Deploy the prometheus-storage-adapter helm chart on Linode Kubernetes Engine

Question

Pulumi · Accepted Answer

To deploy a Helm chart on the Linode Kubernetes Engine (LKE) using Pulumi, you can leverage the Pulumi Kubernetes provider. Below is an explanation and a Pulumi TypeScript program that demonstrates how to do this.

Firstly, you should have the Linode Kubernetes Engine cluster already established. If you don't, you can create one using Pulumi as well, but for the sake of this explanation, I'll assume that the cluster is ready and your `kubeconfig` file is correctly set up to communicate with your LKE cluster.

Pulumi works by defining resources as code. In this case, we will define a Helm Chart resource which represents the Prometheus storage adapter you want to deploy. The Kubernetes provider's `helm.v3.Chart` class is designed to work with Helm charts, much like using the Helm CLI, giving you the benefits of Infrastructure as Code.

Here is a step-by-step TypeScript program for deploying a Helm chart to an existing Kubernetes cluster with Pulumi:

1. **Importing necessary modules**: We’ll begin by importing the `@pulumi/kubernetes` module which includes the Helm Chart resources we need.
  
2. **Defining the Helm Chart**: Next, we'll create an instance of `kubernetes.helm.v3.Chart` which will install the Prometheus storage adapter chart from a specified repository. You can customize the settings by providing a `values` object which holds configuration options that override the defaults set by the Helm chart.

Here's the Pulumi program written in TypeScript:

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

// Replace with your own chart values
const prometheusStorageAdapterValues = {
    // Add necessary chart values here
};

const prometheusStorageAdapterChart = new kubernetes.helm.v3.Chart("prometheus-storage-adapter", {
    // Specify the chart repository here
    repo: "prometheus-community",
    chart: "prometheus-storage-adapter",
    version: "1.0.0", // replace with the chart version you want to deploy
    namespace: "monitoring", // specify the namespace where you want to deploy
    values: prometheusStorageAdapterValues,
});

// Export the base URL for the Prometheus storage adapter service, once deployed
export const adapterServiceUrl = prometheusStorageAdapterChart.getResourceProperty(
    "v1/Service", "monitoring", "prometheus-storage-adapter", "status"
).apply(status => `http://${status.loadBalancer.ingress[0].hostname}`);
```

A few notes about this code:

- The `repo` is set to where your chart is located - if Prometheus community charts are hosted on a specific Helm repository, you should put that instead of `"prometheus-community"`.
- `chart`, `version`, and `namespace` are placeholders and should be replaced with actual values that make sense for your setup. The `chart` field should match the name of the chart for the Prometheus storage adapter, and `version` should match the version of the chart that you want to deploy.
- `prometheusStorageAdapterValues` is an object where you can place any values you want to override from the default chart values - deeper nesting within this object will correspond to the nested structure of chart values.
- `adapterServiceUrl` is an export that you'll be able to see the output of once the deployment is complete. It assumes that your service is of type LoadBalancer (common for cloud providers); however, if your setup does not use a LoadBalancer service type or if you’re handling ingress in another way, you’ll need to adapt this line.

Once you've set up your Pulumi project and this program, running `pulumi up` will apply the configuration. Pulumi will communicate with your Kubernetes cluster, process the Helm chart, deploy the defined resources, and provision the Prometheus storage adapter according to your specifications.

If you run into any issues or have further questions as you use this code, please let me know!