Deploy a .net app on a local kind cluster
This guide will help you throught the process of deploying a .Net app on a local kind cluster. I was just curious to see how it works and I decided to write an article about it (after studying the correct way to do it).
Prerequisites
This guide assumes you have alreay installed:
You can follow the guide Deploy a local kind cluster to install all the prerequisites or you can just install kind and ingress-nginx fastes way possible by running the following commands:
kind create cluster --config kind/config.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/kind/deploy.yaml
And you are ready to go!
Create a .Net app
I’ve created a github repo with a simple .Net app that will be deployed on the kind cluster. You can find it here. The app is a simple web api that returns a string or interact with files (to test my understanding of volumes).
You can try it locally by running the following commands:
git clone https://github.com/RoBYCoNTe/hello-world-k8s-net.git
cd hello-world-k8s-net
dotnet restore
dotnet run
The app will be available on port 5000 and you can test it by running the following commands:
curl http://localhost:5000/v1
curl http://localhost:5000/v1/files/append?line=Hello
Create a Dockerfile
Using kubernetes we can deploy a containerized application. To do that we need to create a Dockerfile that will be used to build the image that will be deployed on the cluster.
Inside the repo you can find a Dockerfile already prepared. You can find it here.
Before building the image you have to login into your docker hub account. To do that run the following command:
docker login
Then build the image by running the following command:
docker build -t <your-docker-hub-username>/hello-world-k8s-net:latest .
Push the image to Docker Hub
To push the image to Docker Hub run the following command:
docker push <your-docker-hub-username>/hello-world-k8s-net:latest
Deployment
Now that we have the image ready we can create a deployment that will deploy the image on the cluster. Before creating the deployment you have to instruct your cluster to pull the image from Docker Hub. To do that run the following command:
kubectl create secret docker-registry dockerhub --docker-server=https://index.docker.io/v1/ --docker-username=<your-docker-hub-username> --docker-password=<your-docker-hub-password> --docker-email=<your-docker-hub-email>
With previous command we have created a secret that will be used by the deployment to pull the image from Docker Hub (you cannot pull an image from Docker Hub without a secret). For more information about how to configure a secret to pull an image from Docker Hub you can read this article.
The deployment is defined in the file deployment.yaml. You can find it in the repo.
Before creating the deployment we have to create PVCs that will be used by the deployment to store data. To do that run the following commands:
kubectl apply -f k8s/pv.yaml
kubectl apply -f k8s/pvc.yaml
Without the PVCs the deployment will fail because it will not be able to store data.
Now we can create the deployment by running the following command:
kubectl apply -f k8s/deployment.yaml
Remember to change the image name in the deployment file with your own image name.
Now we can create service and ingress to expose the app to the outside world. To do that run the following commands:
kubectl apply -f k8s/service.yaml
kubectl apply -f k8s/ingress.yaml
Remember to change the host in the ingress file with your own host and to add the host to your /etc/hosts file (if you are using linux) or to your hosts file (if you are using windows).
Test the app
To test the app run the following commands:
curl -H "Host: hello-world-k8s-net.local" http://localhost/v1
You should see the classic “Hello World!” message.
I was just curious to see how volumes work on a local kind cluster. To test it run the following commands:
curl -H "Host: hello-world-k8s-net.local" http://localhost/v1/files/append?line=Hello
If you execute the previous command multiple time you will see that the file is updated with the new line (it is returned by the api). Furthermore if you delete the pod or restart the cluster the file will still be there.
For example, if we redeploy the app by running the following command:
kubectl rollout restart deployment hello-world-k8s-net
Executing the curl command again will return the same result!
Conclusion
This guide was just a way to test how volumes work on a local kind cluster. I’ve learned that volumes are not deleted when you delete a pod or when you restart the cluster. Furthermore I’ve learned that you can use a secret to pull an image from Docker Hub. I’ve to says that first tries were not successful because I was using a wrong secret, missing to install ingress-nginx, missing to create PVC and so on. I’ve learned that you have to read the error messages and try to understand what is going on. Most of the time the error messages are pretty clear and you can understand what is going on, if not you can always ask for help on the internet.
I hope you enjoyed this guide and I hope you learned something new. If you have any question or suggestion please leave a comment below.