Kubernetes gives you the ability to deploy your app in a highly available way, and it has provisioning features that you can use to avoid manual tasks.
There are tons of tutorials about Kubernetes out there, but in this simple post, I just want to give you the simplest deployment ever in Kubernetes. You will see how to deploy nginx with Kubernetes and access it easily.
Before deployment, make sure you have properly installed kubectl and minikube, and remove any old stuff from minikube using the delete and start commands.
minikube delete
minikube start
If it works, so everything is fine. lets go ahead. The main part is the deployment.yaml file. write it in a file and apply it.
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
spec:
selector:
matchLabels:
app: nginx
replicas: 2
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:latest
ports:
- containerPort: 80
and then apply it with:
kubectl apply -f deployment.yaml
Now if you check the deployments:
kubectl get deployments
You should see sth like this:
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 2/2 2 2 29s
As you can see, there is an Nginx deployment with 2 replicas. In order to verify if it is actually working, we should check port 80 of the pods. Therefore, we need to find the IP of each pod by simply using this command:
kubectl get pods -o wide
And it should give you sth similar to this:
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-deployment-57d84f57dc-6wk4h 1/1 Running 0 3m22s 10.244.0.10 minikube <none> <none>
...
In my case the IP of Pod is 10.244.0.10 which I should connect to the cluster and check port 80 of that. In Minikube we can SSH to the cluster simply with:
minikube ssh
Now check the <IP>:<PORT> with this command:
curl 10.244.0.10
If you get an output like this:
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
It means your Nginx is working properly on the specified port. So you have a cluster with two Pods, each running an Nginx service.
This was the most basic deployment on Kubernetes, but every big thing is made up of small pieces. In the next posts, I will try to delve deeper into Kubernetes.
If you want to expose your service to outside to see in the browser you can use a LoadBalancer service like this:
apiVersion: v1
kind: Service
metadata:
name: nginx-load-balancer
spec:
selector:
app: nginx
ports:
- protocol: TCP
port: 80
targetPort: 80
type: LoadBalancer
Apply it with:
kubectl apply -f load-balancer.yaml
And you should see an Nginx default page in your IP address.
Have a good time! :)
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