CloudFormation - Declarative code example in YAML

ec2-if-env-is-prod.yml

Parameters:
  LargerInstance:
    Description: Whether a larger instance should be used
    Default: false
    Type: String
    AllowedValues: [true, false]
Resources:
  EC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      InstanceType:
        !If [UseLargerInstance, m4.large, t2.micro]
      KeyName: 'default' # keypair must already exist
      ImageId: ami-8c1be5f6 # AMI us-east-1
Conditions:
  UseLargerInstance: !Equals [true, !Ref LargerInstance]