feat(security): add Pod Security Standards (PSA) namespace configurations

- Add namespace templates for privileged, baseline, and restricted levels
- Include compliant deployment examples for baseline and restricted
- Add migration audit script for checking namespace compliance
- Document PSA levels, enforcement modes, and migration strategy

Follows Kubernetes Pod Security Admission best practices for 2025+.
Reference: https://kubernetes.io/docs/concepts/security/pod-security-standards/

README.md

@@ -15,12 +15,14 @@ Production-ready Kubernetes manifests with security best practices, resource lim
 ├── secrets/           # Secret management patterns
 ├── networkpolicies/   # Network isolation
 ├── rbac/              # Role-based access control
-└── monitoring/        # Prometheus, alerts, ServiceMonitors
+├── monitoring/        # Prometheus, alerts, ServiceMonitors
+└── pod-security/      # Pod Security Standards (PSA) configuration
 ```
 
 ## Features
 
 - ✅ Security contexts and pod security standards
+- ✅ **Pod Security Admission (PSA)** namespace configurations
 - ✅ Resource requests/limits
 - ✅ Liveness/readiness probes
 - ✅ Network policies for isolation

pod-security/README.md

@@ -0,0 +1,57 @@
+# Pod Security Standards (PSS) Configuration
+
+Kubernetes Pod Security Admission (PSA) enforces the [Pod Security Standards](https://kubernetes.io/docs/concepts/security/pod-security-standards/) at the namespace level.
+
+## Security Levels
+
+| Level | Description | Use Case |
+|-------|-------------|----------|
+| **Privileged** | Unrestricted, allows all capabilities | System workloads, CNI, monitoring agents |
+| **Baseline** | Prevents known privilege escalations | Most application workloads |
+| **Restricted** | Hardened, follows best practices | Sensitive/untrusted workloads |
+
+## Enforcement Modes
+
+- `enforce` - Rejects pods that violate the policy
+- `audit` - Logs violations but allows pods
+- `warn` - Sends warnings to users but allows pods
+
+## Quick Start
+
+```bash
+# Apply all namespace configurations
+kubectl apply -f namespaces/
+
+# Test a deployment against restricted namespace
+kubectl apply -f examples/restricted-deployment.yaml -n restricted-apps
+```
+
+## Namespace Configuration
+
+Each namespace is configured with PSA labels:
+
+```yaml
+labels:
+  pod-security.kubernetes.io/enforce: restricted
+  pod-security.kubernetes.io/enforce-version: latest
+  pod-security.kubernetes.io/audit: restricted
+  pod-security.kubernetes.io/warn: restricted
+```
+
+## Migration Strategy
+
+1. Start with `audit` and `warn` modes to identify violations
+2. Fix non-compliant workloads
+3. Enable `enforce` mode
+
+## Files
+
+- `namespaces/` - Pre-configured namespaces for each security level
+- `examples/` - Compliant deployment examples for each level
+- `migration/` - Tools for auditing existing namespaces
+
+## References
+
+- [Pod Security Standards](https://kubernetes.io/docs/concepts/security/pod-security-standards/)
+- [Pod Security Admission](https://kubernetes.io/docs/concepts/security/pod-security-admission/)
+- [Migrate from PSP](https://kubernetes.io/docs/tasks/configure-pod-container/migrate-from-psp/)

pod-security/examples/baseline-deployment.yaml

@@ -0,0 +1,74 @@
+# Example deployment compliant with BASELINE Pod Security Standard
+# Suitable for most application workloads
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: standard-app
+  namespace: baseline-apps
+  labels:
+    app: standard-app
+    security.kubernetes.io/compliant: "baseline"
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app: standard-app
+  template:
+    metadata:
+      labels:
+        app: standard-app
+    spec:
+      # Baseline allows running as root, but we still recommend non-root
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 1000
+        fsGroup: 1000
+        seccompProfile:
+          type: RuntimeDefault
+
+      containers:
+        - name: app
+          image: nginx:1.27
+          ports:
+            - containerPort: 80
+              protocol: TCP
+
+          securityContext:
+            allowPrivilegeEscalation: false
+            # Baseline allows writable root filesystem
+            # readOnlyRootFilesystem: false  # default
+            capabilities:
+              drop:
+                - ALL
+              add:
+                # Baseline allows these capabilities
