Backend - Lambda / TypeScript
Infrastructure - AWS CDK / TypeScript
Kept in a monorepo, which means tightly-coupled code-sharing between all the different components.
Definitely has it's negatives - but being in small startup (solo technical) also means lots of interruptions and chopping and changing.
Having one language, stack, and repo makes it much easier to me to start, stop, and pick things up as I go.
It's funny how one persons dream is another person's nightmare.
Tightly coupled software is horrifying to me. Modularization all the way; define contracts then build away.
In this case, the contract is shared TypeScript types between the front and back-ends. This means you can statically verify as much as the type system allows.
Did you have a solid AWS experience prior?
A lot of cloudformation quirks leak directly into CDK. And I've learned to be patient (e.g. one change at a time, roll though all environments, do adds and deletes separately...).
Right now using it is 50/50 for me. I'm assuming as more construct libraries become commonplace that will help the most (up until recently this was hamstrung by the amount of breaking changes)