[kelnos]

I don't think client libraries are the answer. If you only have one technology stack (say, Java and Spring) and only use one application-layer network protocol (say, HTTP), then maybe it's fine.

But once you have more than one language or framework, you need to write more and more of these libraries. And what happens if it's not just HTTP? What if you need to speak Redis, MySQL, or some random binary protocol? Do you write client libraries for those too? Maybe a company like Google has the scale to do this, but most orgs do not. But even then, what if you have to run some vendor-supplied code that you don't even have source for?

I agree with you that shoving more of this into the kernel isn't desirable, but libraries aren't great. Been there, done that, don't feel like doing it again. I'd rather stick with sidecars.