For this setup, do the following: 1.    Create a custom AWS Identity and Access Management (IAM) policy and execution role for your Lambda function. 2.    Create Lambda functions that stop and start your EC2 instances. 3.    Create CloudWatch Events rules that trigger your function on a schedule. For example, you could create a rule to stop your EC2 instances at night, and another to start them again in the morning.

If you wish to run more than 20 On-Demand instances, complete the Amazon EC2 instance request form.