Kubernetes Pod Lifecycle: Pending → Running → Succeeded

apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
spec:
  initContainers:
  # Init container 1: Wait for database
  - name: check-database
    image: busybox:1.35
    command: ['sh', '-c']
    args:
    - |
      until nc -z postgres-service 5432; do
        echo "Waiting for database..."
        sleep 2
      done
      echo "Database is ready!"      

  # Init container 2: Setup configuration
  - name: setup-config
    image: busybox:1.35
    command: ['sh', '-c']
    args:
    - |
      cp /config-template/app.conf /config/
      chmod 600 /config/app.conf      
    volumeMounts:
    - name: config
      mountPath: /config
    - name: config-template
      mountPath: /config-template

  # Init container 3: Run migrations
  - name: run-migrations
    image: myapp:v1.0
    command: ['./migrate']
    env:
    - name: DATABASE_URL
      valueFrom:
        secretKeyRef:
          name: db-secret
          key: url

  # Main application container
  containers:
  - name: myapp
    image: myapp:v1.0
    ports:
    - containerPort: 8080
    volumeMounts:
    - name: config
      mountPath: /config

  volumes:
  - name: config
    emptyDir: {}
  - name: config-template
    configMap:
      name: app-config

# Always restart - for services
apiVersion: v1
kind: Pod
metadata:
  name: web-server
spec:
  restartPolicy: Always  # Default
  containers:
  - name: nginx
    image: nginx:1.21

---
# Restart on failure - for batch jobs
apiVersion: v1
kind: Pod
metadata:
  name: data-processor
spec:
  restartPolicy: OnFailure
  containers:
  - name: processor
    image: data-processor:v1

---
# Never restart - for one-time tasks
apiVersion: v1
kind: Pod
metadata:
  name: migration
spec:
  restartPolicy: Never
  containers:
  - name: migrate
    image: migrate:v1

apiVersion: v1
kind: Pod
metadata:
  name: app-with-probes
spec:
  containers:
  - name: app
    image: myapp:v1.0
    ports:
    - containerPort: 8080

    # Startup probe - runs first, protects slow-starting apps
    startupProbe:
      httpGet:
        path: /healthz
        port: 8080
      initialDelaySeconds: 0
      periodSeconds: 5
      failureThreshold: 30  # 30 * 5 = 150 seconds to start

    # Liveness probe - restarts container if fails
    livenessProbe:
      httpGet:
        path: /healthz
        port: 8080
      initialDelaySeconds: 10
      periodSeconds: 10
      failureThreshold: 3
      successThreshold: 1
      timeoutSeconds: 5

    # Readiness probe - controls traffic routing
    readinessProbe:
      httpGet:
        path: /ready
        port: 8080
      initialDelaySeconds: 5
      periodSeconds: 5
      failureThreshold: 3
      successThreshold: 1
      timeoutSeconds: 3

    # Example TCP probe
    # livenessProbe:
    #   tcpSocket:
    #     port: 8080
    #   periodSeconds: 10

    # Example exec probe
    # livenessProbe:
    #   exec:
    #     command:
    #     - cat
    #     - /tmp/healthy
    #   periodSeconds: 10

apiVersion: v1
kind: Pod
metadata:
  name: graceful-shutdown
spec:
  terminationGracePeriodSeconds: 60  # Wait up to 60s
  containers:
  - name: app
    image: myapp:v1.0
    ports:
    - containerPort: 8080

    lifecycle:
      # Called before SIGTERM
      preStop:
        exec:
          command: ["/bin/sh", "-c"]
          args:
          - |
            # Notify application to stop accepting new requests
            curl -X POST http://localhost:8080/shutdown
            # Wait for in-flight requests to complete
            sleep 15            

# Get pod status
kubectl get pods
kubectl get pods -o wide  # Show node and IP

# Detailed pod information
kubectl describe pod <pod-name>

# View pod logs
kubectl logs <pod-name>
kubectl logs <pod-name> -c <container-name>  # Multi-container pod
kubectl logs <pod-name> --previous  # Previous container instance
kubectl logs <pod-name> --follow  # Stream logs

# Execute commands in pod
kubectl exec <pod-name> -- <command>
kubectl exec -it <pod-name> -- /bin/sh  # Interactive shell

# Check pod events
kubectl get events --sort-by=.metadata.creationTimestamp

# View pod YAML
kubectl get pod <pod-name> -o yaml

# Check resource usage
kubectl top pod <pod-name>

# Port forwarding for local access
kubectl port-forward <pod-name> 8080:80

resources:
  requests:
    memory: "256Mi"
    cpu: "250m"
  limits:
    memory: "512Mi"
    cpu: "500m"

startupProbe:   # For slow-starting apps
  httpGet:
    path: /healthz
    port: 8080
  failureThreshold: 30
  periodSeconds: 10

livenessProbe:  # Restart if unhealthy
  httpGet:
    path: /healthz
    port: 8080
  periodSeconds: 10

readinessProbe: # Control traffic routing
  httpGet:
    path: /ready
    port: 8080
  periodSeconds: 5

terminationGracePeriodSeconds: 60
lifecycle:
  preStop:
    exec:
      command: ["/bin/sh", "-c", "sleep 15"]

securityContext:
  runAsNonRoot: true
  runAsUser: 1000
  readOnlyRootFilesystem: true
  capabilities:
    drop:
    - ALL