Mounting multiple BlockDeviceMappings to an EC2 instance using Cloudformation

Question

I'm trying to mount multiple EBS volumes to my EC2 instance using cloudformation, but for some reason, only the last EBS volume that I specify gets mounted.

EG:
NewEC2Instance:
    Type: AWS::EC2::Instance
    DependsOn: OldSecurityGroup
    Properties:
      ImageId: !Ref pImageId
      InstanceType: !Ref pInstanceType
      BlockDeviceMappings:
        -
          DeviceName: /dev/sda1
          Ebs:
            VolumeSize: 10
          DeviceName: /dev/sdf
          Ebs:
            VolumeSize: 11
            Encrypted: true
          DeviceName: /dev/sdg
          Ebs:
            VolumeSize: 12
            Encrypted: true 
          DeviceName: /dev/sdh
          Ebs:
            VolumeSize: 100
            Encrypted: true 

For the above code, only the 100Gb /dev/sdh gets created.

I think Cloudformation is overwriting the EBS volumes.

Anyone know why? Please help!

Answer 1

You miss a - in front of each device name. Like so:

  BlockDeviceMappings:
  - DeviceName: "/dev/xvda"
    Ebs:
      VolumeSize: 16
      VolumeType: gp2
  - DeviceName: "/dev/xvdf"
    Ebs:
      VolumeSize: 12
      VolumeType: gp2

With only one - you were actually defining an array with a single element with conflicting keys, the default behavior for yaml is to use the last key it find in the object.