GCP network design for a E-Commerce Application

1️⃣ Start with the high-level architecture (what we’re aiming for)

Before touching GCP consoles, you need a mental model:

• Public edge: Users → Load Balancer → Web/App

• Private core: APIs, databases, caches

• Controlled egress: Outbound traffic locked down

• Strong isolation: Prod ≠ staging ≠ dev

2️⃣ Project & environment strategy (don’t skip this)

Best practice for e-commerce:

Why

• Billing isolation

• IAM blast-radius control

• Easy teardown of non-prod

⚠️ Mistake to avoid: Multiple environments in one project → painful IAM & firewall rules later.

3️⃣ Design the VPC (your network backbone)

Create one custom VPC per environment.

Example VPC

Subnet layout (regional, not zonal)

Why this matters for e-commerce

• Limits PCI scope

• Easier firewall rules

• Clear traffic flows for audits

4️⃣ Internet access: ingress & egress done right

Ingress (users → app)

• Global HTTP(S) Load Balancer

• Cloud Armor (WAF + DDoS)

• Managed SSL certs

Flow:

Egress (app → internet)

• Cloud NAT for private subnets

• No public IPs on backend services

⚠️ E-commerce rule of thumb:
If it doesn’t need inbound traffic, it should NOT have a public IP.

5️⃣ Web & application tier

Web tier options

• Cloud Run (best for modern e-commerce)

• GKE (if you need heavy customization)

• Compute Engine (legacy / special cases)

Typical setup

• Cloud Run services in private-app subnet

• Serverless NEG attached to Load Balancer

• Auto-scaling for sales spikes

Why Cloud Run shines

• Handles Black Friday spikes automatically

• Pay-per-use

• No node management

6️⃣ API & internal service communication

Use private, internal networking only.

• Internal HTTPS load balancer

• Service-to-service auth (IAM / IAP)

• No east-west traffic over public internet

This keeps:

• Checkout APIs

• Inventory services

• Payment orchestration

fully private.

7️⃣ Data layer (most sensitive part)

Typical e-commerce stack

• Cloud SQL (orders, users)

• Firestore / Bigtable (catalog, sessions)

• Memorystore (Redis) (cart, cache)

Networking rules

• Private IP only

• Located in private-data subnet

• Firewall: only app subnet allowed

🔐 Bonus: Enables easier PCI & SOC2 compliance.

8️⃣ Firewall rules (zero trust mindset)

Sample rules

Tips

• Use tags or service accounts, not IPs

• Start restrictive, open only when needed

9️⃣ Hybrid & external integrations

For payment gateways, ERP, or on-prem systems:

• Cloud VPN (fast start)

• Cloud Interconnect (high volume)

• Private Service Connect for SaaS

🔟 Observability & security (production-grade)

Must-haves:

• VPC Flow Logs

• Cloud Logging & Monitoring

• Cloud Armor WAF rules

• Security Command Center

E-commerce insight
Most attacks hit:

• /checkout

• /login

• /cart

Tune WAF rules specifically for these paths.

🧠 Final traffic flow (end-to-end)