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Drop 3 – DIY CDN: Serving shoppers from 50 feet away Part of the LinkedIn series “Edge Renaissance: putting compute—and the customer—back where they belong.”
☕ Executive espresso (60‑second read)
- **Why bother? ** Third‑party CDNs still push requests hundreds of miles; your stores already sit next to the customer. Turn each three‑node Proxmox cluster into a micro‑PoP and you cut the round‑trip by up to 180 ms—the difference between “meh” and magic.
- Speed sells. Akamai found a 100 ms delay dents conversions by 7 % (Akamai), while Google / Deloitte showed a 0.1‑second boost lifts retail conversions 8.4 % and AOV 9.2 % (Google Business).
- Own the edge, own the margin. Commercial CDNs bill ~$0.04‑$0.05/GB at scale (Akamai calculator, 2025) (BlazingCDN Blog) and even small‑plan Cloudflare traffic costs $1/GB after miniscule free tiers (Cloudflare). In‑store delivery rides bandwidth you’re already paying for.
Bottom line: a private, location‑aware CDN isn’t a science project—it’s “back to basics” Internet architecture that converts better and costs less.
1 Why roll your own instead of renting a PoP?
| Question senior execs ask | Third‑party CDN answer | Retail‑edge answer |
|---|---|---|
| How fast can we get? | 40‑200 ms (public PoP → origin) | < 30 ms TTFB—cluster is in the building |
| Who keeps the data? | TLS keys & logs sit off‑prem | Everything stays in your closet |
| What’s the true cost? | Pay per GB forever + egress back to origin | One‑time cap‑ex; incremental $0 |
2 Anatomy of a Retail Edge Delivery Network (REDN)
[ Shopper’s phone ] ←Wi‑Fi / LTE→ [ Store closet ]
├── Varnish / Nginx (static cache)
├── WASM / Lua FX (per‑request logic)
├── KVM / LXC (POS, inventory API)
└── Ceph pool (replicated assets)
↑ nightly diff
[ S3 DR bucket ] ← WireGuard mesh →
One shoebox‑sized cluster wears two hats: it runs operational apps and serves front‑end assets + edge functions. No extra licences, no extra racks.
3 What “50 feet away” feels like to the customer
| Scenario | Traditional path | REDN path | Result |
|---|---|---|---|
| Product image on PDP | Phone → CDN PoP (300 mi) → Origin → Back | Phone → In‑store cache | Image paints 5‑10× faster |
| “Pick up in 30 min?” badge | PDP JS → Cloud API → ERP | PDP JS → /inventory API on closet |
Real‑time stock, no spinner |
| Vision‑AI loss prevention alert | Camera stream to cloud | GPU container on cluster | Sub‑50 ms alert, zero egress |
4 Cost lens (after you bank the CX upside)
| Variable cost on 100 TB/mo | Commercial CDN | REDN |
|---|---|---|
| Transfer fees | 100 TB × $0.045 = $4.5 k (BlazingCDN Blog) | $0 (uses store uplink) |
| Cloud egress to origin | 10 TB × $0.09 = $900 (typ. AWS) | $0–$50 (delta sync) |
| TLS key escrow | Enterprise add‑on | N/A (you hold keys) |
Hardware amortised over 4 yrs = <$105/mo per store; ROI < 18 months.
5 Build‑it‑this‑week blueprint
-
Add a CDN role to the existing Proxmox cluster:
pct create 1300 varnish-template --net0 name=eth0,bridge=vmbr0,ip=dhcp -
Pin assets on the Ceph pool (
/ceph/cdn). -
Deploy edge function (promo injector) via containerised WASM runtime.
-
Publish GeoDNS—
cdn.example.comresolves to store IP ranges, with a fallback to an S3‑backed origin. -
Wire nightly sync: Proxmox Backup Server δ‑snapshots to a central bucket for DR.
6 Customer‑obsessed use‑cases to steal today
- Hyper‑local promos: Edge function reads loyalty cookie + on‑hand stock, swaps hero banner only if the item is actually in aisle 7.
- AR try‑on textures: 4K assets live in the closet; shoppers on store Wi‑Fi stream instantly.
- Real‑time order status: BOPIS app hits a μ‑service next to the pick‑pack robots, not a far‑off DC.
- Zero‑downtime kiosks: Even if the ISP blips, cached JS + local APIs keep self‑checkout humming.
Coming up next ➡️ “Edge Workloads That Win Hearts (and Wallets).”
We’ll dive into the AI vision, robotics, and inventory apps that turn this infrastructure into a true competitive moat.
Stay subscribed—your customers, and your CFO, will thank you.