I see this often mentioned in the context of k8s and find it baffling that it gets repeated. K8s is simply swapping a form of lock in, to the abstract layer.
K8s does have a lot of open interfaces like CRI, CNI, CSI that can & are used in other solutions like Hashicorp Nomad.
The core/control plane components aren't interchangeable but a lot of the "userland" can be swapped around (I have cri-o, Calico, and a homemade CSI on libvirt VMs at home and it runs workloads the same as containerd, AWS VPC CNI, EBS CSI at work)
However, it's not open in the way there's a drop in replacement
The core/control plane components aren't interchangeable but a lot of the "userland" can be swapped around (I have cri-o, Calico, and a homemade CSI on libvirt VMs at home and it runs workloads the same as containerd, AWS VPC CNI, EBS CSI at work)
However, it's not open in the way there's a drop in replacement