{
  "id": "cks-runtime-class",
  "title": "RuntimeClass for Sandboxed Workloads",
  "category": "System Hardening",
  "difficulty": "Medium",
  "type": "task",
  "weight": 5,
  "description": "## RuntimeClass for Stronger Workload Isolation\n\nKubernetes `RuntimeClass` lets you select an alternative container runtime (such as gVisor's `runsc`) for specific pods, providing stronger kernel-level isolation than the default `runc`.\n\n**Your task:**\n\n1. Create a `RuntimeClass` named `gvisor` with `handler: runsc`.\n2. Create a Pod named `sandbox-pod` using the `nginx:alpine` image that references this RuntimeClass via `spec.runtimeClassName: gvisor`.\n\n```bash\n# Verify the RuntimeClass:\nkubectl get runtimeclass gvisor\n# Verify the pod spec:\nkubectl get pod sandbox-pod -o jsonpath='{.spec.runtimeClassName}'\n```\n\n> **Note:** The pod may not reach `Running` state if `runsc` is not installed on the node — that is expected in this lab. Validation only checks the API object configuration.",
  "hints": [
    {
      "title": "Create the RuntimeClass",
      "body": "Use a manifest with `apiVersion: node.k8s.io/v1`, `kind: RuntimeClass`, and a `handler` field.",
      "command": "cat <<EOF | kubectl apply -f -\napiVersion: node.k8s.io/v1\nkind: RuntimeClass\nmetadata:\n  name: gvisor\nhandler: runsc\nEOF"
    },
    {
      "title": "Reference the RuntimeClass in a Pod",
      "body": "Set `spec.runtimeClassName: gvisor` in the pod spec.",
      "command": "cat <<EOF | kubectl apply -f -\napiVersion: v1\nkind: Pod\nmetadata:\n  name: sandbox-pod\nspec:\n  runtimeClassName: gvisor\n  containers:\n  - name: app\n    image: nginx:alpine\nEOF"
    }
  ],
  "setup_commands": [],
  "validation": {
    "commands": [
      {
        "description": "RuntimeClass 'gvisor' exists with handler runsc",
        "command": "kubectl get runtimeclass gvisor -o jsonpath='{.handler}'",
        "expected_output": "runsc",
        "match": "exact"
      },
      {
        "description": "Pod 'sandbox-pod' references RuntimeClass gvisor",
        "command": "kubectl get pod sandbox-pod -o jsonpath='{.spec.runtimeClassName}'",
        "expected_output": "gvisor",
        "match": "exact"
      }
    ]
  },
  "default_namespace": "default",
  "teardown_commands": [
    {
      "command": "kubectl delete pod sandbox-pod --ignore-not-found --grace-period=0 --force"
    },
    {
      "command": "kubectl delete runtimeclass gvisor --ignore-not-found"
    }
  ]
}
