Cluster API vs Clusternet

Cluster API is an open-source project for managing the lifecycle of multiple Kubernetes clusters through declarative APIs and tooling. Platform operators can use it to create, scale, upgrade, and destroy Kubernetes-conformant clusters across on-premises and cloud environments. Provider implementations are interchangeable; kubeadm is the default bootstrap provider. The ecosystem includes infrastructure, bootstrap, control plane, IPAM, addon, and runtime extensions, with environments such as AWS, Azure, GCP, OpenStack, vSphere, and KubeVirt. A management cluster can use clusterctl or the Cluster API Operator to manage provider components. Clusterctl fetches provider component YAML and installs it, while the Operator uses a declarative approach intended to support GitOps workflows. Getting started requires an existing Kubernetes cluster accessible through kubectl; kind, Docker, and Helm are common prerequisites. Cluster API supports multi-cluster provisioning and upgrades, but does not manage a single cluster spanning multiple infrastructure providers or clusters it did not provision. It is free and open source. The project supports its latest two minor releases, with each supported for roughly 12 months including maintenance.

Clusternet is a free, open-source add-on for managing Kubernetes clusters across public and private cloud, hybrid, on-premises, and edge environments. It lets operators manage member clusters from a parent cluster and access them as though they were local. It deploys Kubernetes resources, custom resource definitions, and Helm charts, with configuration tailored to individual clusters. Application scheduling can replicate workloads or distribute them by cluster weight or available capacity. Clusternet supports clusters from AWS, Google Cloud, Tencent Cloud, and Alibaba Cloud, along with on-premises systems, k3s, and edge clusters. It can discover and register clusters created by Cluster API and configure network tunnels for clusters in VPC networks, at the edge, or behind a firewall. Dynamic RBAC rules control access to managed clusters, and Submariner integration can connect workloads across clusters. Installation options include Helm and manual setup. A kubectl plugin is available through Krew or as a binary. Linux builds are listed for several architectures. Clusternet is a CNCF Sandbox project.