> What I want is a lightweight infrastructure for macro-services. I want something to handle the user and machine-to-machine authentication (and maybe authorization).

> I don't WANT the usual K8s virtual network for that, just an easy-to-use module inside the service itself.

K8s makes sense if you have a dedicated team (or atleast engineer) and if you really need need the advanced stuff (blue/green deployments, scaling, etc). Once it's properly setup it's actually a very pleasant platform.

If you don't need that Docker (or preferable Podman) is indeed the way to go. You can actually go quite far with a VPS or a dedicated server these day. By the time you outgrow the most expensive server you can (reasonable) buy you can probably afford the staff to roll out a "big boy" infrastructure.

Unless you need horizontal scalability or clustering, Compose + Terraform is all you need.

With Compose, you get proper n-tier application containerization with immutability. By adding an infrastructure-as-code tool such as Terraform to abstract your IT environment, you can deploy your application on-premises, in the cloud, or at a customer site with a single command.

For clustering needs, there’s Incus, and finally, Kubernetes for very fast scalability (<mn), massive deployments on large clusters, cloud offloading, and microservices.

Almost nobody truly needs the complexity of Kubernetes. The ROI simply isn’t there for the majority of use cases.