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Comment by dack | Hacker News Reader

Not the parent, but for one, doing a CF update is all-or-nothing. Either you roll the whole thing out, or you roll the whole thing back. If you have a lot of servers, and things are going down, you want to just STOP. But you can't. Also, if you click too quickly, sometimes you can get into a weird state and not be able to rollback OR update anymore.

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I think this behavior is sensible. Additionally, you can disable rollback. However, cloud formation has needed and lacked a "dry run" option for a long time. It would be really nice to have that. However, the documentation does indicate what effect an update on any given resource will have.

I recommend against making sweeping changes to your infrastructure without thoroughness. Without saying this is what you're doing, I see a lot of developers who get involved with cloud treating changes whimsically. I'm not saying you should write perfect code. But thoroughness and a solid procedure (and backup plan) is a good place to start.

dry run for cfn == create change set :-)

(also, it helps to use nested stacks)

Same thing happens with other tools like Terraform though: once you've kicked off an apply, you are committed.

yeah, but having the option to run 'terraform plan' really helps you know what you're getting yourself into.

We've had Terraform take action that wasn't in the plan, in production.

I call it "pray and apply".

https://news.ycombinator.com/item?id=12214879

BOSH is able to cancel operations. You press Ctrl+C and it asks if that's what you intend.

CloudFormation change sets make CF updates a little less painful/mysterious:

https://aws.amazon.com/blogs/aws/new-change-sets-for-aws-clo...

changeset is very limited. when you have sub stack, change set cannot detect thing change in sub stack :(

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