+                - NET_BIND_SERVICE
+                - CHOWN
+                - SETGID
+                - SETUID
+
+          resources:
+            requests:
+              cpu: 100m
+              memory: 128Mi
+            limits:
+              cpu: 500m
+              memory: 256Mi
+
+          livenessProbe:
+            httpGet:
+              path: /
+              port: 80
+            initialDelaySeconds: 10
+            periodSeconds: 10
+
+          readinessProbe:
+            httpGet:
+              path: /
+              port: 80
+            initialDelaySeconds: 5
+            periodSeconds: 5
+
+      # Service account with minimal permissions
+      serviceAccountName: default
+      automountServiceAccountToken: false

pod-security/examples/restricted-deployment.yaml

@@ -0,0 +1,105 @@
+# Example deployment compliant with RESTRICTED Pod Security Standard
+# This is the gold standard for secure workloads
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: secure-app
+  namespace: restricted-apps
+  labels:
+    app: secure-app
+    security.kubernetes.io/compliant: "restricted"
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app: secure-app
+  template:
+    metadata:
+      labels:
+        app: secure-app
+    spec:
+      # Pod-level security context
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 65534          # nobody user
+        runAsGroup: 65534
+        fsGroup: 65534
+        seccompProfile:
+          type: RuntimeDefault
+
+      # Prevent service account token auto-mount unless needed
+      automountServiceAccountToken: false
+
+      containers:
+        - name: app
+          image: nginx:1.27-alpine
+          ports:
+            - containerPort: 8080
+              protocol: TCP
+
+          # Container-level security context
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            runAsNonRoot: true
+            runAsUser: 65534
+            capabilities:
+              drop:
+                - ALL
+              # Only add NET_BIND_SERVICE if binding to ports < 1024
+              # add:
+              #   - NET_BIND_SERVICE
+
+          # Resource limits (required for production)
+          resources:
+            requests:
+              cpu: 100m
+              memory: 128Mi
+            limits:
+              cpu: 500m
+              memory: 256Mi
+
+          # Probes for reliability
+          livenessProbe:
+            httpGet:
+              path: /healthz
+              port: 8080
+            initialDelaySeconds: 10
+            periodSeconds: 10
+
+          readinessProbe:
+            httpGet:
+              path: /ready
+              port: 8080
+            initialDelaySeconds: 5
+            periodSeconds: 5
+
+          # Volume mounts for writable paths (since root is read-only)
+          volumeMounts:
+            - name: tmp
+              mountPath: /tmp
+            - name: cache
+              mountPath: /var/cache/nginx
+            - name: run
+              mountPath: /var/run
+
+      volumes:
+        # EmptyDir for ephemeral writable storage
+        - name: tmp
+          emptyDir:
+            sizeLimit: 100Mi
+        - name: cache
+          emptyDir:
+            sizeLimit: 100Mi
+        - name: run
+          emptyDir:
+            sizeLimit: 10Mi
+
+      # Topology spread for high availability
+      topologySpreadConstraints:
+        - maxSkew: 1
+          topologyKey: kubernetes.io/hostname
+          whenUnsatisfiable: ScheduleAnyway
+          labelSelector:
+            matchLabels:
+              app: secure-app

pod-security/migration/audit-namespaces.sh

@@ -0,0 +1,52 @@
+#!/bin/bash
+# audit-namespaces.sh - Check PSA compliance across all namespaces
+# Usage: ./audit-namespaces.sh [restricted|baseline]
+
+set -euo pipefail
+
+LEVEL="${1:-restricted}"
+
+echo "=== Pod Security Standards Compliance Audit ==="
+echo "Target level: $LEVEL"
+echo "Date: $(date -u +%Y-%m-%dT%H:%M:%SZ)"
+echo ""
+
+# Get all namespaces
+NAMESPACES=$(kubectl get namespaces -o jsonpath='{.items[*].metadata.name}')
+
+for NS in $NAMESPACES; do
+  # Skip system namespaces
+  if [[ "$NS" == "kube-system" || "$NS" == "kube-public" || "$NS" == "kube-node-lease" ]]; then
+    echo "[$NS] SKIPPED (system namespace)"
+    continue
+  fi
+
+  # Check current PSA labels
