DevOps Professional · Module 8: Architecture decisions and defense · Lab
Compare Three Designs Under Given Constraints and Choose
50 min hands-on · Core
A local machine; no cluster needed. Fixture context (labeled fictional): shop BrightCart, 5k orders/day, 3x holiday peak, card data in scope, two engineers on call. Design exercise, no terminal required.
Local guide: run the steps below on your own machine in order, then check the validation list.
Objectives
- Score all three designs on security, cost and reliability with shared numbers
- Choose with the trade-offs stated and the gaps listed
- Record deciders and revisit triggers
Step 1
Score on shared numbers
Use this shared constraint sheet (fictional): peak 60 orders/min, p95 checkout under 2s, card data encrypted at rest plus TLS in transit, monthly infra budget 900 USD, recovery under 30 min. Designs: A single VM plus managed database (simple, cheap, single failure domain); B two VMs behind a load balancer plus managed database with read replica (balanced); C Kubernetes with three nodes plus managed database (operational cost highest). Score each design 1 to 5 on security, cost and reliability under identical traffic and growth assumptions. Quote the three-axis table; no axis skipped, no design spared.
Step 2
Choose with gaps listed
Pick the fitting design for the fixture context and list its gaps openly (what it concedes on each axis). Write why the others lost with numbers, not adjectives.
Step 3
Record the balance
Record deciders, the chosen balance with its numbers, and a revisit trigger per axis. State the no-claim rule: fit for this context, not one right answer.
How to confirm it worked
- Three-axis table quoted with shared assumptions
- Choice with openly listed gaps and numeric reasons
- Deciders and per-axis revisit triggers recorded