[ovao]

To add a couple more good use cases for Lambda:

- To run something at deploy-time with custom CloudFormation resources. As an example, a Lambda can be invoked during each deployment to run tests. If the test fails, the stack(s) can be automatically rolled back. Tricky to get right and not often the right tool in the bag, but sometimes useful.

- As handlers for CloudWatch events. Useful for forwarding events to third-party log services, or for taking some sort of complex action based on a given event.

AWS is nearly “all in” on Lambda at this point, so it’s a good bet that if you want to hang some kind of task off an AWS service, they’ll give you a hook to fire off a Lambda. From a cost and simplicity perspective this works out well.