Deploy the kube-dns helm chart on Opensshift

Question

Pulumi · Accepted Answer

To deploy the `kube-dns` Helm chart on OpenShift, you'll need to use the Pulumi Kubernetes provider, which enables you to write code to define and manage Kubernetes resources, including deploying Helm charts.

Before you begin, make sure you are logged into your OpenShift cluster where you want to deploy `kube-dns`, and that you have `kubectl` configured to communicate with your cluster.

The `kube-dns` Helm chart provides a method to install the `kube-dns` service which is a DNS server for service discovery in Kubernetes. It is included in many Kubernetes setups by default. You will need to use the Helm chart resource in Pulumi to deploy `kube-dns`. Typically, `kube-dns` might not need explicit installation as it's usually installed and managed as a core cluster service by the cloud provider's Kubernetes offering.

Below is the Pulumi TypeScript program that demonstrates how to deploy the `kube-dns` Helm chart to an OpenShift cluster:

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

const kubeDnsChart = new k8s.helm.v3.Chart("kube-dns", {
    // The OpenShift cluster should provide a kubeconfig for authentication.
    // It is often at ~/.kube/config, and Pulumi will automatically use it.
    // The chart name is 'kube-dns' and it should be available in the default Helm repository.
    chart: "kube-dns",
    // Specify the namespace where kube-dns should be installed.
    // If it's a component of the OpenShift cluster, it should typically go into 'kube-system'.
    namespace: "kube-system",
    // Values to pass to the kube-dns helm chart to customize the deployment as necessary.
    values: {
        // Placeholder for any values you might want to pass to the Helm chart.
        // For example, you might want to configure custom resource limits or affinities.
    },
    // You may need to specify the Helm repository where the kube-dns chart is located,
    // unless it's in the default repositories that Helm is aware of.
    // You can omit the `repo` property if the chart is a standard one.
    repo: "https://some-helm-chart-repo.com",
    // OpenShift and kube-dns specifics can be set here, check the values.yaml in the chart for more options.
});

// To access the DNS service, you might want to export the service endpoint or other useful information.
export const kubeDnsServiceName = kubeDnsChart.getResourceProperty("v1/Service", "kube-dns", "metadata").apply(metadata => metadata.name);

```

This program uses the `@pulumi/kubernetes` package to manage Kubernetes resources via Pulumi. It creates a new Helm chart resource, `kube-dns`, in the `kube-system` namespace (typical for such core services). It specifies the name of the chart and optionally defines custom values and a Helm repository if it's not included in the chart's default repos.

Note:
- The `kube-dns` chart may not exist in the public Helm repositories; this is a placeholder for demonstration.
- `kube-dns` is typically installed by default on Kubernetes clusters, but in case you need to install it separately or customize it, this code shows you how.
- Always check the documentation for the specific chart you're working with for the correct values and configurations.

This code assumes the Helm chart is named `kube-dns` and is available in a Helm repository. Modify the placeholders as needed with actual values from the chart documentation.

In this code, we do not specify a path to the kubeconfig because Pulumi will default to using the active kubeconfig from the environment. Ensure you have the correct kubeconfig context selected for the OpenShift cluster where you want to make the deployment.

After you've written your Pulumi program, you will need to run it through the Pulumi CLI to perform the deployment:

```bash
pulumi up
```

This command will compile the TypeScript program, show you a preview of the resources that will be created, and prompt you to confirm the deployment. Once confirmed, Pulumi will deploy the `kube-dns` Helm chart to your OpenShift cluster.