Merge pull request #10 from srbdev/kubernetes-updates

Author: scanon

_episodes/32.servics.md

@@ -11,3 +11,153 @@ keypoints:
 - Docker Compose is a simple tool to deploy basic services using containers
 - Frameworks like Kubernetes, Rancher and OpenShift can help with deploying and managing complex containerized services.
 ---
+
+# Container Services and Kubernetes
+
+## First Steps
+
+```bash
+kubectl get nodes
+kubectl get pods
+kubectl get pods -A
+```
+
+## Create a Namespace
+
+```bash
+kubectl create namespace NAME
+```
+
+## Deploy the Application
+
+Create `demo-app.yaml`
+
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: backend-api
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app: backend-api
+  template:
+    metadata:
+      labels:
+        app: backend-api
+    spec:
+      containers:
+      - name: api
+        image: nginx:alpine
+        ports:
+        - containerPort: 80
+        resources:
+          requests:
+            memory: "64Mi"
+            cpu: "100m"
+          limits:
+            memory: "128Mi"
+            cpu: "200m"
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: backend-service
+spec:
+  selector:
+    app: backend-api
+  ports:
+  - port: 80
+    targetPort: 80
+  type: ClusterIP
+---
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: app-ingress
+spec:
+  rules:
+  - host: demo.local
+    http:
+      paths:
+      - path: /
+        pathType: Prefix
+        backend:
+          service:
+            name: backend-service
+            port:
+              number: 80
+```
+
+```bash
+kubectl apply -f demo-app.yaml -n NAME  # OR --namespace=NAME
+kubectl get pods,svc,ingress -n NAME
+```
+
+## Key Kubernetes Features
+
+### Self-Healing
+
+```bash
+# Show running pods
+kubectl get pods -n NAME
+
+# Kill a pod
+kubectl delete pod pod-name-xyz -n NAME
+
+# Watch Kubernetes automatically recreate it
+kubectl get pods -w -n NAME
+```
+
+### Scaling
+
+```bash
+# Scale up during "traffic spike"
+kubectl scale deployment backend-api --replicas=5 -n NAME
+kubectl get pods -n NAME
+
+# Scale down
+kubectl scale deployment backend-api --replicas=2 -n NAME
+```
+
+### Rolling Updates
+
+```bash
+# Update to new version with zero downtime
+kubectl set image deployment/backend-api api=nginx:1.21-alpine -n NAME
+
+# Watch the rolling update
+kubectl rollout status deployment/backend-api -n NAME
+kubectl get pods -n NAME
+
+# Rollback if needed
+kubectl rollout undo deployment/backend-api -n NAME
+```
+
+### Resource Management
+
+```bash
+# Show resource usage
+kubectl top nodes
+kubectl top pods -n NAME
+```
+
+## Port Forwarding
+
+```bash
+curl http://localhost:8000
+
+# Forward local port to the service
+kubectl port-forward svc/backend-service 8000:80 -n NAME
+
+# Access in browser or curl
+curl http://localhost:8000
+# or open http://localhost:8000 in browser
+```
+
+## Clean up Namespaces
+
+```bash
+kubectl delete namespaces NAME
+```