Kubernetes Fundamentals

Kubernetes orchestrates containers at scale, managing deployment, scaling, and operations of containerized applications.

Core Concepts

Pods

Smallest deployable unit. Contains one or more containers.

Services

Network abstraction providing stable IP and DNS name.

Deployments

Manages replica sets and rolling updates.

Namespaces

Virtual clusters for organizing resources.

Basic Commands

kubectl get pods              # List pods
kubectl get services          # List services
kubectl get deployments       # List deployments
kubectl describe pod name     # Pod details
kubectl logs pod-name         # Pod logs
kubectl exec -it pod-name -- /bin/sh  # Execute in pod

Deployment Example

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

Service Example

apiVersion: v1
kind: Service
metadata:
  name: myapp-service
spec:
  selector:
    app: myapp
  ports:
  - port: 80
    targetPort: 80
  type: LoadBalancer

Apply Configuration

kubectl apply -f deployment.yaml
kubectl apply -f service.yaml
kubectl get all

Scaling

kubectl scale deployment myapp --replicas=5
kubectl autoscale deployment myapp --min=2 --max=10

Updates

kubectl set image deployment/myapp myapp=myapp:v2
kubectl rollout status deployment/myapp
kubectl rollout undo deployment/myapp

ConfigMaps and Secrets

kubectl create configmap myconfig --from-file=config.properties
kubectl create secret generic mysecret --from-literal=key=value

Best Practices

Use declarative configuration
Version control all manifests
Use namespaces for organization
Set resource limits
Implement health checks
Use secrets for sensitive data

Kubernetes is the foundation of modern container orchestration.