Agreed, having to dig through the AWS documentation to see what whether updating a particular value requires replacing the resource it applies to is tedious and

Agreed, having to dig through the AWS documentation to see what whether updating a particular value requires replacing the resource it applies to is tedious and error prone. Another things that excites me about separating the plan from the execution is that I can periodically run `terraform plan` to check for configuration drift without risking making a change. I've been bitten by the following: 1) Someone creates an ASG with the desired number of instances set to 1 via CloudFormation 2) Later, they increase the desired number of instances, e.g. to 5, via the EC2 console or API rather than CloudFormation 3) I come along and apply an update to the stack via CloudFormation. This resets their ASG to 1 instance, terminating the other 4. If anyone from AWS is reading this, please steal this feature for CloudFormation!