If your complaint about Kubernetes is that it doesn’t provide you enough choice/extensibility, you’re probably not looking hard enough. Runtimes (CRI) - Docker

If your complaint about Kubernetes is that it doesn’t provide you enough choice/extensibility, you’re probably not looking hard enough. Runtimes (CRI) - Docker shim (deprecated), containerd, CRI-O, kata Networking (CNI) - Flannel, Calico, Cilium, cloud specific ones, many more Storage (CSI) - way too many device plugins - GPU, TPU, RDMA/SRIOV NICs Data store - etcd, dqlite in microk8s, SQLite/postgresql/mysql in k3s DNS - kube-dns (somewhat deprecated), CoreDNS Ingress - NGINX (multiple), HAProxy, Envoy (many), etc Kubelet -https://github.com/virtual-kubelet/virtual-kubelet https://github.com/virtual-kubelet/virtual-kubelet Kube-proxy - Cilium can act as a replacement Cloud-controller-manager for each cloud provider kube-scheduler - https://kubernetes.io/docs/tasks/extend-kubernetes/configure-multiple-schedulers/ https://kubernetes.io/docs/tasks/extend-kubernetes/configure... kube-apiserver and kube-controller-manager are two parts where I’m not aware of any other implementations but a) they are kind of the heart of k8s and b) can be easily extended with CRDs/operators.