Kubernetes

Kubernetes

Production-ready Kubernetes manifest generation covering Deployments, StatefulSets, CronJobs, Services, Ingresses, ConfigMaps, Secrets, and PVCs with security contexts, health checks, and resource management.

Installation

OpenClaw / Moltbot / Clawbot

npx clawhub@latest install kubernetes-devops

When to Use

Scenario	Example
Create deployment manifests	New microservice needing Deployment + Service
Define networking resources	ClusterIP, LoadBalancer, Ingress with TLS
Manage configuration	ConfigMaps for app config, Secrets for credentials
Stateful workloads	Databases with StatefulSets + PVCs
Scheduled jobs	CronJobs for batch processing
Multi-environment setup	Kustomize overlays for dev/staging/prod

Workload Selection

Workload Type	Resource	When to Use
Stateless app	Deployment	Web servers, APIs, microservices
Stateful app	StatefulSet	Databases, message queues, caches
One-off task	Job	Migrations, data imports
Scheduled task	CronJob	Backups, reports, cleanup
Per-node agent	DaemonSet	Log collectors, monitoring agents

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
  namespace: production
  labels:
    app.kubernetes.io/name: my-app
    app.kubernetes.io/version: "1.0.0"
    app.kubernetes.io/component: backend
spec:
  replicas: 3
  selector:
    matchLabels:
      app.kubernetes.io/name: my-app
  template:
    metadata:
      labels:
        app.kubernetes.io/name: my-app
        app.kubernetes.io/version: "1.0.0"
    spec:
      securityContext:
        runAsNonRoot: true
        runAsUser: 1000
        fsGroup: 1000
        seccompProfile:
          type: RuntimeDefault
      containers:
        - name: my-app
          image: registry.example.com/my-app:1.0.0
          ports:
            - containerPort: 8080
              name: http
          resources:
            requests:
              cpu: 250m
              memory: 256Mi
            limits:
              cpu: 500m
              memory: 512Mi
          securityContext:
            allowPrivilegeEscalation: false
            readOnlyRootFilesystem: true
            capabilities:
              drop: [ALL]
          livenessProbe:
            httpGet:
              path: /health
              port: http
            initialDelaySeconds: 30
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /ready
              port: http
            initialDelaySeconds: 5
            periodSeconds: 5
          env:
            - name: LOG_LEVEL
              valueFrom:
                configMapKeyRef:
                  name: my-app-config
                  key: LOG_LEVEL
            - name: DB_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: my-app-secret
                  key: DATABASE_PASSWORD

Services

ClusterIP (Internal)

apiVersion: v1
kind: Service
metadata:
  name: my-app
  namespace: production
spec:
  type: ClusterIP
  selector:
    app.kubernetes.io/name: my-app
  ports:
    - name: http
      port: 80
      targetPort: 8080
      protocol: TCP

LoadBalancer (External)

apiVersion: v1
kind: Service
metadata:
  name: my-app-lb
  namespace: production
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-type: nlb
spec:
  type: LoadBalancer
  selector:
    app.kubernetes.io/name: my-app
  ports:
    - name: http
      port: 80
      targetPort: 8080

Service Type Quick Reference

Type	Scope	Use Case
ClusterIP	Cluster-internal	Inter-service communication
NodePort	External via node IP	Dev/testing, on-prem
LoadBalancer	External via cloud LB	Production external access
ExternalName	DNS alias	Mapping to external services

Ingress

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-app
  namespace: production
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/rate-limit: "100"
spec:
  ingressClassName: nginx
  tls:
    - hosts: [app.example.com]
      secretName: app-tls
  rules:
    - host: app.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: my-app
                port:
                  number: 80

ConfigMap & Secret

ConfigMap

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-app-config
  namespace: production
data:
  LOG_LEVEL: info
  APP_MODE: production
  DATABASE_HOST: db.internal.svc.cluster.local
  app.properties: |
    server.port=8080
    server.host=0.0.0.0

Secret

apiVersion: v1
kind: Secret
metadata:
  name: my-app-secret
  namespace: production
type: Opaque
stringData:
  DATABASE_PASSWORD: "changeme"
  API_KEY: "secret-api-key"

Important: Never commit plaintext Secrets to Git. Use Sealed Secrets, External Secrets Operator, or Vault for production.

