3. Deploying Applications on Your K3s Cluster - Practical Examples

Once your K3s cluster is up and running, the next step is deploying applications. Whether you're experimenting with Kubernetes for the first time or testing production-ready workloads locally, K3s makes it simple and efficient. In this blog, we’ll walk through deploying a web application, adding a database service, and managing apps using Helm. By the end, you’ll have a solid understanding of deploying and monitoring applications on your K3s cluster.

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Preparing Your Environment

Before we dive into deploying applications, let’s ensure your environment is ready:

Prerequisites

1. A functioning K3s cluster. (If you haven’t set one up yet, check out our guide on Getting Started with K3s.)

2. kubectl installed and configured to communicate with your cluster.

3. Basic familiarity with Kubernetes concepts (pods, deployments, services).

4. Optional: Install Helm (we’ll cover this later).

To verify your setup, run:

kubectl get nodes

You should see your K3s node(s) listed with a STATUS of Ready.

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Example Deployments

Let’s start with a simple example: deploying a web application and a database service alongside it.

Deploying a Web Application

We’ll deploy a basic NGINX-based web app using a YAML manifest.

1. Create a file named web-app.yaml:

apiVersion: apps/v1  
kind: Deployment  
metadata:  
  name: web-app  
  labels:  
    app: web-app  
spec:  
  replicas: 2  
  selector:  
    matchLabels:  
      app: web-app  
  template:  
    metadata:  
      labels:  
        app: web-app  
    spec:  
      containers:  
      - name: nginx  
        image: nginx:latest  
        ports:  
        - containerPort: 80  
---  
apiVersion: v1  
kind: Service  
metadata:  
  name: web-app-service  
spec:  
  selector:  
    app: web-app  
  ports:  
  - protocol: TCP  
    port: 80  
    targetPort: 80  
  type: LoadBalancer

2. Apply the manifest:

kubectl apply -f web-app.yaml

3. Verify the deployment:

kubectl get pods

You should see two pods running for the web-app deployment.

4. Access the app:
   Find the external IP or port assigned to the web-app-service using:

kubectl get svc web-app-service

Access the web app in your browser or via curl.

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Adding a Database Service

Now, let’s add a database service (e.g., MySQL) to work alongside the web app.

1. Create a file named mysql.yaml:

apiVersion: v1  
kind: PersistentVolumeClaim  
metadata:  
  name: mysql-pvc  
spec:  
  accessModes:  
    - ReadWriteOnce  
  resources:  
    requests:  
      storage: 1Gi  
---  
apiVersion: apps/v1  
kind: Deployment  
metadata:  
  name: mysql  
  labels:  
    app: mysql  
spec:  
  replicas: 1  
  selector:  
    matchLabels:  
      app: mysql  
  template:  
    metadata:  
      labels:  
        app: mysql  
    spec:  
      containers:  
      - name: mysql  
        image: mysql:5.7  
        env:  
        - name: MYSQL_ROOT_PASSWORD  
          value: rootpassword  
        ports:  
        - containerPort: 3306  
        volumeMounts:  
        - mountPath: /var/lib/mysql  
          name: mysql-storage  
      volumes:  
      - name: mysql-storage  
        persistentVolumeClaim:  
          claimName: mysql-pvc  
---  
apiVersion: v1  
kind: Service  
metadata:  
  name: mysql  
spec:  
  ports:  
  - port: 3306  
  selector:  
    app: mysql  
  type: ClusterIP

2. Apply the manifest:

kubectl apply -f mysql.yaml

3. Verify the deployment:

kubectl get pods

Ensure the MySQL pod is running and its STATUS is Running.

Now your web app can connect to the MySQL service using the service name mysql and port 3306.

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Using Helm Charts

K3s is fully compatible with Helm, a powerful Kubernetes package manager. Helm simplifies deploying and managing complex applications with reusable templates.

Installing Helm

1. Download Helm:

curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

2. Verify installation:

helm version

Deploying Applications with Helm

Let’s use Helm to deploy WordPress (a web app + database combo).

1. Add the Helm repo:

helm repo add bitnami https://charts.bitnami.com/bitnami  
helm repo update

2. Install WordPress:

helm install my-wordpress bitnami/wordpress

3. Check the status:

helm status my-wordpress

4. Access the application:
   Get the external IP of the WordPress service:

kubectl get svc

Visit the IP in your browser to see your WordPress site in action.

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Monitoring and Managing Applications

Monitoring your applications is critical, even in a local environment. Here are a few tools and techniques for managing your K3s workloads:

Using kubectl for Basic Monitoring

• Check pod status:

    kubectl get pods
  

• View pod logs:

    kubectl logs <pod-name>
  

Adding Metrics with Prometheus and Grafana

1. Deploy Prometheus and Grafana using Helm:

helm install prometheus bitnami/kube-prometheus
helm install grafana bitnami/grafana

2. Access the Grafana dashboard and connect it to Prometheus as a data source for visualizing metrics.

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Conclusion

Deploying applications on K3s is not only straightforward but also versatile enough to handle a wide range of use cases. Whether you’re deploying simple web apps, integrating databases, or managing complex workloads with Helm, K3s provides the tools and simplicity to get the job done.

What’s Next?

• Experiment with scaling your applications and using K3s in multi-node setups.

• Explore CI/CD pipelines for automating application deployments on your K3s cluster.

• Dive deeper into monitoring tools like Prometheus, Grafana, and Loki for a robust observability stack.

Have questions or cool deployment ideas? Let us know in the comments below!