aws-cdk

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dformation runs the actual deployment. [0]: https://github.com/aws/aws-cdk

ct in Root.*contents } // Every fs object is in at most one directory assert oneLocation { all o: FSObject | lone d: Dir | o in d.contents } I initially thought these model checking languages were purely academic in nature. But then a curious problem came up when I was working at AWS where folks were complaining that IAM policies generated by our library were sometimes growing to be too large in size (usually the limit was a few KB) - often due to redundant statements. To solve this, a coworker implemented some code for merging IAM policies -- though the merging processe wasn't trivial because IAM policies can have both "Resources" and "NotResources", "Actions" and "NotActions", "Principals" and "NotPrincipals" etc. So to prove the algorithm was correct, he wrote up a short Alloy specification[1] (roughly mapping to the library code) that proved if two policy statements were merged, it wouldn't change the security posture. As a new engineer to the team, I'll just say that it blew my mind that this was possible -- actually using proofs to achieve goals in industry. Needless to say, I'm curious to dive into Quint's differences and what kinds of models/specifications it excels with. [1] https://github.com/aws/aws-cdk/blob/main/packages/aws-cdk-li...

daches. CloudFormation can't handle serial operations that require "create & permute" sequences -- where two things have to be set up in order, then glued together later after some kind of configuration. The way the CDK does this is by deploying lambdas that get invoked after your stack is shipped out that make the relevant API calls. Terraform does this by having the code that Terraform runs make the API call. The difference here gets to be that the CDK can synthesize a change long before it is actually effected, allowing for things like second order permutations. Terraform does everything in-situ, standing up infrastructure and taking the place of both the CDK and CloudFormation. This has upsides and downsides on both, but a large upside (IMO, again) of the CDK approach is that you can code-wise validate certain things ahead of time before they're deployed, whereas with Terraform it's a little harder. Terraform's big upside is that it handles things that are Hard to do with CloudFormation alone by letting you figure out how to actually create/destroy that bit of infrastructure and hook up the relevant parts as one action in one codebase, rather than having to write Lambda handlers (the CDK calls these handlers "Custom Resource", which are different from Constructs) that get deployed and called when you need to setup/teardown/change the relevant parts. Both Terraform and the CDK are opaque wrappers around AWS as a whole, the difference being that Terraform wrote their own DSL to describe things that gets then attached to their own SDK (which appears to be JS?) with varying levels of integration, whereas the CDK allows you to use whatever language you're already using to build the primary structure of your application, but where you have fully atomic (not just rollback-able) changes via CloudFormation. [0]github.com/aws/aws-cdk/issues/new