~$ aws ec2 describe-instances \
   --output text --query 'Reservations[*].Instances[*].InstanceType'
t2.micro
 
~$ sed -i 's/t2.micro/t2.small/' nginx-simple.json
 
~$ aws cloudformation update-stack --stack-name mystack \
   --template-body file://nginx-simple.json
 
~$ aws cloudformation describe-stacks --stack-name mystack \
   --output text --query 'Stacks[*].StackStatus'
UPDATE_COMPLETE
 
~$ aws ec2 describe-instances \
   --output text --query 'Reservations[*].Instances[*].InstanceType'
t2.small
