An image-resizing routine runs for about two seconds whenever a file lands in a storage container — perhaps two hundred times on a busy day, and not at all on a quiet one. The team wants to pay for the work done and maintain no servers. Which compute option fits?
Microsoft Certified: Azure Fundamentals (AZ-900), objective architecture-and-services. Azure architecture and services medium
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The options
Correct Azure Functions on a consumption plan
Correct. Functions runs code in response to an event, scales down to nothing when no events arrive, and bills for executions and the resources they consume — which is the exact shape of a bursty, idle-most-of-the-time workload.
Not correct A virtual machine sized for the busiest hour, left running
Wrong. It bills for every hour it exists, busy or idle, so the quiet days are paid for in full — and you have also taken on patching an operating system to run two seconds of code.
Not correct An Azure Kubernetes Service cluster with an autoscaling node pool
Wrong for this shape of work. Kubernetes can certainly run it, but you have acquired a cluster to operate for a two-second routine, and the node pool has a minimum size, so there is a standing bill on the quiet days.
Not correct A Virtual Machine Scale Set with autoscale rules
Wrong. Scale sets adjust a fleet of virtual machines against metrics such as CPU. They react over minutes, normally keep at least one instance running, and still leave you the operating system to look after.
Why
Serverless in Azure means three things together: no infrastructure for you to manage, automatic scaling driven by demand, and billing tied to execution rather than to uptime. That third property is the discriminator on this exam — if a workload is event-driven and idle most of the time, the winning answer is almost always the one that can bill nothing when nothing is happening.
Where this comes from
- Cited
- Microsoft AZ-900 study guide skill area architecture-and-services.compute-and-networking
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