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Kubernetes

Kubernetes (K8s)

1. Kubernetes Basics

Display cluster information
kubectl cluster-info`
List all nodes in the cluster
kubectl get nodes`
List all pods in the current namespace
kubectl get pods`
List all services
kubectl get services`
List all deployments
kubectl get deployments`

2. Managing Pods

Create a pod with Nginx
kubectl run my-pod` --image=nginx
Delete a pod
kubectl delete pod my-pod`
View pod logs
kubectl logs my-pod`
Access a pod's shell
kubectl exec -it my-pod -- /bin/sh`

3. Managing Deployments

Create a deployment
kubectl create deployment my-deploy --image=nginx`
Scale deployment to 3 replicas
kubectl scale deployment my-deploy --replicas=3`
Check rollout status
kubectl rollout status deployment my-deploy`
Rollback to the previous version
kubectl rollout undo deployment my-deploy`

4. Managing Services

Expose deployment as a service
kubectl expose deployment my-deploy --type=NodePort --port=80`
List services
kubectl get svc`
Get service details
kubectl describe svc my-service`

5. Namespaces

List all namespaces
kubectl get ns`
Create a new namespace
kubectl create namespace dev`
Delete a namespace
kubectl delete namespace dev`

6. ConfigMaps & Secrets

Create a ConfigMap
kubectl create configmap my-config --from-literal=key=value`
List ConfigMaps
kubectl get configmap`
Create a secret
kubectl create secret generic my-secret --from-literal=password=12345`
List secrets
kubectl get secrets`

7. Troubleshooting

View cluster events
kubectl get events
Get detailed pod information
kubectl describe pod my-pod
View logs of a specific pod
kubectl logs my-pod
Show resource usage of pods
kubectl top pod

8. Helm (Package Manager for Kubernetes)

Add a Helm repo
helm repo add stable https://charts.helm.sh/stable
Install a Helm chart
helm install my-release stable/nginx
List installed releases
helm list
Uninstall a release
helm delete my-release

9. Persistent Volumes & Storage

List persistent volume claims
kubectl get pvc
List persistent volumes
kubectl get pv
Describe a persistent volume claim
kubectl describe pvc <pvc>
Delete a persistent volume claim
kubectl delete pvc <pvc>

10. Autoscaling

Enable autoscaling
kubectl autoscale deployment <deployment> --cpu-percent=50 --min=1 --max=10
View horizontal pod autoscaler
kubectl get hpa

11. Kubernetes Debugging

Show events
kubectl get events --sort-by=.metadata.creationTimestamp
Show pod details
kubectl describe pod <pod>
Check logs
kubectl logs <pod>
Access pod shell
kubectl exec -it <pod> -- /bin/sh

Kubernetes YAML Configurations

1. Pod

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: nginx
  image: nginx:latest
  ports:
  - containerPort: 80

2. Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 3
  selector:
  matchLabels:
    app: my-app
  template:
  metadata:
    labels:
      app: my-app
    spec:
      containers:
      - name: nginx
      image: nginx:latest
      ports:
        - containerPort: 80

3. ReplicaSet

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: my-replicaset
spec:
  replicas: 3
  selector:
  matchLabels:
    app: my-app
  template:
  metadata:
    labels:
    app: my-app
  spec:
    containers:
      - name: nginx
      image: nginx:latest

4. Service (ClusterIP, NodePort, LoadBalancer)

  • ClusterIP (default)
apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: my-app
  ports:
  - protocol: TCP
  port: 80
  targetPort: 80
  • NodePort
apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: my-app
  type: NodePort
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
    nodePort: 30080
  • LoadBalancer
apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: my-app
  type: LoadBalancer
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80

5. ConfigMap

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config
data:
  key1: value1
  key2: value2

6. Secret

apiVersion: v1
kind: Secret
metadata:
  name: my-secret
type: Opaque
  data:
    password: cGFzc3dvcmQ= # Base64 encoded value

7. Persistent Volume (PV)

apiVersion: v1
kind: PersistentVolume
metadata:
  name: my-pv
spec:
  capacity:
    storage: 1Gi
  accessModes:
  - ReadWriteOnce
  hostPath:
    path: /mnt/data

8. Persistent Volume Claim (PVC)

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 500Mi

9. Ingress

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-ingress
spec:
  rules:
  - host: example.com
  http:
    paths:
    - path: /
      pathType: Prefix
      backend:
        service:
          name: my-service
          port:
            number: 80

10. Horizontal Pod Autoscaler (HPA)

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: my-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: my-deployment
  minReplicas: 2
  maxReplicas: 5
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 50

11. CronJob

apiVersion: batch/v1
kind: CronJob
metadata:
  name: my-cronjob
spec:
  schedule: "*/5 * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: my-cron
            image: busybox
            command: ["echo", "Hello from CronJob"]
          restartPolicy: OnFailure