analytics

AWS Route53 Health Checks

// infra/monitoring.ts
import { StackContext } from "sst/constructs";
import * as route53 from "aws-cdk-lib/aws-route53";

export function Monitoring({ stack }: StackContext) {
  new route53.CfnHealthCheck(stack, "ApiHealthCheck", {
    healthCheckConfig: {
      type: "HTTPS",
      fullyQualifiedDomainName: "api.sgcarstrends.com",
      port: 443,
      resourcePath: "/health",
      requestInterval: 30,
      failureThreshold: 3,
    },
  });
}

Domain Migration

Migrating to New Domain

1. Set up new domain in Cloudflare
2. Deploy to new domain:

   customDomain: {
     domainName: "new-domain.com",
     hostedZone: newHostedZone.zoneName,
   }
   

3. Test new domain thoroughly
4. Set up redirects from old to new:

   // Cloudflare page rule
   URL: old-domain.com/*
   Forwarding URL: 301 - https://new-domain.com/$1
   

5. Update all references
6. Monitor traffic
7. Keep old domain for 6-12 months

Apex Domain Considerations

Using Apex Domain

The project uses apex domain (sgcarstrends.com) for production:

Advantages:

• Shorter, cleaner URL
• Better for branding
• SEO benefits

Challenges:

• CNAME at apex not allowed by DNS spec
• Solution: Cloudflare CNAME flattening

Cloudflare CNAME Flattening

Cloudflare automatically flattens CNAMEs at apex:

# This works with Cloudflare:
CNAME  sgcarstrends.com  →  d111111abcdef8.cloudfront.net

# Cloudflare resolves it to:
A      sgcarstrends.com  →  104.21.x.x
A      sgcarstrends.com  →  172.67.x.x

Subdomain Strategy

Current Subdomains

Web apps:
  sgcarstrends.com           # Production
  staging.sgcarstrends.com   # Staging
  dev.sgcarstrends.com       # Development

API:
  api.sgcarstrends.com       # Production
  api.staging...             # Staging
  api.dev...                 # Development

Future:
  admin.sgcarstrends.com     # Admin panel
  docs.sgcarstrends.com      # Documentation
  status.sgcarstrends.com    # Status page

Adding Future Services

Follow the pattern:

• Production: {service}.sgcarstrends.com
• Non-production: {service}.{stage}.sgcarstrends.com

Security Headers

Configure in Cloudflare or application:

// apps/web/next.config.js
const securityHeaders = [
  {
    key: "X-DNS-Prefetch-Control",
    value: "on",
  },
  {
    key: "Strict-Transport-Security",
    value: "max-age=63072000; includeSubDomains; preload",
  },
  {
    key: "X-Frame-Options",
    value: "SAMEORIGIN",
  },
  {
    key: "X-Content-Type-Options",
    value: "nosniff",
  },
  {
    key: "Referrer-Policy",
    value: "origin-when-cross-origin",
  },
];

const nextConfig = {
  async headers() {
    return [
      {
        source: "/:path*",
        headers: securityHeaders,
      },
    ];
  },
};

References

• Cloudflare Docs: https://developers.cloudflare.com
• AWS Route53: https://docs.aws.amazon.com/route53
• SST Custom Domains: https://docs.sst.dev/custom-domains
• Related files:
  • infra/dns.ts - DNS configuration
  • infra/CLAUDE.md - Infrastructure documentation

Best Practices

1. Use Cloudflare Proxy: Enable orange cloud for DDoS protection
2. Full (Strict) SSL: Always use strict SSL mode
3. HTTPS Only: Enforce HTTPS with page rules
4. Consistent Naming: Follow {service}.{stage}.domain pattern
5. Certificate Management: Let SST handle ACM certificates
6. DNS TTL: Use Auto for active development, higher for stable
7. Monitoring: Set up health checks for critical domains
8. Documentation: Document all subdomains and their purpose