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Introduction
Preparing Your Raspberry Pi Cluster
Installing K3s
Using Your K3s Cluster
Real-World Deployments
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Final Project
Summary

Deploying Apps

Learn how to deploy real-world applications on your K3s cluster using Deployments, Services, and Ingress.

By Kevin McAleer,    3 Minutes

Page last updated May 24, 2025

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Now that your K3s cluster is running and accessible via services and ingress, it’s time to deploy a real-world application.

In this lesson, you’ll deploy a simple web app with a backing Redis database using Deployments, Services, and an Ingress rule.

🧩 Example App: Python + Redis

We’ll deploy:

  • A Flask web app (web)
  • A Redis database (redis)

These will be connected using environment variables and services.

📁 Step 1: Create Deployment YAML

Create a file called webapp.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  replicas: 1
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: web
        image: kevdev/web-redis-demo:latest
        ports:
        - containerPort: 5000
        env:
        - name: REDIS_HOST
          value: redis
---
apiVersion: v1
kind: Service
metadata:
  name: web
spec:
  selector:
    app: web
  ports:
  - protocol: TCP
    port: 80
    targetPort: 5000

This assumes you have a Docker image like kevdev/web-redis-demo on Docker Hub — update it with your own image if needed.

🧱 Step 2: Add Redis Deployment

Append this to the same file or create a separate redis.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
      - name: redis
        image: redis:alpine
---
apiVersion: v1
kind: Service
metadata:
  name: redis
spec:
  selector:
    app: redis
  ports:
  - protocol: TCP
    port: 6379

🚀 Step 3: Apply to the Cluster

kubectl apply -f webapp.yaml
kubectl apply -f redis.yaml

Verify everything is running:

kubectl get pods
kubectl get svc

🌐 Step 4: Add Ingress

Create a file called webapp-ingress.yaml:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: web-ingress
  annotations:
    traefik.ingress.kubernetes.io/router.entrypoints: web
spec:
  rules:
  - host: web.local
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: web
            port:
              number: 80

Apply it:

kubectl apply -f webapp-ingress.yaml

Add this to /etc/hosts on your local machine:

192.168.1.100 web.local

Visit http://web.local in your browser!

🧪 Optional: Scale Your App

kubectl scale deployment web --replicas=3

See the load balancing in action (especially with Ingress).

✅ Summary

You now know how to:

  • Deploy multi-container apps using YAML
  • Connect services via internal DNS
  • Expose apps using Ingress
  • Scale deployments with one command

Next up: Using Helm

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