k3d

k3d is a CLI for running k3s Kubernetes clusters as Docker containers on one machine. It is mainly a fast local control surface for spinning clusters up and down, wiring access, and shaping repeatable dev or test environments.

• Create single-node or multi-node local k3s clusters, start or stop them, and delete them when a test or debugging run is done.
• Merge or write kubeconfig for those clusters, create or attach local registries, and import container images without pushing to a remote registry first.
• Define cluster shape in YAML config files, validate or migrate that config, and reuse the same setup across local development, CI, or agent-run test loops.

• Well suited to local inspect-change-verify loops because cluster lifecycle commands are explicit, non-TUI, and easy to script around Docker plus kubectl.
• Structured output exists, but only on part of the surface: version supports JSON and cluster, node, and registry list support -o json|yaml, while most create or mutate commands log human-oriented progress.
• Best when an agent needs disposable Kubernetes environments on a machine it already controls, not when it needs full cluster introspection without follow-up tools.

• Requires a working Docker runtime, and practical use usually also depends on kubectl plus whatever manifests or tooling you run inside the cluster.
• k3d is community-run rather than an official Rancher or SUSE CLI, and its config format is still documented as alpha and subject to change.