kubernetes-manifest-generator

Imported from dhandebaz/sangathan (.agents/skills/kubernetes-manifest-generator/SKILL.md). Install upstream with npx skills add dhandebaz/sangathan --skill kubernetes-manifest-generator. Copyright stays with the author.

Kubernetes Manifest Generator

Generate production-ready Kubernetes manifests with security and scalability best practices.

Core Workflow

1. Define resources: Identify required K8s objects
2. Create namespace: Isolate application resources
3. Configure deployments: Pods, replicas, resources
4. Setup services: Networking and load balancing
5. Add ingress: External access routing
6. Configure scaling: HPA and resource limits

Deployment Manifest

# k8s/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-deployment
  namespace: production
  labels:
    app: myapp
    version: v1
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  template:
    metadata:
      labels:
        app: myapp
        version: v1
      annotations:
        prometheus.io/scrape: "true"
        prometheus.io/port: "9090"
    spec:
      serviceAccountName: myapp-sa
      securityContext:
        runAsNonRoot: true
        runAsUser: 1000
        fsGroup: 1000
      containers:
        - name: app
          image: myregistry/myapp:v1.0.0
          imagePullPolicy: Always
          ports:
            - name: http
              containerPort: 3000
              protocol: TCP
            - name: metrics
              containerPort: 9090
              protocol: TCP
          env:
            - name: NODE_ENV
              value: production
            - name: DATABASE_URL
              valueFrom:
                secretKeyRef:
                  name: app-secrets
                  key: database-url
            - name: REDIS_HOST
              valueFrom:
                configMapKeyRef:
                  name: app-config
                  key: redis-host
          resources:
            requests:
              cpu: 100m
              memory: 128Mi
            limits:
              cpu: 500m
              memory: 512Mi
          livenessProbe:
            httpGet:
              path: /health/live
              port: http
            initialDelaySeconds: 30
            periodSeconds: 10
            timeoutSeconds: 5
            failureThreshold: 3
          readinessProbe:
            httpGet:
              path: /health/ready
              port: http
            initialDelaySeconds: 5
            periodSeconds: 5
            timeoutSeconds: 3
            failureThreshold: 3
          securityContext:
            allowPrivilegeEscalation: false
            readOnlyRootFilesystem: true
            capabilities:
              drop:
                - ALL
          volumeMounts:
            - name: tmp
              mountPath: /tmp
            - name: config
              mountPath: /app/config
              readOnly: true
      volumes:
        - name: tmp
          emptyDir: {}
        - name: config
          configMap:
            name: app-config
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
            - weight: 100
              podAffinityTerm:
                labelSelector:
                  matchLabels:
                    app: myapp
                topologyKey: kubernetes.io/hostname
      topologySpreadConstraints:
        - maxSkew: 1
          topologyKey: topology.kubernetes.io/zone
          whenUnsatisfiable: ScheduleAnyway
          labelSelector:
            matchLabels:
              app: myapp

Service Manifest

# k8s/service.yaml
apiVersion: v1
kind: Service
metadata:
  name: app-service
  namespace: production
  labels:
    app: myapp
spec:
  type: ClusterIP
  selector:
    app: myapp
  ports:
    - name: http
      port: 80
      targetPort: http
      protocol: TCP
    - name: metrics
      port: 9090
      targetPort: metrics
      protocol: TCP
---
# Headless service for StatefulSet
apiVersion: v1
kind: Service
metadata:
  name: app-headless
  namespace: production
spec:
  type: ClusterIP
  clusterIP: None
  selector:
    app: myapp
  ports:
    - name: http
      port: 80
      targetPort: http

Ingress Configuration

# k8s/ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: app-ingress
  namespace: production
  annotations:
    kubernetes.io/ingress.class: nginx
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/ssl-redirect: "true"
    nginx.ingress.kubernetes.io/rate-limit: "100"
    nginx.ingress.kubernetes.io/rate-limit-window: "1m"
    nginx.ingress.kubernetes.io/proxy-body-size: "10m"
    nginx.ingress.kubernetes.io/proxy-read-timeout: "60"
spec:
  tls:
    - hosts:
        - app.example.com
        - api.example.com
      secretName: app-tls-secret
  rules:
    - host: app.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: app-service
                port:
                  number: 80
    - host: api.example.com
      http:
        paths:
          - path: /api
            pathType: Prefix
            backend:
              service:
                name: api-service
                port:
                  number: 80

ConfigMap and Secrets

# k8s/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
  namespace: production
data:
  redis-host: redis-master.redis.svc.cluster.local
  log-level: info
  feature-flags: |
    {
      "newFeature": true,
      "betaAccess": false
    }
---
# k8s/secret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: app-secrets
  namespace: production
type: Opaque
stringData:
  database-url: postgresql://user:pass@host:5432/db
  api-key: your-api-key-here
---
# External Secrets (with external-secrets operator)
apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: app-external-secrets
  namespace: production
spec:
  refreshInterval: 1h
  secretStoreRef:
    name: aws-secrets-manager
    kind: ClusterSecretStore
  target:
    name: app-secrets
    creationPolicy: Owner
  data:
    - secretKey: database-url
      remoteRef:
        key: production/myapp/database
        property: url

