Bash snippet to poll attachment of EC2 volume

ec2_volume_check.sh

EC2_INSTANCE_ID=$(curl -s http://instance-data/latest/meta-data/instance-id)
DEVICE=/dev/sda

DATA_STATE="unknown"
until [ "$DATA_STATE" == "attached" ]; do
  DATA_STATE=$(aws ec2 describe-volumes \
    --region $REGION \
    --filters \
      Name=attachment.instance-id,Values=$EC2_INSTANCE_ID \
      Name=attachment.device,Values=$DEVICE \
    --query Volumes[].Attachments[].State \
    --output text)

  sleep 5
done