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Zhongwei Li
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skills/k8s-security-policies/SKILL.md
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skills/k8s-security-policies/SKILL.md
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---
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name: k8s-security-policies
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description: Implement Kubernetes security policies including NetworkPolicy, PodSecurityPolicy, and RBAC for production-grade security. Use when securing Kubernetes clusters, implementing network isolation, or enforcing pod security standards.
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---
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# Kubernetes Security Policies
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Comprehensive guide for implementing NetworkPolicy, PodSecurityPolicy, RBAC, and Pod Security Standards in Kubernetes.
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## Purpose
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Implement defense-in-depth security for Kubernetes clusters using network policies, pod security standards, and RBAC.
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## When to Use This Skill
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- Implement network segmentation
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- Configure pod security standards
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- Set up RBAC for least-privilege access
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- Create security policies for compliance
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- Implement admission control
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- Secure multi-tenant clusters
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## Pod Security Standards
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### 1. Privileged (Unrestricted)
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```yaml
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apiVersion: v1
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kind: Namespace
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metadata:
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name: privileged-ns
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labels:
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pod-security.kubernetes.io/enforce: privileged
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pod-security.kubernetes.io/audit: privileged
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pod-security.kubernetes.io/warn: privileged
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```
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### 2. Baseline (Minimally restrictive)
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```yaml
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apiVersion: v1
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kind: Namespace
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metadata:
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name: baseline-ns
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labels:
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pod-security.kubernetes.io/enforce: baseline
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pod-security.kubernetes.io/audit: baseline
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pod-security.kubernetes.io/warn: baseline
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```
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### 3. Restricted (Most restrictive)
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```yaml
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apiVersion: v1
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kind: Namespace
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metadata:
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name: restricted-ns
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labels:
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pod-security.kubernetes.io/enforce: restricted
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pod-security.kubernetes.io/audit: restricted
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pod-security.kubernetes.io/warn: restricted
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```
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## Network Policies
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### Default Deny All
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```yaml
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apiVersion: networking.k8s.io/v1
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kind: NetworkPolicy
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metadata:
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name: default-deny-all
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namespace: production
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spec:
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podSelector: {}
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policyTypes:
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- Ingress
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- Egress
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```
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### Allow Frontend to Backend
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```yaml
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apiVersion: networking.k8s.io/v1
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kind: NetworkPolicy
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metadata:
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name: allow-frontend-to-backend
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namespace: production
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spec:
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podSelector:
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matchLabels:
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app: backend
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policyTypes:
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- Ingress
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ingress:
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- from:
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- podSelector:
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matchLabels:
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app: frontend
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ports:
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- protocol: TCP
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port: 8080
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```
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### Allow DNS
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```yaml
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apiVersion: networking.k8s.io/v1
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kind: NetworkPolicy
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metadata:
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name: allow-dns
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namespace: production
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spec:
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podSelector: {}
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policyTypes:
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- Egress
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egress:
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- to:
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- namespaceSelector:
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matchLabels:
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name: kube-system
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ports:
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- protocol: UDP
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port: 53
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```
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**Reference:** See `assets/network-policy-template.yaml`
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## RBAC Configuration
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### Role (Namespace-scoped)
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```yaml
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apiVersion: rbac.authorization.k8s.io/v1
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kind: Role
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metadata:
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name: pod-reader
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namespace: production
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rules:
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- apiGroups: [""]
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resources: ["pods"]
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verbs: ["get", "watch", "list"]
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```
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### ClusterRole (Cluster-wide)
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```yaml
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apiVersion: rbac.authorization.k8s.io/v1
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kind: ClusterRole
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metadata:
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name: secret-reader
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rules:
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- apiGroups: [""]
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resources: ["secrets"]
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verbs: ["get", "watch", "list"]
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```
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### RoleBinding
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```yaml
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apiVersion: rbac.authorization.k8s.io/v1
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kind: RoleBinding
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metadata:
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name: read-pods
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namespace: production
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subjects:
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- kind: User
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name: jane
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apiGroup: rbac.authorization.k8s.io
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- kind: ServiceAccount
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name: default
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namespace: production
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roleRef:
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kind: Role
