Deploy the rke2-coredns helm chart on Linode Kubernetes Engine

Question

Pulumi · Accepted Answer

To deploy the `rke2-coredns` helm chart on a Kubernetes cluster within Linode Kubernetes Engine (LKE), you will need to follow a few steps:

1. **Set up a Linode Kubernetes Engine cluster**: To deploy Helm charts, you need an existing Kubernetes cluster. If you already have a Linode Kubernetes Engine cluster, you can use it. Otherwise, you would need to create one. There is a Pulumi resource for creating a cluster on Linode, but since we don't have specific registry results for Linode, I will assume you have this set up already.

2. **Install the Pulumi Kubernetes provider**: This provider allows you to create, update, and manage Kubernetes resources with Pulumi.

3. **Deploy the Helm Chart**: You will define a Helm chart resource in your Pulumi program and specify the necessary parameters, such as the Helm chart name, repository, and any configurations required by the `rke2-coredns` chart.

Now, let's walk through a TypeScript Pulumi program that deploys the `rke2-coredns` Helm chart to an existing Linode Kubernetes cluster.

First, ensure you have the following prerequisites completed:

- You must have Pulumi CLI installed on your machine.
- You should have `kubectl` configured with access to your Linode Kubernetes cluster.
- Node.js and npm must be installed to run the Pulumi program in TypeScript.

We will now write the Pulumi program:

```typescript
import * as k8s from "@pulumi/kubernetes";

// Create a Kubernetes provider instance using the context of your Linode Kubernetes cluster.
// Ensure your `kubectl` is configured with the context for the LKE.
const provider = new k8s.Provider("lke-k8s", {
    // `context` is omitted to use the current context from the `kubectl` config by default.
});

// Deploy the rke2-coredns Helm chart.
const corednsChart = new k8s.helm.v3.Chart("rke2-coredns", {
    // Specify the chart name and repository URL where the chart can be found.
    // You may need to update the repository URL to the one that hosts the rke2-coredns chart.
    chart: "coredns",
    repo: "https://charts.rancher.io", 
    
    // Specify the namespace and version of the chart if needed
    namespace: "kube-system", // This is a common namespace for core system services in Kubernetes.
    version: "1.16.1", // Use the appropriate version number for the rke2-coredns chart.

// Add any custom values you want to pass to the Helm chart. For example:
    values: {
        // These values would depend on the specific configuration options that the `rke2-coredns` chart supports.
        // Replace these with actual configuration keys and values as necessary.
        replicas: 2,
        serviceType: "ClusterIP",
    },
}, { provider });

// Export the ClusterIP of the CoreDNS service.
export const corednsClusterIP = corednsChart.getResourceProperty("v1/Service", "coredns", "spec.clusterIP");
```

In this code, the `@pulumi/kubernetes` package is used to interact with Kubernetes resources. A new instance of a Kubernetes provider is created to interact with your existing Linode Kubernetes Engine cluster by using the current context from your `kubectl` config file; this does not create a new LKE cluster.

A Helm chart is instantiated using `k8s.helm.v3.Chart`. It's crucial to specify the correct Helm chart name `coredns` and repository URL that should correspond to where the `rke2-coredns` chart is located. You need to ensure that the namespace (`kube-system` by default) and the chart version are specified as required.

We export the ClusterIP of the deployed CoreDNS service so that you can access it if necessary.

Please remember to replace `repo`, `namespace`, `version`, and items in `values` with appropriate values for the `rke2-coredns` chart you are deploying.

You run this program by executing `pulumi up`, which will perform the deployment as described in the code. If successful, you should see the resources created and the ClusterIP of the CoreDNS service being exported.