2329 Kubernetes 6c039268

# Kubernetes Patterns

## Deployment

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app
  labels:
    app.kubernetes.io/name: app
    app.kubernetes.io/component: backend
spec:
  replicas: 3
  selector:
    matchLabels:
      app.kubernetes.io/name: app
  template:
    metadata:
      labels:
        app.kubernetes.io/name: app
    spec:
      securityContext:
        runAsNonRoot: true
        runAsUser: 1000
        fsGroup: 1000
      containers:
        - name: app
          image: app:latest
          ports:
            - containerPort: 8080
          resources:
            requests:
              cpu: 100m
              memory: 128Mi
            limits:
              cpu: 500m
              memory: 512Mi
          securityContext:
            allowPrivilegeEscalation: false
            readOnlyRootFilesystem: true
            capabilities:
              drop: [ALL]
          livenessProbe:
            httpGet:
              path: /health
              port: 8080
            initialDelaySeconds: 10
          readinessProbe:
            httpGet:
              path: /ready
              port: 8080
```

## Service

```yaml
apiVersion: v1
kind: Service
metadata:
  name: app
spec:
  selector:
    app.kubernetes.io/name: app
  ports:
    - port: 80
      targetPort: 8080
  type: ClusterIP
```

## ConfigMap

```yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  LOG_LEVEL: info
  FEATURE_FLAG: "true"
```

## Secret

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: app-secrets
type: Opaque
stringData:
  DATABASE_URL: postgres://user:pass@host/db
```

## Kustomize Structure

```
base/
├── kustomization.yaml
├── deployment.yaml
├── service.yaml
└── configmap.yaml
overlays/
├── dev/
│   ├── kustomization.yaml
│   └── patch-replicas.yaml
└── prod/
    ├── kustomization.yaml
    └── patch-replicas.yaml
```

### base/kustomization.yaml

```yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - deployment.yaml
  - service.yaml
  - configmap.yaml
```

### overlays/prod/kustomization.yaml

```yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - ../../base
namespace: production
patches:
  - path: patch-replicas.yaml
```

### overlays/prod/patch-replicas.yaml

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app
spec:
  replicas: 5
```

## Network Policy

```yaml
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: app-network-policy
spec:
  podSelector:
    matchLabels:
      app.kubernetes.io/name: app
  policyTypes:
    - Ingress
    - Egress
  ingress:
    - from:
        - podSelector:
            matchLabels:
              app.kubernetes.io/name: frontend
      ports:
        - port: 8080
  egress:
    - to:
        - podSelector:
            matchLabels:
              app.kubernetes.io/name: database
      ports:
        - port: 5432
```

## HPA

```yaml
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: app
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: app
  minReplicas: 2
  maxReplicas: 10
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 70
```

## Standard Labels

```yaml
labels:
  app.kubernetes.io/name: myapp
  app.kubernetes.io/instance: myapp-prod
  app.kubernetes.io/version: "1.0.0"
  app.kubernetes.io/component: backend
  app.kubernetes.io/part-of: myplatform
  app.kubernetes.io/managed-by: helm
```