I went to a serverless conference some time ago (great excuse to travel on the company's dime), and every single talk had a few minutes about how they were unable to test or debug their production infrastructure.
They couldn't even run their code locally, just bits of it. Serverless code could not run without a server. A specific provider's servers.
Call me old-fashioned, but I develop with a few docker containers locally, then release them to a plain old linux server, and it's working great. Sure, my humble business isn't Google, but neither are yours, right?
I went to one too, and saw a talk about synchronising data between microservices and was astounded at how much work it was and the fact they had a whole team just to build tooling to debug issues on this specific company.
Basically they store 100x more data than they need because of data duplication between microservices. The company didn't even have that much customers (<1000), data or even enough users (a handful per company), but duplication was still generating several terabytes.
It's amazing how much complexity people are able to cram into simple system.
Agree that being unable to test serverless code locally is begging for pain. While not perfect, testing AWS Lambda has improved over the years. I recently deployed a Lambda function only because I was able to reproduce the environment locally, using their Lambda Runtime Interface Emulator (RIE):
Until you need to connect to another service that can not be run locally and it is only accesible within the same Cloud Provider.
Sure it's not impossible to go around that, start mocking or run some alternative locally for debugging but I don't think this extra level of complexity is necessary (at least not always).
They couldn't even run their code locally, just bits of it. Serverless code could not run without a server. A specific provider's servers.
Call me old-fashioned, but I develop with a few docker containers locally, then release them to a plain old linux server, and it's working great. Sure, my humble business isn't Google, but neither are yours, right?