Intermediate Estimated time: 6 min Category: Cybersecurity Published

Zero Trust in Practice¶

Roll out strong identities, mTLS, least-privilege access control and continuous posture validation.

Core Principles¶

Identity first (workload identity with SPIFFE/SPIRE)
End-to-end mTLS (service ↔ service)
Least privilege (RBAC/ABAC, admission policies)
Segmentation (NetworkPolicies, egress control)
Continuous verification (scanning and posture)

Service Identities (SPIFFE/SPIRE)¶

# Install SPIRE Server/Agent (official Helm chart)
helm repo add spiffe https://spiffe.github.io/helm-charts
helm install spire spiffe/spire -n spire --create-namespace

# Example of a SPIFFE ID issued to a deployment
kubectl apply -f - <<'EOF'
apiVersion: spire.spiffe.io/v1alpha1
kind: SpiffeID
metadata:
  name: api-frontend
  namespace: default
spec:
  spiffeId: spiffe://example.org/ns/default/sa/api-frontend
  parentId: spiffe://example.org/spire/server
  selector:
    matchLabels:
      app: api-frontend
EOF

mTLS with a Service Mesh (Istio)¶

# Strict mTLS policy in the "prod" namespace
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: default
  namespace: prod
spec:
  mtls:
    mode: STRICT

# Least-privilege AuthorizationPolicy
apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: allow-frontend-to-api
  namespace: prod
spec:
  selector:
    matchLabels:
      app: api
  rules:
  - from:
    - source:
        principals: ["spiffe://example.org/ns/prod/sa/frontend"]
    to:
    - operation:
        ports: ["8080"]

Network Segmentation¶

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: allow-frontend-to-api
  namespace: prod
spec:
  podSelector:
    matchLabels:
      app: api
  policyTypes: [Ingress, Egress]
  ingress:
  - from:
    - podSelector:
        matchLabels:
          app: frontend
    ports:
    - protocol: TCP
      port: 8080
  egress:
  - to:
    - namespaceSelector: {}
    ports:
    - protocol: TCP
      port: 443

Admission Policies (OPA Gatekeeper)¶

apiVersion: constraints.gatekeeper.sh/v1beta1
kind: K8sRequireLabels
metadata:
  name: require-owner-tier
spec:
  match:
    kinds:
      - apiGroups: [""]
        kinds: ["Pod"]
  parameters:
    labels: ["owner", "tier"]

Continuous Posture¶

Scan images and manifests (Trivy, Checkov)
Review RBAC periodically (rbacker/ rbac-police)
Detect drift against a baseline (Kyverno policies in audit/enforce mode)

Quick Checklist¶

mTLS mandatory between services
Workload identities (SPIFFE/SPIRE) issued and verified
NetworkPolicies default to deny-all plus minimal rules
Admission policies for labels, limits and image signatures
Continuous image/manifest scanning and RBAC review