01 The challenge
Every peak campaign was a gamble: the platform could not scale horizontally, caching was minimal, and the checkout shared a database with everything else. Marketing had to throttle campaigns to what the site could survive, and the cost of every outage was measured in lost weekend revenue.
02 What we did
- Incremental decomposition of the monolith — catalogue, search, cart and checkout separated into independently scalable services
- Edge caching and CDN for catalogue and content, with a fast headless storefront
- Checkout hardening: queueing, idempotent payments and isolated data stores
- Auto-scaling cloud infrastructure with load tests at multiples of previous peak
- Observability and campaign war-room runbooks for peak weekends
03 The results
- Concurrent-user capacity increased by more than an order of magnitude
- Checkout abandonment fell to a fraction of its previous level
- Page load times brought to around a second
- A record campaign weekend processed without incident