Persistent Storage

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-app-data
  namespace: production
spec:
  accessModes: [ReadWriteOnce]
  storageClassName: gp3
  resources:
    requests:
      storage: 10Gi

Mount in a container:

containers:
  - name: app
    volumeMounts:
      - name: data
        mountPath: /var/lib/app
volumes:
  - name: data
    persistentVolumeClaim:
      claimName: my-app-data

Access Mode	Abbreviation	Use Case
ReadWriteOnce	RWO	Single-pod databases
ReadOnlyMany	ROX	Shared config/static assets
ReadWriteMany	RWX	Multi-pod shared storage

Security Context

Pod-Level

spec:
  securityContext:
    runAsNonRoot: true
    runAsUser: 1000
    fsGroup: 1000
    seccompProfile:
      type: RuntimeDefault

Container-Level

securityContext:
  allowPrivilegeEscalation: false
  readOnlyRootFilesystem: true
  capabilities:
    drop: [ALL]

Security Checklist

Check	Status
runAsNonRoot: true	Required
allowPrivilegeEscalation: false	Required
readOnlyRootFilesystem: true	Recommended
capabilities.drop: [ALL]	Required
seccompProfile: RuntimeDefault	Recommended
Specific image tags (never :latest)	Required
Resource requests and limits set	Required

Standard Labels

metadata:
  labels:
    app.kubernetes.io/name: my-app
    app.kubernetes.io/instance: my-app-prod
    app.kubernetes.io/version: "1.0.0"
    app.kubernetes.io/component: backend
    app.kubernetes.io/part-of: my-system
    app.kubernetes.io/managed-by: kubectl

Manifest Organization

Option 1 — Separate Files

manifests/
├── configmap.yaml
├── secret.yaml
├── deployment.yaml
├── service.yaml
└── pvc.yaml

Option 2 — Kustomize

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

Validation

# Client-side dry run
kubectl apply -f manifest.yaml --dry-run=client

# Server-side validation
kubectl apply -f manifest.yaml --dry-run=server

# Lint with kube-score
kube-score score manifest.yaml

# Lint with kube-linter
kube-linter lint manifest.yaml

Troubleshooting Quick Reference

Problem	Diagnosis	Fix
Pod stuck Pending	kubectl describe pod — check events	Fix resource requests, node capacity, PVC binding
ImagePullBackOff	Wrong image name/tag or missing pull secret	Verify image exists, add imagePullSecrets
CrashLoopBackOff	App crashes on start	Check logs: kubectl logs <pod> --previous
Service not reachable	Selector mismatch	Verify kubectl get endpoints <svc> is non-empty
ConfigMap not loading	Name mismatch or wrong namespace	Check names match and namespace is correct
Readiness probe failing	Wrong path or port	Verify health endpoint works inside container
OOMKilled	Memory limit too low	Increase resources.limits.memory

NEVER Do

Anti-Pattern	Why	Do Instead
Use :latest image tag	Non-reproducible deployments	Pin exact version: image:1.2.3
Skip resource limits	Pods can starve the node	Always set requests and limits
Run as root	Container escape = full host access	Set runAsNonRoot: true + USER
Commit plaintext Secrets	Credentials in Git history forever	Use Sealed Secrets / External Secrets / Vault
Skip health checks	K8s can't detect unhealthy pods	Always configure liveness + readiness probes
Omit labels	Cannot filter, select, or organize	Use standard app.kubernetes.io/* labels
Single replica for production	Zero availability during updates	Use replicas: 3 minimum for HA
Hardcode config in containers	Requires rebuild for config changes	Use ConfigMaps and Secrets

Assets & References

Assets (Templates)

Template	Description
assets/deployment-template.yaml	Production Deployment with security + probes
assets/service-template.yaml	ClusterIP, LoadBalancer, NodePort examples
assets/configmap-template.yaml	ConfigMap with data types
assets/statefulset-template.yaml	StatefulSet with headless Service + PVC
assets/cronjob-template.yaml	CronJob with concurrency + history
assets/ingress-template.yaml	Ingress with TLS, rate limiting, CORS

References

Reference	Description
references/deployment-spec.md	Detailed Deployment specification
references/service-spec.md	Service types and networking details