we're encountering a strange issue with AWS CloudFormation.
We're using CloudFormation in order to automate the deployment of some our machines; our CloudFormation yml describes the deployment, which contains a persistent EBS volume which was created outside the stack, and we don't want to remove or recreate along such stack (it contains a lot of the state of our application).
The relevant CloudFormation yml snippet is:
DataVolumeAttachment01:
Type: AWS::EC2::VolumeAttachment
Properties:
Device: "/dev/xvdm"
InstanceId: !Ref EC2Instance01
VolumeId: !Ref DataVolumeId
EC2Instance01:
Type: "AWS::EC2::Instance"
Properties:
ImageId: "ami-6f587e1c"
KeyName: !Ref "KeyName"
InstanceType: !Ref "InstanceType"
BlockDeviceMappings:
# Root device
- DeviceName: "/dev/sda1"
Ebs:
VolumeType: "gp2"
DeleteOnTermination: "true"
VolumeSize: 20
So, the root device is "transient" (every time the stack is updated, such volume is deleted and gets reprovisioned with userdata), while /dev/xvdm should contain our persistent data; such device gets mounted at the end of the userdata, and added to fstab.
Following AWS own documentation, I created a script that unmounts such volume from inside the VM, and I even tried deattaching such volume from the EC2 Instance, something like:
${SSH_CMD} "cd /home/application && application stop && sudo umount /data && echo data volume unmounted"
echo "detaching data volume"
VOLID=$(aws ec2 describe-volumes --filters Name=tag-key,Values="Name" Name=tag-value,Values=persistent-volume --query 'Volumes[*].{ID:VolumeId}' --output text)
aws ec2 detach-volume --volume-id "${VOLID}"
I have verified the umount and the detach succeed.
The creation of a new stack with my template and parameters succeeds.
And yet, when I launch
aws cloudformation update-stack --capabilities CAPABILITY_IAM --stack-name $STACK_NAME --template-body file://single_ec2_instance.yml --parameters file://$AWS_PARAMETERS_FILE
The update fails, with this error:
Update to resource type AWS::EC2::VolumeAttachment is not supported.
Even though I'm not changing anything within such resource.
What's up? How can I solve or work around?
