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kubernetes

Kubernetes YAML Examples: Deployments, Services, ConfigMaps

Intermediate
15 minutes
October 2026
CloudOpsGuide Team

Kubernetes YAML Examples: Deployments, Services, ConfigMaps

Collection of essential Kubernetes YAML templates with explanations for common deployment scenarios.

Table of Contents

Basic Deployment

Simple Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.25
        ports:
        - containerPort: 80
        resources:
          requests:
            memory: "64Mi"
            cpu: "250m"
          limits:
            memory: "128Mi"
            cpu: "500m"

Key Components:

  • replicas: Number of pod copies
  • selector: Matches pods to deployment
  • template: Pod template specification
  • resources: CPU and memory limits

Deployment with Environment Variables

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:latest
        env:
        - name: DATABASE_URL
          value: "postgresql://db:5432/mydb"
        - name: API_KEY
          valueFrom:
            secretKeyRef:
              name: app-secrets
              key: api-key
        - name: LOG_LEVEL
          value: "info"
        ports:
        - containerPort: 3000

Service Configuration

ClusterIP Service

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  type: ClusterIP
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80

NodePort Service

apiVersion: v1
kind: Service
metadata:
  name: nginx-nodeport
spec:
  type: NodePort
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
    nodePort: 30080

LoadBalancer Service

apiVersion: v1
kind: Service
metadata:
  name: nginx-loadbalancer
spec:
  type: LoadBalancer
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80

ConfigMap Usage

ConfigMap from Literal Values

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  database.host: "postgres"
  database.port: "5432"
  cache.ttl: "3600"
  app.debug: "false"

ConfigMap from File

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config
data:
  nginx.conf: |
    server {
      listen 80;
      server_name localhost;
      
      location / {
        root /usr/share/nginx/html;
        index index.html;
      }
    }

Using ConfigMap in Pod

apiVersion: v1
kind: Pod
metadata:
  name: configmap-pod
spec:
  containers:
  - name: app
    image: myapp:latest
    envFrom:
    - configMapRef:
        name: app-config
    volumeMounts:
    - name: config-volume
      mountPath: /etc/config
  volumes:
  - name: config-volume
    configMap:
      name: nginx-config

Secret Management

Creating Secret from Literal

kubectl create secret generic db-secret \
  --from-literal=username=admin \
  --from-literal=password=secret123

Secret YAML

apiVersion: v1
kind: Secret
metadata:
  name: db-secret
type: Opaque
data:
  username: YWRtaW4=  # base64 encoded "admin"
  password: c2VjcmV0MTIz  # base64 encoded "secret123"

Using Secret in Pod

apiVersion: v1
kind: Pod
metadata:
  name: secret-pod
spec:
  containers:
  - name: app
    image: myapp:latest
    env:
    - name: DB_USERNAME
      valueFrom:
        secretKeyRef:
          name: db-secret
          key: username
    - name: DB_PASSWORD
      valueFrom:
        secretKeyRef:
          name: db-secret
          key: password

Ingress Configuration

Basic Ingress

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: nginx-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: nginx-service
            port:
              number: 80

Ingress with TLS

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: tls-ingress
  annotations:
    cert-manager.io/cluster-issuer: "letsencrypt-prod"
spec:
  ingressClassName: nginx
  tls:
  - hosts:
    - example.com
    secretName: example-tls
  rules:
  - host: example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: nginx-service
            port:
              number: 80

Horizontal Pod Autoscaler

HPA Based on CPU

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: nginx-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: nginx-deployment
  minReplicas: 2
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 50

HPA Based on Memory

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: app-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: app-deployment
  minReplicas: 1
  maxReplicas: 5
  metrics:
  - type: Resource
    resource:
      name: memory
      target:
        type: Utilization
        averageUtilization: 70

StatefulSet Example

StatefulSet for Database

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: postgres
spec:
  serviceName: postgres
  replicas: 3
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
      - name: postgres
        image: postgres:15
        ports:
        - containerPort: 5432
          name: postgres
        volumeMounts:
        - name: postgres-storage
          mountPath: /var/lib/postgresql/data
        env:
        - name: POSTGRES_PASSWORD
          valueFrom:
            secretKeyRef:
              name: postgres-secret
              key: password
  volumeClaimTemplates:
  - metadata:
      name: postgres-storage
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 10Gi

DaemonSet Example

DaemonSet for Monitoring

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: node-exporter
spec:
  selector:
    matchLabels:
      app: node-exporter
  template:
    metadata:
      labels:
        app: node-exporter
    spec:
      hostNetwork: true
      containers:
      - name: node-exporter
        image: prom/node-exporter:latest
        ports:
        - containerPort: 9100
          hostPort: 9100
        resources:
          requests:
            memory: "64Mi"
            cpu: "100m"
          limits:
            memory: "128Mi"
            cpu: "200m"

Complete Example: Full Stack Application

Deployment + Service + ConfigMap + Secret

---
# ConfigMap
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  app.env: "production"
  app.port: "3000"
---
# Secret
apiVersion: v1
kind: Secret
metadata:
  name: app-secret
type: Opaque
data:
  db-password: c2VjcmV0
---
# Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: fullstack-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: fullstack
  template:
    metadata:
      labels:
        app: fullstack
    spec:
      containers:
      - name: app
        image: fullstack:latest
        ports:
        - containerPort: 3000
        envFrom:
        - configMapRef:
            name: app-config
        env:
        - name: DB_PASSWORD
          valueFrom:
            secretKeyRef:
              name: app-secret
              key: db-password
        resources:
          requests:
            memory: "128Mi"
            cpu: "250m"
          limits:
            memory: "256Mi"
            cpu: "500m"
        livenessProbe:
          httpGet:
            path: /health
            port: 3000
          initialDelaySeconds: 30
          periodSeconds: 10
        readinessProbe:
          httpGet:
            path: /ready
            port: 3000
          initialDelaySeconds: 5
          periodSeconds: 5
---
# Service
apiVersion: v1
kind: Service
metadata:
  name: fullstack-service
spec:
  type: ClusterIP
  selector:
    app: fullstack
  ports:
  - protocol: TCP
    port: 80
    targetPort: 3000
---
# HPA
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: fullstack-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: fullstack-app
  minReplicas: 3
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 70

Best Practices

  1. Always use labels - For identification and selection
  2. Set resource limits - Prevent resource exhaustion
  3. Use health checks - For automatic recovery
  4. Version your images - Avoid latest tag
  5. Use secrets for sensitive data - Never in ConfigMaps
  6. Document your YAML - Add comments
  7. Use kubectl dry-run - Validate before applying
  8. Use names consistently - Related resources
  9. Implement RBAC - For security
  10. Monitor your deployments - Set up alerts

Useful Commands

# Apply YAML file
kubectl apply -f deployment.yaml

# Validate without applying
kubectl apply --dry-run=client -f deployment.yaml

# Get YAML from running resource
kubectl get deployment nginx -o yaml

# Explain resource fields
kubectl explain deployment.spec.template.spec

# Delete resources
kubectl delete -f deployment.yaml

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Last Updated: October 2026
Author: CloudOpsGuide Team
Difficulty: Intermediate
Estimated Reading Time: 15 minutes