cf-ssm-parameters-ami.yml

# read more at: https://docs.aws.amazon.com/systems-manager/latest/userguide/parameter-store-public-parameters.html


# this will pickup the latest value of the parameter every time the template is run
# the parameter value must be the Key for that Parameter. Then CFN will retrieve the value
# this does not support SecureString SSM Parameter types
Parameters:
  LatestLinuxAmiId:
    Type: 'AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>'
    # obtain list with
    # aws ssm get-parameters-by-path --path /aws/service/ami-amazon-linux-latest  --query 'Parameters[].Name'
    Default: '/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2'

  # this works for Windows too
  LatestWindowsAmiId:
    Type: 'AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>'
    # obtain list with
    # aws ssm get-parameters-by-path --path "/aws/service/ami-windows-latest" --region us-east-1
    Default: '/aws/service/ami-windows-latest/Windows_Server-2016-English-Core-Base'

Resources:
  # this instance will be automatically updated 
  # when AWS releases a new AMI
  # and then run the CloudFormation template
  MyInstanceWithParameters:
    Type: AWS::EC2::Instance
    Properties:
      ImageId: !Ref LatestLinuxAmiId
      InstanceType: t2.micro