Kubernetes Deployment Patterns
Basic Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
name: myapp
labels:
app: myapp
spec:
replicas: 3
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:1.0.0
ports:
- containerPort: 8080
resources:
requests:
memory: "256Mi"
cpu: "250m"
limits:
memory: "512Mi"
cpu: "500m"
Service (LoadBalancer)
apiVersion: v1
kind: Service
metadata:
name: myapp-service
spec:
type: LoadBalancer
selector:
app: myapp
ports:
- port: 80
targetPort: 8080
protocol: TCP
Service (ClusterIP - Internal)
apiVersion: v1
kind: Service
metadata:
name: myapp-internal
spec:
type: ClusterIP
selector:
app: myapp
ports:
- port: 8080
targetPort: 8080
ConfigMap
apiVersion: v1
kind: ConfigMap
metadata:
name: myapp-config
data:
database_host: "postgres.default.svc.cluster.local"
database_port: "5432"
log_level: "info"
config.json: |
{
"feature_flags": {
"new_ui": true
}
}
Secret
apiVersion: v1
kind: Secret
metadata:
name: myapp-secrets
type: Opaque
stringData:
database_password: "changeme"
api_key: "secret-api-key"
jwt_secret: "jwt-secret-key"
Deployment with ConfigMap and Secret
apiVersion: apps/v1
kind: Deployment
metadata:
name: myapp
spec:
replicas: 3
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
- name: myapp
image: myapp:1.0.0
ports:
- containerPort: 8080
env:
- name: DATABASE_HOST
valueFrom:
configMapKeyRef:
name: myapp-config
key: database_host
- name: DATABASE_PASSWORD
valueFrom:
secretKeyRef:
name: myapp-secrets
key: database_password
volumeMounts:
- name: config
mountPath: /app/config
readOnly: true
volumes:
- name: config
configMap:
name: myapp-config
Ingress (NGINX)
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: myapp-ingress
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
cert-manager.io/cluster-issuer: "letsencrypt-prod"
spec:
tls:
- hosts:
- myapp.example.com
secretName: myapp-tls
rules:
- host: myapp.example.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: myapp-service
port:
number: 80
Horizontal Pod Autoscaler
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
name: myapp-hpa
spec:
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: myapp
minReplicas: 2
maxReplicas: 10
metrics:
- type: Resource
resource:
name: cpu
target:
type: Utilization
averageUtilization: 70
- type: Resource
resource:
name: memory
target:
type: Utilization
averageUtilization: 80
PersistentVolumeClaim
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: myapp-pvc
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
storageClassName: standard
StatefulSet (for databases)
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: postgres
spec:
serviceName: postgres
replicas: 1
selector:
matchLabels:
app: postgres
template:
metadata:
labels:
app: postgres
spec:
containers:
- name: postgres
image: postgres:15
ports:
- containerPort: 5432
env:
- name: POSTGRES_PASSWORD
valueFrom:
secretKeyRef:
name: postgres-secret
key: password
volumeMounts:
- name: postgres-data
mountPath: /var/lib/postgresql/data
volumeClaimTemplates:
- metadata:
name: postgres-data
spec:
accessModes: ["ReadWriteOnce"]
resources:
requests:
storage: 20Gi
Job (One-time task)
apiVersion: batch/v1
kind: Job
metadata:
name: database-migration
spec:
template:
spec:
containers:
- name: migrate
image: myapp:1.0.0
command: ["python", "manage.py", "migrate"]
env:
- name: DATABASE_URL
valueFrom:
secretKeyRef:
name: myapp-secrets
key: database_url
restartPolicy: Never
backoffLimit: 3
CronJob
apiVersion: batch/v1
kind: CronJob
metadata:
name: backup-job
spec:
schedule: "0 2 * * *" # Daily at 2 AM
jobTemplate:
spec:
template:
spec:
containers:
- name: backup
image: myapp:1.0.0
command: ["python", "backup.py"]
restartPolicy: OnFailure
Health Probes
apiVersion: apps/v1
kind: Deployment
metadata:
name: myapp
spec:
template:
spec:
containers:
- name: myapp
image: myapp:1.0.0
ports:
- containerPort: 8080
livenessProbe:
httpGet:
path: /health
port: 8080
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
failureThreshold: 3
readinessProbe:
httpGet:
path: /ready
port: 8080
initialDelaySeconds: 10
periodSeconds: 5
timeoutSeconds: 3
successThreshold: 1
failureThreshold: 3
startupProbe:
httpGet:
path: /startup
port: 8080
initialDelaySeconds: 0
periodSeconds: 10
timeoutSeconds: 3
failureThreshold: 30
Resource Quotas
apiVersion: v1
kind: ResourceQuota
metadata:
name: myapp-quota
namespace: production
spec:
hard:
requests.cpu: "10"
requests.memory: 20Gi
limits.cpu: "20"
limits.memory: 40Gi
persistentvolumeclaims: "5"
NetworkPolicy
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: myapp-network-policy
spec:
podSelector:
matchLabels:
app: myapp
policyTypes:
- Ingress
- Egress
ingress:
- from:
- podSelector:
matchLabels:
role: frontend
ports:
- protocol: TCP
port: 8080
egress:
- to:
- podSelector:
matchLabels:
app: postgres
ports:
- protocol: TCP
port: 5432
Multi-Container Pod
apiVersion: v1
kind: Pod
metadata:
name: myapp-pod
spec:
containers:
- name: app
image: myapp:1.0.0
ports:
- containerPort: 8080
volumeMounts:
- name: shared-data
mountPath: /app/data
- name: sidecar
image: logging-sidecar:1.0.0
volumeMounts:
- name: shared-data
mountPath: /data
volumes:
- name: shared-data
emptyDir: {}
Init Containers
apiVersion: apps/v1
kind: Deployment
metadata:
name: myapp
spec:
template:
spec:
initContainers:
- name: wait-for-db
image: busybox:1.35
command: ['sh', '-c', 'until nc -z postgres 5432; do sleep 2; done']
- name: run-migrations
image: myapp:1.0.0
command: ['python', 'manage.py', 'migrate']
containers:
- name: myapp
image: myapp:1.0.0
Best Practices
Resource Management
resources:
requests:
memory: "256Mi" # Guaranteed allocation
cpu: "250m" # 0.25 CPU cores
limits:
memory: "512Mi" # Maximum allowed
cpu: "500m" # 0.5 CPU cores
Rolling Updates
spec:
strategy:
type: RollingUpdate
rollingUpdate:
maxSurge: 1 # Max pods above desired count
maxUnavailable: 0 # Max pods unavailable during update
Pod Disruption Budget
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
name: myapp-pdb
spec:
minAvailable: 2
selector:
matchLabels:
app: myapp
Affinity and Anti-Affinity
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 100
podAffinityTerm:
labelSelector:
matchLabels:
app: myapp
topologyKey: kubernetes.io/hostname
Common Commands
# Apply configuration
kubectl apply -f deployment.yaml
# Get resources
kubectl get deployments
kubectl get pods
kubectl get services
# Describe resource
kubectl describe deployment myapp
# View logs
kubectl logs -f deployment/myapp
# Scale deployment
kubectl scale deployment myapp --replicas=5
# Update image
kubectl set image deployment/myapp myapp=myapp:2.0.0
# Rollback
kubectl rollout undo deployment/myapp
# Port forward
kubectl port-forward deployment/myapp 8080:8080
# Execute command in pod
kubectl exec -it pod/myapp-xxx -- /bin/sh
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