Kubernetes for Beginners: Complete Guide to Container Orchestration

Kubernetes (K8s) is the industry-standard container orchestration platform. This guide covers everything you need to get started with Kubernetes.

Core Kubernetes Concepts

1. Pods - The Smallest Deployable Unit

# pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: my-app-pod
  labels:
    app: my-app
spec:
  containers:
    - name: my-app
      image: nginx:latest
      ports:
        - containerPort: 80
      resources:
        limits:
          memory: "128Mi"
          cpu: "500m"
        requests:
          memory: "64Mi"
          cpu: "250m"

# Create pod
kubectl apply -f pod.yaml

# View pods
kubectl get pods

# Describe pod details
kubectl describe pod my-app-pod

# View logs
kubectl logs my-app-pod

2. Deployments - Managing Replicas

# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-app
          image: my-app:v1.0.0
          ports:
            - containerPort: 8080
          env:
            - name: DATABASE_URL
              valueFrom:
                secretKeyRef:
                  name: db-secret
                  key: url
          livenessProbe:
            httpGet:
              path: /health
              port: 8080
            initialDelaySeconds: 30
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /ready
              port: 8080
            initialDelaySeconds: 5
            periodSeconds: 5

3. Services - Exposing Applications

# service.yaml
apiVersion: v1
kind: Service
metadata:
  name: my-app-service
spec:
  selector:
    app: my-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
  type: LoadBalancer  # or ClusterIP, NodePort

4. ConfigMaps and Secrets

# configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  APP_ENV: production
  LOG_LEVEL: info
  MAX_CONNECTIONS: "100"

---
# secret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: db-secret
type: Opaque
data:
  password: cGFzc3dvcmQxMjM=  # base64 encoded
  url: cG9zdGdyZXM6Ly9sb2NhbGhvc3Q6NTQzMg==

5. Ingress - External Access

# ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-app-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx
  rules:
    - host: myapp.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: my-app-service
                port:
                  number: 80

Essential kubectl Commands

# Cluster info
kubectl cluster-info
kubectl get nodes

# Deployments
kubectl get deployments
kubectl rollout status deployment/my-app
kubectl rollout history deployment/my-app
kubectl rollout undo deployment/my-app

# Scaling
kubectl scale deployment my-app --replicas=5

# Debugging
kubectl exec -it pod-name -- /bin/sh
kubectl port-forward pod-name 8080:80
kubectl top pods
kubectl top nodes

# Apply configurations
kubectl apply -f kubernetes/
kubectl delete -f kubernetes/

Helm Charts for Package Management

# Install Helm
curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

# Add repository
helm repo add bitnami https://charts.bitnami.com/bitnami

# Install application
helm install my-release bitnami/postgresql

# Create your own chart
helm create my-chart
helm package my-chart
helm install my-release ./my-chart

Kubernetes mastery opens doors to cloud-native development. Start with these fundamentals and gradually explore advanced topics!