Kubernetes Services & Ingress. project #1

PREREQUISITES (ONCE)

minikube start
kubectl get nodes

Expected:

minikube   Ready

---

BASE APP (USED FOR ALL PROJECTS)

One app. Same Pods. Only networking changes.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: demo
  template:
    metadata:
      labels:
        app: demo
    spec:
      containers:
      - name: app
        image: hashicorp/http-echo:0.2.3
        args:
          - "-listen=:8080"
          - "-text=HELLO FROM POD"
        ports:
        - containerPort: 8080

kubectl apply -f deployment.yaml
kubectl get pods

---

PROJECT 1 — ClusterIP (Internal Only)

What This Proves

✔ Services give stable internal networking
✔ Pod IPs change — Service never changes

---

Create ClusterIP

apiVersion: v1
kind: Service
metadata:
  name: demo-clusterip
spec:
  selector:
    app: demo
  ports:
  - port: 80
    targetPort: 8080

kubectl apply -f svc-clusterip.yaml
kubectl get svc

---

Test (Correct Way)

kubectl run test --rm -it --image=busybox -- sh
wget -qO- demo-clusterip

---

PROD ISSUE #1 — No endpoints

kubectl get endpoints demo-clusterip

Cause

• Selector ≠ Pod labels

Fix

kubectl get pods --show-labels
kubectl edit svc demo-clusterip

---

DevOps Takeaway

ClusterIP is the backbone of Kubernetes.
If this fails — nothing works.

---

PROJECT 2 — NodePort (Why It Is Dangerous)

What This Proves

✔ NodePort opens ports
❌ Does NOT provide routing, HA, or stable IP

---

Create NodePort

apiVersion: v1
kind: Service
metadata:
  name: demo-nodeport
spec:
  type: NodePort
  selector:
    app: demo
  ports:
  - port: 80
    targetPort: 8080
    nodePort: 30080

kubectl apply -f svc-nodeport.yaml
kubectl get svc

---

Access

minikube ip
curl http://<MINIKUBE-IP>:30080

---

PROD ISSUE #1 — Random failures

kubectl delete pod -l app=demo

Still works?
YES → kube-proxy reroutes

Now imagine node deleted in cloud → ❌ DEAD

---

PROD ISSUE #2 — Port blocked

In Minikube:
✔ works

In cloud:
❌ security group missing port

---

DevOps Verdict

Use	Verdict
Learning	✅
Debug	✅
Production	❌

---

PROJECT 3 — LoadBalancer (Minikube Style)

What This Proves

✔ Kubernetes requests LB
✔ Minikube simulates cloud LB

---

Create LoadBalancer

apiVersion: v1
kind: Service
metadata:
  name: demo-lb
spec:
  type: LoadBalancer
  selector:
    app: demo
  ports:
  - port: 80
    targetPort: 8080

kubectl apply -f svc-lb.yaml
kubectl get svc

---

VERY IMPORTANT (Minikube Only)

minikube tunnel

Keep terminal open.

Now:

kubectl get svc demo-lb

You will see:

EXTERNAL-IP: 127.0.0.1

curl http://127.0.0.1

---

PROD ISSUE #1 — EXTERNAL-IP pending

Cause

• No tunnel

Fix

minikube tunnel

---

PROD ISSUE #2 — LB exists but no traffic

kubectl describe svc demo-lb
kubectl get endpoints demo-lb

Cause

• Pods not Ready

---

DevOps Verdict

✔ Simple external apps
❌ Expensive in real cloud
❌ One LB per service

---

PROJECT 4 — Ingress (REAL PRODUCTION MODEL)

What This Proves

✔ Ingress is external traffic brain
✔ One IP → many apps

---

STEP 1 — Enable Ingress in Minikube

minikube addons enable ingress
kubectl get pods -n ingress-nginx

Wait until:

ingress-nginx-controller Running

---

STEP 2 — ClusterIP for Ingress

apiVersion: v1
kind: Service
metadata:
  name: demo-ingress-svc
spec:
  selector:
    app: demo
  ports:
  - port: 80
    targetPort: 8080

---

STEP 3 — Ingress Rule

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: demo-ingress
spec:
  rules:
  - host: demo.local
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: demo-ingress-svc
            port:
              number: 80

---

STEP 4 — DNS (Local)

minikube ip
sudo nano /etc/hosts

Add:

<MINIKUBE-IP> demo.local

---

Test

curl http://demo.local

---

PROD ISSUE #1 — 404 from Ingress

kubectl describe ingress demo-ingress

Cause

• Wrong service name
• Wrong port

---

PROD ISSUE #2 — Ingress OK, app broken

kubectl get endpoints demo-ingress-svc
kubectl get pods

Cause

• No Ready pods

---

PROD ISSUE #3 — Ingress controller down

kubectl get pods -n ingress-nginx
kubectl logs -n ingress-nginx <controller-pod>

---

FINAL DEVOPS MENTAL MODEL (MINIKUBE OR PROD)

Client
 |
 v
Ingress (routing rules)
 |
 v
Service (ClusterIP)
 |
 v
Pod

---

FINAL SUMMARY TABLE

Component	Purpose	Who Provides It
ClusterIP	Internal networking	Kubernetes
NodePort	Port exposure	Kubernetes
LoadBalancer	External IP	Cloud / Minikube
Ingress	Routing + TLS	Kubernetes
Egress	Outbound traffic	Cloud / NAT