+  CURRENT_LEVEL=$(kubectl get namespace "$NS" -o jsonpath='{.metadata.labels.pod-security\.kubernetes\.io/enforce}' 2>/dev/null || echo "none")
+
+  # Dry-run label to check violations
+  echo ""
+  echo "=== Namespace: $NS (current: $CURRENT_LEVEL) ==="
+
+  # Use --dry-run to preview what would be blocked
+  kubectl label namespace "$NS" \
+    "pod-security.kubernetes.io/enforce=$LEVEL" \
+    "pod-security.kubernetes.io/warn=$LEVEL" \
+    --dry-run=server \
+    --overwrite 2>&1 | grep -E "(Warning|Error)" || echo "✓ No violations detected"
+
+  # List pods that might violate
+  echo ""
+  echo "Pods in namespace:"
+  kubectl get pods -n "$NS" -o wide --no-headers 2>/dev/null | head -5 || echo "  (no pods)"
+done
+
+echo ""
+echo "=== Audit Complete ==="
+echo ""
+echo "To apply restricted level to a namespace:"
+echo "  kubectl label namespace <name> \\"
+echo "    pod-security.kubernetes.io/enforce=restricted \\"
+echo "    pod-security.kubernetes.io/audit=restricted \\"
+echo "    pod-security.kubernetes.io/warn=restricted \\"
+echo "    --overwrite"

pod-security/namespaces/baseline.yaml

@@ -0,0 +1,30 @@
+# Baseline namespace - for most application workloads
+# Prevents known privilege escalations while allowing common configurations
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: baseline-apps
+  labels:
+    # PSA labels - baseline enforcement with restricted auditing
+    pod-security.kubernetes.io/enforce: baseline
+    pod-security.kubernetes.io/enforce-version: latest
+    pod-security.kubernetes.io/audit: restricted    # Audit at higher level
+    pod-security.kubernetes.io/audit-version: latest
+    pod-security.kubernetes.io/warn: restricted     # Warn about restricted violations
+    pod-security.kubernetes.io/warn-version: latest
+    # Metadata
+    environment: production
+    security-level: baseline
+  annotations:
+    description: "Baseline security for standard application workloads"
+---
+# Baseline allows:
+# - Default container configurations
+# - Non-privileged containers
+# - Standard capabilities (NET_BIND_SERVICE, etc.)
+#
+# Baseline blocks:
+# - Privileged containers
+# - Host namespaces (hostPID, hostIPC, hostNetwork)
+# - Host path volumes
+# - Privileged capabilities

pod-security/namespaces/privileged.yaml

@@ -0,0 +1,25 @@
+# Privileged namespace - for system-level workloads only
+# Use sparingly: CNI plugins, monitoring agents, storage drivers
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: privileged-system
+  labels:
+    # PSA labels - privileged level
+    pod-security.kubernetes.io/enforce: privileged
+    pod-security.kubernetes.io/enforce-version: latest
+    pod-security.kubernetes.io/audit: privileged
+    pod-security.kubernetes.io/warn: privileged
+    # Metadata
+    environment: system
+    security-level: privileged
+  annotations:
+    description: "Privileged namespace for system workloads requiring host access"
+---
+# Example: kube-system should typically be privileged
+# To label an existing namespace:
+# kubectl label namespace kube-system \
+#   pod-security.kubernetes.io/enforce=privileged \
+#   pod-security.kubernetes.io/audit=privileged \
+#   pod-security.kubernetes.io/warn=privileged \
+#   --overwrite

pod-security/namespaces/restricted.yaml

@@ -0,0 +1,34 @@
+# Restricted namespace - maximum security hardening
+# For sensitive workloads and untrusted code
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: restricted-apps
+  labels:
+    # PSA labels - restricted at all levels
+    pod-security.kubernetes.io/enforce: restricted
+    pod-security.kubernetes.io/enforce-version: latest
+    pod-security.kubernetes.io/audit: restricted
+    pod-security.kubernetes.io/audit-version: latest
+    pod-security.kubernetes.io/warn: restricted
+    pod-security.kubernetes.io/warn-version: latest
+    # Metadata
+    environment: production
+    security-level: restricted
+  annotations:
+    description: "Restricted security for sensitive and untrusted workloads"
+---
+# Restricted REQUIRES:
+# - runAsNonRoot: true
+# - allowPrivilegeEscalation: false
+# - Drop ALL capabilities (except NET_BIND_SERVICE)
+# - seccompProfile: RuntimeDefault or Localhost
+# - Read-only root filesystem (recommended)
+#
+# Restricted BLOCKS:
+# - Everything baseline blocks, plus:
+# - Running as root
+# - Privilege escalation
+# - Most capabilities
+# - HostPath volumes
+# - Writable root filesystems (warning only)