**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][1]), while Google / Deloitte showed a 0.1‑second boost lifts retail conversions **8.4 %** and AOV **9.2 %** ([Google Business][2]). * **Own the edge, own the margin.** Commercial CDNs bill \~\$0.04‑\$0.05/GB at scale (Akamai calculator, 2025) ([BlazingCDN Blog][3]) and even small‑plan Cloudflare traffic costs **\$1/GB** after miniscule free tiers ([Cloudflare][4]). 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][3]) | **\$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 1. **Add a CDN role** to the existing Proxmox cluster: ```bash pct create 1300 varnish-template --net0 name=eth0,bridge=vmbr0,ip=dhcp ``` 2. **Pin assets** on the Ceph pool (`/ceph/cdn`). 3. **Deploy edge function** (promo injector) via containerised WASM runtime. 4. **Publish GeoDNS**—`cdn.example.com` resolves to store IP ranges, with a fallback to an S3‑backed origin. 5. **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.* [1]: https://www.akamai.com/newsroom/press-release/akamai-releases-spring-2017-state-of-online-retail-performance-report?utm_source=chatgpt.com "Akamai Online Retail Performance Report: Milliseconds Are Critical" [2]: https://www.thinkwithgoogle.com/_qs/documents/9757/Milliseconds_Make_Millions_report_hQYAbZJ.pdf?utm_source=chatgpt.com "[PDF] Milliseconds Make Millions - Think with Google" [3]: https://blog.blazingcdn.com/en-us/akamai-cdn-cost-calculator-2025 "Akamai Content Delivery Network CDN Cost Calculator for 2025" [4]: https://www.cloudflare.com/plans/?utm_source=chatgpt.com "Our Plans | Pricing - Cloudflare"