Important Notes on Kubernetes

Important Notes on Kubernetes

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Why can't I access minikube ip from my local machine directly?

• Minikube runs in a Docker container, not a full VM.

• This container is on a Docker network bridge, which is not directly exposed to your host.

• The IP from minikube ip is internal to Docker, and your host can’t route to it directly.

• Use this instead:

  minikube service <svc-name>
  

  This command creates a temporary tunnel to expose the service on your local machine.

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How to access the terminal for a pod?

kubectl exec -it <pod-name> -- sh

Replace <pod-name> with your actual pod name.

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Can one pod ping or curl another pod?

Yes! Pods in the same Kubernetes cluster can freely communicate with each other.

How Pod Communication Works:

• Each pod gets a unique IP (e.g., 10.244.0.x)
• Any pod can talk to any other pod directly via its IP.
• No need for:
  • Port forwarding
  • NodePort
  • Ingress (between pods)
• Kubernetes provides built-in DNS-based service discovery.

Option 1: Use Pod IP

kubectl get pods -o wide
curl http://10.244.0.54:5000

Option 2 (Recommended): Use Kubernetes Service Name

curl http://spring-boot-app:5000

This works because Kubernetes sets up DNS entries for services.

• Same namespace: use spring-boot-app
• Different namespace: use

  spring-boot-app.<namespace>.svc.cluster.local
  

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What does kubectl run do?

• Creates a single pod
• Great for on-the-fly debugging
• Acts like a Kubernetes-native alternative to docker run

kubectl run -it --rm debug --image=busybox -- sh

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1. YAML for a Standalone Pod (No Deployment)

apiVersion: v1
kind: Pod
metadata:
  name: easy-recipes-pod
spec:
  containers:
    - name: easy-recipes-container
      image: ram1uj/easy-recipes
      ports:
        - containerPort: 80

Apply with:

kubectl apply -f easy-recipes-pod.yaml

Runs a single pod with no auto-restart or scaling.

---

2. Deployment YAML (Recommended for Production)

apiVersion: apps/v1
kind: Deployment
metadata:
  name: easy-recipes
spec:
  replicas: 2
  selector:
    matchLabels:
      app: easy-recipes
  template:
    metadata:
      labels:
        app: easy-recipes
    spec:
      containers:
        - name: easy-recipes
          image: ram1uj/easy-recipes
          ports:
            - containerPort: 80

Apply with:

kubectl apply -f easy-recipes-deployment.yaml

This gives you:

• Multiple replicas
• Auto-recovery on crash
• Rolling updates

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Service YAML Example

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: myapp
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
  type: NodePort

This exposes your pod to the outside world using a NodePort.