feat(kyverno): add policy engine with security baseline

- Kyverno 3.3.4 via Helm (HA config: 3 admission, 2 background replicas)
- Validation policies:
  - disallow-privileged-containers (Enforce)
  - require-resource-limits (Enforce)
  - require-labels (Audit - standard k8s labels)
  - require-run-as-non-root (Audit)
  - disallow-latest-tag (Enforce - GitOps reproducibility)
- Mutating policy:
  - add-default-securitycontext (seccomp, drop caps, read-only fs)
- System namespaces excluded (kube-system, kyverno, istio-system)
- Auto-discovered by ArgoCD ApplicationSet

Reference: CIS Kubernetes Benchmark, Pod Security Standards

infrastructure/kyverno/kustomization.yaml

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+# infrastructure/kyverno/kustomization.yaml
+# Kyverno Policy Engine - GitOps-native Kubernetes policy enforcement
+# CNCF Graduated project, integrates seamlessly with ArgoCD
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+namespace: kyverno
+
+resources:
+  - namespace.yaml
+  - policies/
+
+# Kyverno deployment via Helm
+helmCharts:
+  - name: kyverno
+    repo: https://kyverno.github.io/kyverno/
+    version: "3.3.4"
+    releaseName: kyverno
+    namespace: kyverno
+    valuesInline:
+      # Admission controller replicas for HA
+      admissionController:
+        replicas: 3
+        resources:
+          limits:
+            memory: 512Mi
+          requests:
+            cpu: 100m
+            memory: 256Mi
+      # Background controller for generate/mutate policies
+      backgroundController:
+        replicas: 2
+        resources:
+          limits:
+            memory: 256Mi
+          requests:
+            cpu: 50m
+            memory: 128Mi
+      # Reports controller for policy reports
+      reportsController:
+        replicas: 2
+      # Cleanup controller
+      cleanupController:
+        replicas: 2
+      # Enable policy exception support
+      features:
+        policyExceptions:
+          enabled: true
+          namespace: "kyverno"
+      # Webhooks config
+      config:
+        webhooks:
+          # Exclude system namespaces from validation
+          - namespaceSelector:
+              matchExpressions:
+                - key: kubernetes.io/metadata.name
+                  operator: NotIn
+                  values:
+                    - kube-system
+                    - kube-public
+                    - kube-node-lease
+                    - kyverno

infrastructure/kyverno/namespace.yaml

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+# infrastructure/kyverno/namespace.yaml
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: kyverno
+  labels:
+    app.kubernetes.io/name: kyverno
+    app.kubernetes.io/component: policy-engine
+    # Exempt from Pod Security Standards (Kyverno needs privileges)
+    pod-security.kubernetes.io/enforce: privileged

infrastructure/kyverno/policies/add-default-securitycontext.yaml

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+# infrastructure/kyverno/policies/add-default-securitycontext.yaml
+# Mutating policy: adds secure defaults to pods missing securityContext
+# Implements defense-in-depth by setting secure defaults
+apiVersion: kyverno.io/v1
+kind: ClusterPolicy
+metadata:
+  name: add-default-securitycontext
+  annotations:
+    policies.kyverno.io/title: Add Default Security Context
+    policies.kyverno.io/category: Best Practices
+    policies.kyverno.io/severity: low
+    policies.kyverno.io/subject: Pod
+    policies.kyverno.io/description: >-
+      Mutating policy that adds secure default securityContext to pods
+      that don't specify one. Reduces attack surface by dropping
+      capabilities and making filesystem read-only where possible.
+    pod-policies.kyverno.io/autogen-controllers: DaemonSet,Deployment,Job,StatefulSet,ReplicaSet
+spec:
+  # Mutate rules apply during admission
+  rules:
+    - name: add-pod-security-context
+      match:
+        any:
+          - resources:
+              kinds:
+                - Pod
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+                - istio-system
+      mutate:
+        patchStrategicMerge:
+          spec:
+            # Add pod-level securityContext if missing
+            +(securityContext):
+              seccompProfile:
+                type: RuntimeDefault
+              # Don't allow privilege escalation by default
+              runAsNonRoot: true
+    - name: add-container-security-context
+      match:
+        any:
+          - resources:
+              kinds:
+                - Pod
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+                - istio-system
+      mutate:
+        foreach:
+          - list: "request.object.spec.containers"
+            patchStrategicMerge:
+              spec:
+                containers:
+                  - name: "{{ element.name }}"
+                    +(securityContext):
+                      allowPrivilegeEscalation: false
+                      capabilities:
+                        drop:
+                          - ALL
+                      readOnlyRootFilesystem: true