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name: pod-reader
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apiGroup: rbac.authorization.k8s.io
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```
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**Reference:** See `references/rbac-patterns.md`
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## Pod Security Context
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### Restricted Pod
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```yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: secure-pod
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spec:
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securityContext:
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runAsNonRoot: true
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runAsUser: 1000
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fsGroup: 1000
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seccompProfile:
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type: RuntimeDefault
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containers:
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- name: app
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image: myapp:1.0
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securityContext:
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allowPrivilegeEscalation: false
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readOnlyRootFilesystem: true
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capabilities:
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drop:
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- ALL
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```
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## Policy Enforcement with OPA Gatekeeper
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### ConstraintTemplate
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```yaml
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apiVersion: templates.gatekeeper.sh/v1
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kind: ConstraintTemplate
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metadata:
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name: k8srequiredlabels
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spec:
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crd:
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spec:
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names:
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kind: K8sRequiredLabels
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validation:
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openAPIV3Schema:
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type: object
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properties:
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labels:
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type: array
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items:
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type: string
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targets:
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- target: admission.k8s.gatekeeper.sh
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rego: |
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package k8srequiredlabels
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violation[{"msg": msg, "details": {"missing_labels": missing}}] {
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provided := {label | input.review.object.metadata.labels[label]}
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required := {label | label := input.parameters.labels[_]}
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missing := required - provided
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count(missing) > 0
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msg := sprintf("missing required labels: %v", [missing])
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}
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```
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### Constraint
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```yaml
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apiVersion: constraints.gatekeeper.sh/v1beta1
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kind: K8sRequiredLabels
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metadata:
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name: require-app-label
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spec:
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match:
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kinds:
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- apiGroups: ["apps"]
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kinds: ["Deployment"]
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parameters:
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labels: ["app", "environment"]
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```
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## Service Mesh Security (Istio)
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### PeerAuthentication (mTLS)
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```yaml
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apiVersion: security.istio.io/v1beta1
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kind: PeerAuthentication
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metadata:
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name: default
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namespace: production
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spec:
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mtls:
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mode: STRICT
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```
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### AuthorizationPolicy
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```yaml
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apiVersion: security.istio.io/v1beta1
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kind: AuthorizationPolicy
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metadata:
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name: allow-frontend
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namespace: production
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spec:
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selector:
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matchLabels:
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app: backend
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action: ALLOW
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rules:
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- from:
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- source:
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principals: ["cluster.local/ns/production/sa/frontend"]
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```
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## Best Practices
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1. **Implement Pod Security Standards** at namespace level
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2. **Use Network Policies** for network segmentation
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3. **Apply least-privilege RBAC** for all service accounts
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4. **Enable admission control** (OPA Gatekeeper/Kyverno)
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5. **Run containers as non-root**
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6. **Use read-only root filesystem**
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7. **Drop all capabilities** unless needed
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8. **Implement resource quotas** and limit ranges
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9. **Enable audit logging** for security events
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10. **Regular security scanning** of images
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## Compliance Frameworks
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### CIS Kubernetes Benchmark
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- Use RBAC authorization
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- Enable audit logging
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- Use Pod Security Standards
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- Configure network policies
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- Implement secrets encryption at rest
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- Enable node authentication
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### NIST Cybersecurity Framework
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- Implement defense in depth
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- Use network segmentation
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- Configure security monitoring
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- Implement access controls
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- Enable logging and monitoring
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## Troubleshooting
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**NetworkPolicy not working:**
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```bash
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# Check if CNI supports NetworkPolicy
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kubectl get nodes -o wide
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kubectl describe networkpolicy <name>
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```
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**RBAC permission denied:**
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```bash
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# Check effective permissions
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kubectl auth can-i list pods --as system:serviceaccount:default:my-sa
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kubectl auth can-i '*' '*' --as system:serviceaccount:default:my-sa
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```
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## Reference Files
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- `assets/network-policy-template.yaml` - Network policy examples
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- `assets/pod-security-template.yaml` - Pod security policies
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- `references/rbac-patterns.md` - RBAC configuration patterns
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## Related Skills
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- `k8s-manifest-generator` - For creating secure manifests
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- `gitops-workflow` - For automated policy deployment
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