$ aws cloudformation validate-template --template-body file:///home/bhemanth/Downloads/ec2-templates/singe-instance-v2.yaml

An error occurred (ValidationError) when calling the ValidateTemplate operation: Invalid template resource property 'BlockDeviceMappings'

AWSTemplateFormatVersion: '2010-09-09'
Description: 'CentOS EC2 Instance template'
Parameters:
  KeyName:
    Description: Name of an existing EC2 KeyPair to enable SSH access to the instance
    Type: AWS::EC2::KeyPair::KeyName
    Default: hemanth
    AllowedValues:
    - hemanth
    - client
    ConstraintDescription: must be the name of an existing EC2 KeyPair.
  InstanceType:
    Description: CentOS
    Type: String
    Default: t2.small
    AllowedValues:
    - t2.micro
    - t2.small
    - t2.medium
    ConstraintDescription: must be a valid EC2 instance type.
  SSHLocation:
    Description: The IP address range that can be used to SSH to the EC2 instances
    Type: String
    MinLength: '9'
    MaxLength: '18'
    Default: 0.0.0.0/0
    AllowedPattern: "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})/(\\d{1,2})"
    ConstraintDescription: must be a valid IP CIDR range of the form x.x.x.x/x.
Resources:
  EC2Instance:
    Type: AWS::EC2::Instance
    Properties:
      InstanceType:
        Ref: InstanceType
      SecurityGroups:
      - Ref: InstanceSecurityGroup
      KeyName:
        Ref: KeyName
      ImageId: ami-01ed306a12b7d1c96
  InstanceSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupName: EnableAll
      GroupDescription: Enable SSH access for all ports
      SecurityGroupIngress:
      - IpProtocol: tcp
        FromPort: '0'
        ToPort: '65535'
        CidrIp:
          Ref: SSHLocation
    BlockDeviceMappings:
    - DeviceName: /dev/sda1
      Ebs:
        DeleteOnTermination: true
        Status: attached
    Hypervisor: xen
    RootDeviceName: /dev/sda1
    RootDeviceType: ebs
    Tags:
    - Key: Name
      Value: Docker
    VirtualizationType: hvm
    UserData:
      Fn::Base64: !Sub |
        #!/usr/bin/env bash
        yum install -y wget
        wget -O- https://get.docker.com/ | sh
        systemctl status docker
        systemctl start docker
        systemctl enable docker
        systemctl status docker
        systemctl status -l docker
    Volumes:
    - Attachments:
        Device: /dev/sda1
        State: attached
        DeleteOnTermination: true
      AvailabilityZone: us-west-2a
      Encrypted: false
      Size: 30
      State: in-use
      Iops: 100
      VolumeType: gp2
Outputs:
  InstanceId:
    Description: InstanceId of the newly created EC2 instance
    Value:
      Ref: EC2Instance
  AZ:
    Description: Availability Zone of the newly created EC2 instance
    Value:
      Fn::GetAtt:
      - EC2Instance
      - AvailabilityZone
  PublicDNS:
    Description: Public DNSName of the newly created EC2 instance
    Value:
      Fn::GetAtt:
      - EC2Instance
      - PublicDnsName
  PublicIP:
    Description: Public IP address of the newly created EC2 instance
    Value:
      Fn::GetAtt:
      - EC2Instance
      - PublicIp