Kubernetes Policy Management

Manage policies using kubectl-mcp-server's Kyverno and Gatekeeper tools.

Requires the policy toolset: start kubectl-mcp-server with --toolsets default,policy (or MCP_TOOLSETS=default,policy). For deep work, the project-maintained MCP servers may fit better: Kyverno: https://github.com/nirmata/kyverno-mcp.

When to Apply

Use this skill when:

• User mentions: "Kyverno", "Gatekeeper", "OPA", "policy", "compliance"
• Operations: enforcing policies, checking violations, policy audit
• Keywords: "require labels", "block privileged", "validate", "enforce"

Priority Rules

Priority	Rule	Impact	Tools
1	Detect policy engine first	CRITICAL	detect_ecosystem, detect_ecosystem
2	Use Audit mode before Enforce	HIGH	validationFailureAction
3	Check policy reports for violations	HIGH	get_policy_violations
4	Review constraint templates	MEDIUM	get_policy_list

Quick Reference

Task	Tool	Example
List Kyverno cluster policies	get_policy_list	get_policy_list()
Get Kyverno policy	get_policy	get_policy(name)
List Gatekeeper constraints	get_policy_list	get_policy_list()
Get constraint	get_policy	get_policy(kind, name)

Kyverno

Detect Installation

detect_ecosystem()

List Policies

get_policy_list()

get_policy_list(namespace="default")

Get Policy Details

get_policy(name="require-labels")
get_policy(name="require-resources", namespace="default")

Policy Reports

get_policy_violations()

get_policy_violations(namespace="default")

Common Kyverno Policies

kubectl_apply(manifest="""
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: require-labels
spec:
  validationFailureAction: Enforce
  rules:
  - name: require-app-label
    match:
      resources:
        kinds:
        - Pod
    validate:
      message: "Label 'app' is required"
      pattern:
        metadata:
          labels:
            app: "?*"
""")

kubectl_apply(manifest="""
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: require-limits
spec:
  validationFailureAction: Enforce
  rules:
  - name: require-cpu-memory
    match:
      resources:
        kinds:
        - Pod
    validate:
      message: "CPU and memory limits required"
      pattern:
        spec:
          containers:
          - resources:
              limits:
                cpu: "?*"
                memory: "?*"
""")

Gatekeeper (OPA)

Detect Installation

detect_ecosystem()

List Constraints

get_policy_list()

get_policy_list()

Get Constraint Details

get_policy(
    kind="K8sRequiredLabels",
    name="require-app-label"
)

get_policy(name="k8srequiredlabels")

Common Gatekeeper Policies

kubectl_apply(manifest="""
apiVersion: templates.gatekeeper.sh/v1
kind: ConstraintTemplate
metadata:
  name: k8srequiredlabels
spec:
  crd:
    spec:
      names:
        kind: K8sRequiredLabels
      validation:
        openAPIV3Schema:
          type: object
          properties:
            labels:
              type: array
              items:
                type: string
  targets:
  - target: admission.k8s.gatekeeper.sh
    rego: |
      package k8srequiredlabels
      violation[{"msg": msg}] {
        provided := {label | input.review.object.metadata.labels[label]}
        required := {label | label := input.parameters.labels[_]}
        missing := required - provided
        count(missing) > 0
        msg := sprintf("Missing labels: %v", [missing])
      }
""")

kubectl_apply(manifest="""
apiVersion: constraints.gatekeeper.sh/v1beta1
kind: K8sRequiredLabels
metadata:
  name: require-app-label
spec:
  match:
    kinds:
    - apiGroups: [""]
      kinds: ["Pod"]
  parameters:
    labels: ["app", "env"]
""")

Policy Audit Workflow

detect_ecosystem()
get_policy_list()
get_policy_violations()

Prerequisites

• Kyverno: Required for Kyverno tools

  kubectl create -f https://github.com/kyverno/kyverno/releases/latest/download/install.yaml
  

• Gatekeeper: Required for Gatekeeper tools

  kubectl apply -f https://raw.githubusercontent.com/open-policy-agent/gatekeeper/master/deploy/gatekeeper.yaml
  

Related Skills

• k8s-security - RBAC and security
• k8s-operations - Apply policies