In one sentence
Choose EC2 for host control, Lambda for short event-driven functions, and Fargate for serverless container tasks.
Key points
- EC2 gives operating-system control and supports long-running or specialized workloads, but requires instance management.
- Lambda automatically scales short functions and bills by invocation and duration, with a 15-minute maximum.
- Fargate runs containers without managing servers but still needs ECS or EKS orchestration.
Exam takeaway
Decide by deployment unit, runtime duration, host control, scaling pattern, and operational responsibility.
Additional decision dimensions
- Need a full OS, specialized hardware, daemons, or workloads beyond platform limits → EC2.
- Event-driven work of at most 15 minutes with concurrency-based scaling → Lambda; still design for cold starts and downstream capacity.
- Existing container images and long-running tasks without node operations → Fargate, orchestrated by ECS or EKS.
- Stable scale, specialized nodes, GPUs, or stronger cost control may favor ECS/EKS on EC2.