Horizontal Pod Autoscaler

# k8s/hpa.yaml
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: app-hpa
  namespace: production
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: app-deployment
  minReplicas: 3
  maxReplicas: 20
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 70
    - type: Resource
      resource:
        name: memory
        target:
          type: Utilization
          averageUtilization: 80
    - type: Pods
      pods:
        metric:
          name: http_requests_per_second
        target:
          type: AverageValue
          averageValue: 1000
  behavior:
    scaleDown:
      stabilizationWindowSeconds: 300
      policies:
        - type: Percent
          value: 10
          periodSeconds: 60
    scaleUp:
      stabilizationWindowSeconds: 0
      policies:
        - type: Percent
          value: 100
          periodSeconds: 15
        - type: Pods
          value: 4
          periodSeconds: 15
      selectPolicy: Max

Pod Disruption Budget

# k8s/pdb.yaml
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: app-pdb
  namespace: production
spec:
  minAvailable: 2
  selector:
    matchLabels:
      app: myapp

Network Policy

# k8s/network-policy.yaml
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: app-network-policy
  namespace: production
spec:
  podSelector:
    matchLabels:
      app: myapp
  policyTypes:
    - Ingress
    - Egress
  ingress:
    - from:
        - namespaceSelector:
            matchLabels:
              name: ingress-nginx
        - podSelector:
            matchLabels:
              app: frontend
      ports:
        - protocol: TCP
          port: 3000
  egress:
    - to:
        - namespaceSelector:
            matchLabels:
              name: database
      ports:
        - protocol: TCP
          port: 5432
    - to:
        - namespaceSelector:
            matchLabels:
              name: redis
      ports:
        - protocol: TCP
          port: 6379
    - to:
        - ipBlock:
            cidr: 0.0.0.0/0
            except:
              - 10.0.0.0/8
      ports:
        - protocol: TCP
          port: 443

Service Account & RBAC

# k8s/rbac.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: myapp-sa
  namespace: production
---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: myapp-role
  namespace: production
rules:
  - apiGroups: [""]
    resources: ["configmaps", "secrets"]
    verbs: ["get", "list", "watch"]
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["get", "list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: myapp-rolebinding
  namespace: production
subjects:
  - kind: ServiceAccount
    name: myapp-sa
    namespace: production
roleRef:
  kind: Role
  name: myapp-role
  apiGroup: rbac.authorization.k8s.io

StatefulSet for Stateful Apps

# k8s/statefulset.yaml
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: database
  namespace: production
spec:
  serviceName: database-headless
  replicas: 3
  selector:
    matchLabels:
      app: database
  template:
    metadata:
      labels:
        app: database
    spec:
      containers:
        - name: postgres
          image: postgres:15
          ports:
            - containerPort: 5432
          env:
            - name: POSTGRES_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: db-secrets
                  key: password
          volumeMounts:
            - name: data
              mountPath: /var/lib/postgresql/data
  volumeClaimTemplates:
    - metadata:
        name: data
      spec:
        accessModes: ["ReadWriteOnce"]
        storageClassName: fast-ssd
        resources:
          requests:
            storage: 100Gi

CronJob

# k8s/cronjob.yaml
apiVersion: batch/v1
kind: CronJob
metadata:
  name: backup-job
  namespace: production
spec:
  schedule: "0 2 * * *"
  timeZone: "America/New_York"
  concurrencyPolicy: Forbid
  successfulJobsHistoryLimit: 3
  failedJobsHistoryLimit: 1
  jobTemplate:
    spec:
      backoffLimit: 3
      activeDeadlineSeconds: 3600
      template:
        spec:
          restartPolicy: OnFailure
          containers:
            - name: backup
              image: myregistry/backup:latest
              env:
                - name: S3_BUCKET
                  value: my-backups
              resources:
                requests:
                  cpu: 100m
                  memory: 256Mi
                limits:
                  cpu: 500m
                  memory: 512Mi

Kustomize Structure

# k8s/base/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - deployment.yaml
  - service.yaml
  - configmap.yaml
  - hpa.yaml
  - pdb.yaml

commonLabels:
  app.kubernetes.io/name: myapp
  app.kubernetes.io/managed-by: kustomize

---
# k8s/overlays/production/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

namespace: production

resources:
  - ../../base
  - ingress.yaml
  - network-policy.yaml

replicas:
  - name: app-deployment
    count: 5

images:
  - name: myregistry/myapp
    newTag: v1.2.3

patches:
  - path: deployment-patch.yaml

Best Practices

1. Resource limits: Always set requests and limits
2. Health probes: Configure liveness and readiness
3. Security context: Run as non-root, drop capabilities
4. Pod anti-affinity: Spread across nodes/zones
5. Network policies: Restrict pod communication
6. Secrets management: Use external secrets operator
7. Rolling updates: Configure maxSurge and maxUnavailable
8. PDB: Ensure minimum availability during updates

Output Checklist

Every Kubernetes deployment should include:

• Namespace isolation
• Deployment with resource limits
• Health probes (liveness/readiness)
• Security context (non-root, read-only fs)
• Service for networking
• Ingress with TLS
• ConfigMaps for configuration
• Secrets (preferably external)
• HPA for autoscaling
• PDB for availability
• Network policies
• ServiceAccount with minimal RBAC