Kubernetes Security

Security best practices for Kubernetes deployments.

Pod Security

Run as Non-Root

spec:
  securityContext:
    runAsNonRoot: true
    runAsUser: 1000
    fsGroup: 1000

Read-Only Root Filesystem

spec:
  containers:
  - name: app
    securityContext:
      readOnlyRootFilesystem: true
    volumeMounts:
    - name: tmp
      mountPath: /tmp
  volumes:
  - name: tmp
    emptyDir: {}

Drop Capabilities

spec:
  containers:
  - name: app
    securityContext:
      capabilities:
        drop:
        - ALL
        add:
        - NET_BIND_SERVICE

Prevent Privilege Escalation

spec:
  containers:
  - name: app
    securityContext:
      allowPrivilegeEscalation: false
      privileged: false

Network Security

Network Policies

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: api-allow
spec:
  podSelector:
    matchLabels:
      app: api
  policyTypes:
  - Ingress
  - Egress
  ingress:
  - from:
    - podSelector:
        matchLabels:
          app: frontend
    ports:
    - protocol: TCP
      port: 8080
  egress:
  - to:
    - podSelector:
        matchLabels:
          app: database
    ports:
    - protocol: TCP
      port: 5432

RBAC

ServiceAccount

apiVersion: v1
kind: ServiceAccount
metadata:
  name: app-sa
  namespace: default

Role

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: pod-reader
rules:
- apiGroups: [""]
  resources: ["pods"]
  verbs: ["get", "list"]

RoleBinding

apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: read-pods
subjects:
- kind: ServiceAccount
  name: app-sa
  namespace: default
roleRef:
  kind: Role
  name: pod-reader
  apiGroup: rbac.authorization.k8s.io

Secrets Management

Encrypt at Rest

Enable encryption for secrets at rest in etcd.

External Secrets

Use external secret management:

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: app-secrets
spec:
  refreshInterval: 1h
  secretStoreRef:
    name: vault-backend
    kind: SecretStore
  target:
    name: app-secrets
  data:
  - secretKey: password
    remoteRef:
      key: secret/data/app
      property: password

Avoid Hardcoding

# Bad
env:
- name: DB_PASSWORD
  value: "hardcoded-password"

# Good
env:
- name: DB_PASSWORD
  valueFrom:
    secretKeyRef:
      name: db-secret
      key: password

Resource Limits

Prevent Resource Exhaustion

spec:
  containers:
  - name: app
    resources:
      limits:
        memory: "256Mi"
        cpu: "500m"
      requests:
        memory: "128Mi"
        cpu: "250m"

LimitRange

apiVersion: v1
kind: LimitRange
metadata:
  name: mem-limit-range
spec:
  limits:
  - max:
      memory: 512Mi
    min:
      memory: 64Mi
    type: Container

ResourceQuota

apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-quota
spec:
  hard:
    requests.cpu: "10"
    requests.memory: 20Gi
    limits.cpu: "20"
    limits.memory: 40Gi

Image Security

Use Specific Tags

# Bad
image: nginx:latest

# Good
image: nginx:1.21.6

Image Pull Policies

spec:
  containers:
  - name: app
    image: myapp:1.0.0
    imagePullPolicy: IfNotPresent

Private Registries

spec:
  imagePullSecrets:
  - name: registry-credentials
  containers:
  - name: app
    image: private.registry.com/myapp:1.0.0

Pod Security Standards

Restricted Profile

apiVersion: v1
kind: Namespace
metadata:
  name: production
  labels:
    pod-security.kubernetes.io/enforce: restricted
    pod-security.kubernetes.io/audit: restricted
    pod-security.kubernetes.io/warn: restricted

Security Scanning

# Scan manifests with kubesec
kubesec scan pod.yaml

# Scan images with trivy
trivy image nginx:1.21

# Policy validation with OPA
opa eval -d policy.rego -i manifest.yaml