Installing on Linode Kubernetes Engine (LKE)

This guide walks through the process of installing and configuring SpinKube on Linode Kubernetes Engine (LKE).

Prerequisites

This guide assumes that you have an Akamai Linode account that is configured and has sufficient permissions for creating a new LKE cluster.

You will also need recent versions of kubectl and helm installed on your system.

Creating an LKE Cluster

LKE has a managed control plane, so you only need to create the pool of worker nodes. In this tutorial, we will create a 2-node LKE cluster using the smallest available worker nodes. This should be fine for installing SpinKube and running up to around 100 Spin apps.

You may prefer to run a larger cluster if you plan on mixing containers and Spin apps, because containers consume substantially more resources than Spin apps do.

In the Linode web console, click on Kubernetes in the right-hand navigation, and then click Create Cluster.

You will only need to make a few choices on this screen. Here’s what we have done:

• We named the cluster spinkube-lke-1. You should name it according to whatever convention you prefer
• We chose the Chicago, IL (us-ord) region, but you can choose any region you prefer
• The latest supported Kubernetes version is 1.30, so we chose that
• For this testing cluster, we chose No on HA Control Plane because we do not need high availability
• In Add Node Pools, we added two Dedicated 4 GB simply to show a cluster running more than one node. Two nodes is sufficient for Spin apps, though you may prefer the more traditional 3 node cluster. Click Add to add these, and ignore the warning about minimum sizes.

Once you have set things to your liking, press Create Cluster.

This will take you to a screen that shows the status of the cluster. Initially, you will want to wait for all of your Node Pool to start up. Once all of the nodes are online, download the kubeconfig file, which will be named something like spinkube-lke-1-kubeconfig.yaml.

The kubeconfig file will have the credentials for connecting to your new LKE cluster. Do not share that file or put it in a public place.

For all of the subsequent operations, you will want to use the spinkube-lke-1-kubeconfig.yaml as your main Kubernetes configuration file. The best way to do that is to set the environment variable KUBECONFIG to point to that file:

$ export KUBECONFIG=/path/to/spinkube-lke-1-kubeconfig.yaml

You can test this using the command kubectl config view:

$ kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: https://REDACTED.us-ord-1.linodelke.net:443
  name: lke203785
contexts:
- context:
    cluster: lke203785
    namespace: default
    user: lke203785-admin
  name: lke203785-ctx
current-context: lke203785-ctx
kind: Config
preferences: {}
users:
- name: lke203785-admin
  user:
    token: REDACTED

This shows us our cluster config. You should be able to cross-reference the lkeNNNNNN version with what you see on your Akamai Linode dashboard.

Install SpinKube Using Helm

At this point, install SpinKube with Helm. As long as your KUBECONFIG environment variable is pointed at the correct cluster, the installation method documented there will work.

Once you are done following the installation steps, return here to install a first app.

Creating a First App

We will use the spin kube plugin to scaffold out a new app. If you run the following command and the kube plugin is not installed, you will first be prompted to install the plugin. Choose yes to install.

We’ll point to an existing Spin app, a Hello World program written in Rust, compiled to Wasm, and stored in GitHub Container Registry (GHCR):

$ spin kube scaffold --from ghcr.io/spinkube/containerd-shim-spin/examples/spin-rust-hello:v0.13.0 > hello-world.yaml

Note that Spin apps, which are WebAssembly, can be stored in most container registries even though they are not Docker containers.

This will write the following to hello-world.yaml:

apiVersion: core.spinkube.dev/v1alpha1
kind: SpinApp
metadata:
  name: spin-rust-hello
spec:
  image: "ghcr.io/spinkube/containerd-shim-spin/examples/spin-rust-hello:v0.13.0"
  executor: containerd-shim-spin
  replicas: 2

Using kubectl apply, we can deploy that app:

$ kubectl apply -f hello-world.yaml
spinapp.core.spinkube.dev/spin-rust-hello created

With SpinKube, SpinApps will be deployed as Pod resources, so we can see the app using kubectl get pods:

$ kubectl get pods
NAME                              READY   STATUS    RESTARTS   AGE
spin-rust-hello-f6d8fc894-7pq7k   1/1     Running   0          54s
spin-rust-hello-f6d8fc894-vmsgh   1/1     Running   0          54s

Status is listed as Running, which means our app is ready.

Making An App Public with a NodeBalancer

By default, Spin apps will be deployed with an internal service. But with Linode, you can provision a NodeBalancer using a Service object. Here is a hello-world-service.yaml that provisions a nodebalancer for us:

apiVersion: v1
kind: Service
metadata:
  name: spin-rust-hello-nodebalancer
  annotations:
    service.beta.kubernetes.io/linode-loadbalancer-throttle: "4"
  labels:
    core.spinkube.dev/app-name: spin-rust-hello
spec:
  type: LoadBalancer
  ports:
  - name: http
    port: 80
    protocol: TCP
    targetPort: 80
  selector:
    core.spinkube.dev/app.spin-rust-hello.status: ready
  sessionAffinity: None

When LKE receives a Service whose type is LoadBalancer, it will provision a NodeBalancer for you.

You can customize this for your app simply by replacing all instances of spin-rust-hello with the name of your app.

We can create the NodeBalancer by running kubectl apply on the above file:

$ kubectl apply -f hello-world-nodebalancer.yaml
service/spin-rust-hello-nodebalancer created

Provisioning the new NodeBalancer may take a few moments, but we can get the IP address using kubectl get service spin-rust-hello-nodebalancer:

$ get service spin-rust-hello-nodebalancer
NAME                           TYPE           CLUSTER-IP       EXTERNAL-IP       PORT(S)        AGE
spin-rust-hello-nodebalancer   LoadBalancer   10.128.235.253   172.234.210.123   80:31083/TCP   40s

The EXTERNAL-IP field tells us what the NodeBalancer is using as a public IP. We can now test this out over the Internet using curl or by entering the URL http://172.234.210.123/hello into your browser.

$ curl 172.234.210.123/hello
Hello world from Spin!

Deleting Our App

To delete this sample app, we will first delete the NodeBalancer, and then delete the app:

$ kubectl delete service spin-rust-hello-nodebalancer
service "spin-rust-hello-nodebalancer" deleted
$ kubectl delete spinapp spin-rust-hello
spinapp.core.spinkube.dev "spin-rust-hello" deleted

If you delete the NodeBalancer out of the Linode console, it will not automatically delete the Service record in Kubernetes, which will cause inconsistencies. So it is best to use kubectl delete service to delete your NodeBalancer.

If you are also done with your LKE cluster, the easiest way to delete it is to log into the Akamai Linode dashboard, navigate to Kubernetes, and press the Delete button. This will destroy all of your worker nodes and deprovision the control plane.