EC2 Pricing Models comparison.

In Simple Words:

• On-Demand: Pay by the second with zero commitment. Most expensive.
• Savings Plans / Reserved Instances: 1- or 3-year commitment for steady workloads; up to 72% discount.
• Spot Instances: Spare AWS capacity with up to 90% discount. AWS can reclaim instances with a 2-minute warning. Great for fault-tolerant batch workers and CI/CD runners.

# EC2 Launch Template requesting Spot Instances:
resource "aws_launch_template" "worker" {
  instance_market_options {
    market_type = "spot"
    spot_options {
      max_price = "0.05"
      spot_instance_type = "one-time"
    }
  }
}