rancher/k3k

K3k is a tool for running Kubernetes clusters within an existing Kubernetes environment.

K3k addresses the challenge of running multiple isolated Kubernetes clusters on shared infrastructure without the overhead of managing separate physical machines. It works by deploying lightweight K3s clusters as workloads inside a parent Kubernetes cluster, with two operational modes: shared mode optimizes resource utilization by allowing clusters to share underlying resources, while virtual mode provides stronger isolation by giving each embedded cluster dedicated control plane and node pods. This approach enables efficient multi-tenancy, supports experimentation and testing workflows, and reduces infrastructure costs by consolidating multiple clusters onto the same physical host.

Organizations should consider K3k when they need to provide isolated Kubernetes environments to multiple teams or projects without managing separate physical infrastructure, or when they want to streamline development and testing by quickly spinning up and tearing down temporary clusters. The tool suits scenarios requiring resource isolation with defined quotas and limits, simplified access control through separate RBAC configurations, and rapid cluster provisioning. K3k integrates with Rancher for centralized management of embedded clusters. Teams prioritizing maximum resource efficiency should use shared mode, while those needing stronger workload isolation should use virtual mode, though virtual mode currently requires privileged agent pods on the host node unless a sandboxed runtime like Kata Containers is configured.

The project maintains active test coverage including conformance tests for both virtual and shared modes. Development activity shows consistent attention to build and release processes with automated workflows for testing and releases.