infrastructure/kyverno/policies/disallow-latest-tag.yaml

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+# infrastructure/kyverno/policies/disallow-latest-tag.yaml
+# Prevents use of 'latest' image tag for reproducibility
+# GitOps best practice: always use explicit image versions
+apiVersion: kyverno.io/v1
+kind: ClusterPolicy
+metadata:
+  name: disallow-latest-tag
+  annotations:
+    policies.kyverno.io/title: Disallow Latest Tag
+    policies.kyverno.io/category: Best Practices
+    policies.kyverno.io/severity: medium
+    policies.kyverno.io/subject: Pod
+    policies.kyverno.io/description: >-
+      The 'latest' tag is mutable and can change unexpectedly, making
+      deployments non-reproducible. This policy requires explicit
+      image tags for GitOps traceability.
+spec:
+  validationFailureAction: Enforce
+  background: true
+  rules:
+    - name: require-image-tag
+      match:
+        any:
+          - resources:
+              kinds:
+                - Pod
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+      validate:
+        message: "Images must use an explicit tag (not 'latest'). Specify a version tag like ':v1.2.3' or SHA digest."
+        pattern:
+          spec:
+            containers:
+              - image: "*:*"
+            =(initContainers):
+              - image: "*:*"
+    - name: validate-not-latest
+      match:
+        any:
+          - resources:
+              kinds:
+                - Pod
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+      validate:
+        message: "The 'latest' tag is not allowed. Use a specific version tag."
+        pattern:
+          spec:
+            containers:
+              - image: "!*:latest"
+            =(initContainers):
+              - image: "!*:latest"

infrastructure/kyverno/policies/disallow-privileged.yaml

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+# infrastructure/kyverno/policies/disallow-privileged.yaml
+# Prevents pods from running as privileged containers
+# Security baseline: CIS Benchmark 5.2.1
+apiVersion: kyverno.io/v1
+kind: ClusterPolicy
+metadata:
+  name: disallow-privileged-containers
+  annotations:
+    policies.kyverno.io/title: Disallow Privileged Containers
+    policies.kyverno.io/category: Pod Security Standards (Baseline)
+    policies.kyverno.io/severity: high
+    policies.kyverno.io/subject: Pod
+    policies.kyverno.io/description: >-
+      Privileged containers have all Linux capabilities and can access
+      host resources. This policy prevents privileged containers from
+      being created except in system namespaces.
+spec:
+  validationFailureAction: Enforce
+  background: true
+  rules:
+    - name: privileged-containers
+      match:
+        any:
+          - resources:
+              kinds:
+                - Pod
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+                - istio-system
+                - cert-manager
+      validate:
+        message: "Privileged containers are not allowed. Set securityContext.privileged to false."
+        pattern:
+          spec:
+            containers:
+              - securityContext:
+                  privileged: "false"
+            =(initContainers):
+              - securityContext:
+                  privileged: "false"
+            =(ephemeralContainers):
+              - securityContext:
+                  privileged: "false"

infrastructure/kyverno/policies/kustomization.yaml

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+# infrastructure/kyverno/policies/kustomization.yaml
+# Security policies for cluster-wide enforcement
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - disallow-privileged.yaml
+  - require-resource-limits.yaml
+  - require-labels.yaml
+  - require-non-root.yaml
+  - disallow-latest-tag.yaml
+  - add-default-securitycontext.yaml

