What should a solutions architect recommend?
Use Amazon EC2 Auto Scaling to scale at certain periods based on previous traffic patterns.
Use an AWS Lambda function to scale Amazon ECS based on metric breaches that trigger an Amazon CloudWatch alarm.
Use Amazon EC2 Auto Scaling with simple scaling policies to scale when ECS metric breaches trigger an Amazon CloudWatch alarm.
Use AWS Application Auto Scaling with target tracking policies to scale when ECS metric breaches trigger an Amazon CloudWatch alarm.
Explanations:
Amazon EC2 Auto Scaling is not applicable when using the Fargate launch type, as Fargate manages the infrastructure, and tasks are scaled based on the task definitions rather than EC2 instances.
Using an AWS Lambda function for scaling is not a direct method supported by ECS Fargate. While Lambda can be used for triggering actions, it does not provide a scalable solution for managing ECS tasks based on CloudWatch alarms without a more integrated approach.
Amazon EC2 Auto Scaling is not suitable for Fargate, as it relies on managing EC2 instances. Fargate abstracts away the infrastructure, and therefore EC2 Auto Scaling cannot be applied.
AWS Application Auto Scaling with target tracking policies is specifically designed for services like ECS running on Fargate. It allows for automatic scaling of ECS services based on CloudWatch metrics, making it ideal for managing costs during variable traffic.
I think the answer is:
Use AWS Application Auto Scaling with target tracking policies to scale when ECS metric breaches trigger an Amazon CloudWatch alarm.