Default BlockDeviceMappings settings for AutoScaling::LaunchConfiguration

Question

We are using CloudFormation to create an EC2 machine using AWS::AutoScaling::LaunchConfiguration, but we never really specified the BlockDeviceMapping to use:

Type: AWS::AutoScaling::LaunchConfiguration
Properties: 
  AssociatePublicIpAddress: 'false'
  ImageId: 'some-image-id'
  InstanceType: 'some-instance-type (e.g. t2.large)' 
  KeyName: String
  SecurityGroups: 'some-security-group'
  IamInstanceProfile: 'some-iam-instance-profile'
  UserData: 'some commands to execute'

The official documentation states that the BlockDeviceMappings are not required, but it does not state what the default value will be when we do not specify one.

What will be the default EBS created when the BlockDeviceMappings property is not filled in?

Answer 1

If not specified, the default value will be the mapping specified in the AMI used in the launch template, as specified on the documentation page for AWS::EC2::Instance.