Tech Study Guide

Kubernetes Examples

Practical Kubernetes examples for Deployments, Services, PodDisruptionBudgets, NetworkPolicy, and StatefulSet storage.

examples kubernetes networkpolicy storage

Kubernetes Examples

These examples complement Kubernetes, NetworkPolicy, Services and EndpointSlices, and Storage and Upgrades.

Kubernetes Deployment Example

A Deployment with requests, limits, probes, rollout safety, and labels that can feed a Service:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: example-api
  namespace: apps
  labels:
    app.kubernetes.io/name: example-api
spec:
  replicas: 3
  revisionHistoryLimit: 5
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: example-api
  template:
    metadata:
      labels:
        app.kubernetes.io/name: example-api
    spec:
      containers:
        - name: api
          image: registry.example.com/example-api:1.4.2
          ports:
            - name: http
              containerPort: 8080
          resources:
            requests:
              cpu: 250m
              memory: 256Mi
            limits:
              cpu: "1"
              memory: 768Mi
          startupProbe:
            httpGet:
              path: /health/startup
              port: http
            failureThreshold: 30
            periodSeconds: 2
          readinessProbe:
            httpGet:
              path: /health/ready
              port: http
            periodSeconds: 5
          livenessProbe:
            httpGet:
              path: /health/live
              port: http
            periodSeconds: 10

Service and PodDisruptionBudget:

apiVersion: v1
kind: Service
metadata:
  name: example-api
  namespace: apps
spec:
  type: ClusterIP
  selector:
    app.kubernetes.io/name: example-api
  ports:
    - name: http
      port: 80
      targetPort: http
---
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: example-api
  namespace: apps
spec:
  minAvailable: 2
  selector:
    matchLabels:
      app.kubernetes.io/name: example-api

Kubernetes NetworkPolicy Example

A default-deny plus explicit app and DNS egress:

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: default-deny
  namespace: apps
spec:
  podSelector: {}
  policyTypes:
    - Ingress
    - Egress
---
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: example-api-allow
  namespace: apps
spec:
  podSelector:
    matchLabels:
      app.kubernetes.io/name: example-api
  policyTypes:
    - Ingress
    - Egress
  ingress:
    - from:
        - namespaceSelector:
            matchLabels:
              kubernetes.io/metadata.name: ingress
      ports:
        - protocol: TCP
          port: 8080
  egress:
    - to:
        - namespaceSelector:
            matchLabels:
              kubernetes.io/metadata.name: kube-system
      ports:
        - protocol: UDP
          port: 53
        - protocol: TCP
          port: 53
    - to:
        - namespaceSelector:
            matchLabels:
              kubernetes.io/metadata.name: databases
      ports:
        - protocol: TCP
          port: 5432

Kubernetes Storage Example

A StatefulSet with stable identity and a per-Pod PVC:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: queue
  namespace: apps
spec:
  serviceName: queue-headless
  replicas: 3
  selector:
    matchLabels:
      app.kubernetes.io/name: queue
  template:
    metadata:
      labels:
        app.kubernetes.io/name: queue
    spec:
      containers:
        - name: queue
          image: registry.example.com/queue:2.1.0
          volumeMounts:
            - name: data
              mountPath: /var/lib/queue
  volumeClaimTemplates:
    - metadata:
        name: data
      spec:
        accessModes:
          - ReadWriteOnce
        storageClassName: fast-ssd
        resources:
          requests:
            storage: 50Gi

Study Cards

Question

What makes a Kubernetes Deployment example operationally useful?

Answer

It shows selectors, resources, probes, rollout behavior, and how traffic attaches to the workload.

Question

Why pair a Service selector with stable labels?

Answer

Service endpoints are derived from matching Pods, so labels are the contract between workload and traffic routing.

Question

Why include DNS egress in a default-deny NetworkPolicy example?

Answer

Most applications need name resolution, and default-deny egress breaks DNS unless it is explicitly allowed.

References