~$ aws cloudformation create-stack --stack-name mystack \
   --template-body file://nginx-param.json \
   --parameter ParameterKey=SSHSchluessel,ParameterValue=myawskey \
               ParameterKey=Instanzentyp,ParameterValue=t2.large
An error occurred (ValidationError) when calling the CreateStack operation:  
Parameter 'Instanzentyp' must be one of AllowedValues
