lambda

Two questions settle most of it: how much of the machine do you want to own, and is the workload request-shaped or long-running. Fargate is a way of running containers rather than a competitor to ECS and EKS, which is the distinction people get wrong.

Most candidates can sell serverless. The question asks you to argue against it, which needs a real understanding of the execution model rather than the marketing.

Rapid function scaling can overwhelm a shared dependency. Concurrency limits, reserved capacity and queue buffering are the containment toolkit.

Postgres spends memory on a backend process per connection, and serverless fan-out treats that as an invitation. Pooling at the proxy layer is the standard cure; pinning is the catch.

Pay-per-use sounds free until the invoice arrives. The useful method is to decompose the bill into invocations, gigabyte-seconds and the lines nobody models, then locate the honest crossover rather than arguing about it.