Deploying a Simple App

Welcome! In this lesson, you'll take a big step: deploying your very first application to your Minikube cluster.

We'll use a powerful command-line tool called kubectl to manage your app's journey from code to a running service.

In Kubernetes, a Deployment is how you tell the cluster to run your application.

• It manages a set of identical application copies (Pods).
• It ensures a specified number of these copies are always running.
• Think of it as the blueprint and manager for your app's instances.

The easiest way to get an app running is with the kubectl create deployment command.

You just need to give your deployment a name and specify the container image you want to run. Kubernetes handles the rest!

Let's deploy a simple Nginx web server. This command tells Kubernetes to create a Deployment named nginx-deployment using the nginx Docker image.

kubectl create deployment nginx-deployment --image=nginx

Run this command in your terminal where Minikube is running.

After running the command, Kubernetes starts creating the necessary resources. You can check their status:

• To see your Deployment: kubectl get deployments
• To see the Pods created by the Deployment: kubectl get pods

Look for your nginx-deployment and its corresponding Pods!

Your Nginx Pod is running, but how do users access it?

• Pods have temporary IP addresses.
• Pods can die and be replaced, getting new IPs.
• A Service provides a stable network endpoint, acting as a gateway to your Pods.

It ensures traffic always reaches a healthy Pod, even if Pods come and go.

To make your Nginx accessible, we'll create a Service using kubectl expose. We'll specify the deployment name and the port.

kubectl expose deployment nginx-deployment --type=NodePort --port=80

This creates a Service that routes external traffic to port 80 of your Nginx Pods.

Now that your Nginx Deployment is exposed by a Service, Minikube can help you access it.

Run the following command, and Minikube will open a browser window to your Nginx web server!

minikube service nginx-deployment

You should see the "Welcome to nginx!" page.

It's good practice to clean up resources you no longer need. This frees up resources in your Minikube cluster.

• To delete the Service: kubectl delete service nginx-deployment
• To delete the Deployment (which also removes its Pods): kubectl delete deployment nginx-deployment

Always delete the Service first, then the Deployment.

You've successfully deployed and exposed an application! Which sequence of kubectl commands would you use to first deploy an app named my-app using the busybox image, and then expose it as a NodePort service on port 8080?

Congratulations! You've successfully deployed, exposed, and accessed your first application on Kubernetes using Minikube.

• We used kubectl create deployment to run our container.
• We used kubectl expose deployment to make it accessible via a Service.
• We accessed it with minikube service and cleaned up with kubectl delete.

You're now one step closer to mastering Kubernetes!