infrastructure/kyverno/policies/require-labels.yaml

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+# infrastructure/kyverno/policies/require-labels.yaml
+# Enforces standard labeling for all workloads
+# Enables proper resource organization and cost tracking
+apiVersion: kyverno.io/v1
+kind: ClusterPolicy
+metadata:
+  name: require-labels
+  annotations:
+    policies.kyverno.io/title: Require Labels
+    policies.kyverno.io/category: Best Practices
+    policies.kyverno.io/severity: medium
+    policies.kyverno.io/subject: Pod, Deployment, StatefulSet, DaemonSet
+    policies.kyverno.io/description: >-
+      Labels are essential for organizing, filtering, and managing
+      Kubernetes resources. This policy requires standard labels on
+      all workloads.
+spec:
+  validationFailureAction: Audit  # Start in audit mode
+  background: true
+  rules:
+    - name: check-deployment-labels
+      match:
+        any:
+          - resources:
+              kinds:
+                - Deployment
+                - StatefulSet
+                - DaemonSet
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+      validate:
+        message: "Workloads must have 'app.kubernetes.io/name' and 'app.kubernetes.io/part-of' labels."
+        pattern:
+          metadata:
+            labels:
+              app.kubernetes.io/name: "?*"
+              app.kubernetes.io/part-of: "?*"
+    - name: check-pod-labels
+      match:
+        any:
+          - resources:
+              kinds:
+                - Pod
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+              # Exclude pods created by controllers (they inherit parent labels)
+              selector:
+                matchLabels:
+                  app.kubernetes.io/managed-by: "*"
+      preconditions:
+        all:
+          # Only check standalone pods (not owned by ReplicaSet, etc.)
+          - key: "{{ request.object.metadata.ownerReferences[] || `[]` | length(@) }}"
+            operator: Equals
+            value: 0
+      validate:
+        message: "Pods must have 'app.kubernetes.io/name' label."
+        pattern:
+          metadata:
+            labels:
+              app.kubernetes.io/name: "?*"

infrastructure/kyverno/policies/require-non-root.yaml

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+# infrastructure/kyverno/policies/require-non-root.yaml
+# Requires containers to run as non-root user
+# Security baseline: CIS Benchmark 5.2.6
+apiVersion: kyverno.io/v1
+kind: ClusterPolicy
+metadata:
+  name: require-run-as-non-root
+  annotations:
+    policies.kyverno.io/title: Require Run As Non-Root
+    policies.kyverno.io/category: Pod Security Standards (Restricted)
+    policies.kyverno.io/severity: high
+    policies.kyverno.io/subject: Pod
+    policies.kyverno.io/description: >-
+      Running as root inside a container is a security risk. If a
+      container breakout occurs, root in the container could become
+      root on the host. This policy requires containers to run as
+      a non-root user.
+spec:
+  validationFailureAction: Audit  # Audit first, Enforce after baseline
+  background: true
+  rules:
+    - name: run-as-non-root
+      match:
+        any:
+          - resources:
+              kinds:
+                - Pod
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+                - istio-system
+      validate:
+        message: "Containers must run as non-root. Set runAsNonRoot: true or specify a non-root runAsUser."
+        anyPattern:
+          # Pattern 1: Pod-level runAsNonRoot
+          - spec:
+              securityContext:
+                runAsNonRoot: true
+          # Pattern 2: Container-level runAsNonRoot
+          - spec:
+              containers:
+                - securityContext:
+                    runAsNonRoot: true
+          # Pattern 3: Explicit non-root UID (>= 1000)
+          - spec:
+              securityContext:
+                runAsUser: ">999"
+          - spec:
+              containers:
+                - securityContext:
+                    runAsUser: ">999"

infrastructure/kyverno/policies/require-resource-limits.yaml

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+# infrastructure/kyverno/policies/require-resource-limits.yaml
+# Ensures all pods have resource limits defined
+# Prevents resource exhaustion and enables proper scheduling
+apiVersion: kyverno.io/v1
+kind: ClusterPolicy
+metadata:
+  name: require-resource-limits
+  annotations:
+    policies.kyverno.io/title: Require Resource Limits
+    policies.kyverno.io/category: Best Practices
+    policies.kyverno.io/severity: medium
+    policies.kyverno.io/subject: Pod
+    policies.kyverno.io/description: >-
+      Resource limits prevent a single workload from consuming excessive
+      cluster resources. This policy requires all containers to define
+      CPU and memory limits.
+spec:
+  validationFailureAction: Enforce
+  background: true
+  rules:
+    - name: validate-resources
+      match:
+        any:
+          - resources:
+              kinds:
+                - Pod
+      exclude:
+        any:
+          - resources:
+              namespaces:
+                - kube-system
+                - kyverno
+      validate:
+        message: "CPU and memory limits are required. Add resources.limits.cpu and resources.limits.memory."
+        pattern:
+          spec:
+            containers:
+              - resources:
+                  limits:
+                    memory: "?*"
+                    cpu: "?*"