<h2>What is Kubernetes?</h2>
<p>Kubernetes (K8s) is an open-source container orchestration platform that automates deployment, scaling, and management of containerized applications. Originally developed by Google, it's now the industry standard for running containers at scale.</p>
<h2>Why Use Kubernetes?</h2>
<ul>
<li><strong>Auto-scaling:</strong> Automatically scale applications based on demand</li>
<li><strong>Self-healing:</strong> Restart failed containers, replace unhealthy nodes</li>
<li><strong>Load balancing:</strong> Distribute network traffic across containers</li>
<li><strong>Rolling updates:</strong> Deploy updates with zero downtime</li>
<li><strong>Service discovery:</strong> Containers find each other automatically</li>
</ul>
<h2>Core Concepts</h2>
<h3>Pod</h3>
<p>The smallest deployable unit in Kubernetes. A pod contains one or more containers that share storage and network.</p>
<pre><code>apiVersion: v1
kind: Pod
metadata:
name: my-app
spec:
containers:
- name: app
image: nginx:latest
ports:
- containerPort: 80</code></pre>
<h3>Deployment</h3>
<p>Manages a set of replica pods, ensuring the desired number always runs:</p>
<pre><code>apiVersion: apps/v1
kind: Deployment
metadata:
name: my-app
spec:
replicas: 3
selector:
matchLabels:
app: my-app
template:
metadata:
labels:
app: my-app
spec:
containers:
- name: app
image: nginx:latest
ports:
- containerPort: 80</code></pre>
<h3>Service</h3>
<p>Exposes your application and provides stable networking:</p>
<pre><code>apiVersion: v1
kind: Service
metadata:
name: my-app-service
spec:
selector:
app: my-app
ports:
- port: 80
targetPort: 80
type: LoadBalancer</code></pre>
<h2>Setting Up a Local Cluster</h2>
<p>Use <strong>minikube</strong> for local development:</p>
<pre><code># Install minikube
curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64
sudo install minikube-linux-amd64 /usr/local/bin/minikube
# Start cluster
minikube start
# Verify
kubectl get nodes</code></pre>
<h2>Deploying Your First App</h2>
<pre><code># Create deployment
kubectl create deployment hello-world --image=gcr.io/google-samples/hello-app:1.0
# Expose it
kubectl expose deployment hello-world --type=LoadBalancer --port=8080
# Check status
kubectl get pods
kubectl get services</code></pre>
<h2>Useful kubectl Commands</h2>
<ul>
<li><code>kubectl get pods</code> — List all pods</li>
<li><code>kubectl describe pod [name]</code> — Details about a pod</li>
<li><code>kubectl logs [pod-name]</code> — View pod logs</li>
<li><code>kubectl exec -it [pod] -- bash</code> — Shell into a pod</li>
<li><code>kubectl apply -f manifest.yaml</code> — Apply a configuration</li>
<li><code>kubectl delete -f manifest.yaml</code> — Delete resources</li>
</ul>
<h2>Conclusion</h2>
<p>Kubernetes has a steep learning curve, but it's the foundation of modern cloud-native development. Start with minikube locally, master the basics, then explore managed services like GKE, EKS, or AKS for production workloads.</p>