Deploy the mongo helm chart on Linode Kubernetes Engine

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Pulumi · Accepted Answer

Deploying a Helm chart on a Kubernetes cluster is a two-step process:

1. **Provision the Kubernetes Cluster**: You need a Kubernetes cluster running before you can deploy any applications to it. With Pulumi, you can define and provision the cluster in your preferred cloud environment using code. Below, we'll demonstrate how to provision a Linode Kubernetes Engine (LKE) cluster using Pulumi.
   
2. **Deploy the Mongo Helm Chart**: Once you have a cluster running, you can deploy applications using Helm charts. Helm is a package manager for Kubernetes that simplifies deployment.

### Provisioning a Linode Kubernetes Engine (LKE) Cluster

To provision an LKE cluster, you'd typically use the Pulumi Linode provider. However, at the time of writing, Linode support in Pulumi was not available in the registry results. Because of this, I'm going to show you how to deploy the MongoDB Helm chart on a general Kubernetes cluster. You can apply the same principles to an LKE cluster once you have it instantiated.

### Deploying the MongoDB Helm Chart

For deploying the Helm chart, we'll use the `kubernetes.helm.v3.Chart` resource from the Pulumi Kubernetes provider. This resource allows you to deploy Helm charts to your Kubernetes cluster.

Here's the full Pulumi program to deploy MongoDB Helm chart on a Kubernetes cluster, using TypeScript:

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

// Note: The following code assumes that you have a Kubernetes cluster running and your kubeconfig is set.

// Create a Kubernetes namespace for the MongoDB deployment.
const namespace = new k8s.core.v1.Namespace("mongo-namespace", {
  metadata: {
    name: "mongo",
  },
});

// Deploy the MongoDB Helm chart.
const mongoChart = new k8s.helm.v3.Chart("mongo-chart", {
  chart: "mongodb",
  version: "10.8.1", // specify the version you wish to use
  namespace: namespace.metadata.name,
  fetchOpts: {
    repo: "https://charts.bitnami.com/bitnami", // MongoDB Helm chart is available in Bitnami's Helm repository
  },
  // Override default values from the Helm chart (if necessary).
  values: {
    replicaCount: 1,
    // ... Add other custom configuration if required.
  },
});

// Export the name of the namespace
export const mongoNamespace = namespace.metadata.name;
```

### Explanation

- First, we import the `@pulumi/kubernetes` library, which provides the classes and functions needed to interact with Kubernetes resources.

- We create a new Kubernetes namespace specifically for MongoDB using the `k8s.core.v1.Namespace` class. This is where our MongoDB Helm chart will be deployed. Namespaces help you organize resources in your cluster.

- Next, we use the `k8s.helm.v3.Chart` class to deploy the MongoDB Helm chart. We specify the chart name (`mongodb`), the version, and the repository URL where the MongoDB chart is located.

- We use the `values` property in the `k8s.helm.v3.Chart` to override any default configuration provided by the chart. We're setting `replicaCount: 1` as an example, but you could include any other Helm values as needed.

- Finally, we export the namespace metadata's name so that you can easily identify the namespace where MongoDB was deployed.

To run this Pulumi program:

1. Make sure you have Pulumi CLI installed and have authenticated with your cloud provider.
2. Save this code in a TypeScript file, for example, `index.ts`.
3. Run `pulumi up` to execute the code and provision the resources.

Remember, this code snippet only works if you have a configured Kubernetes cluster. If you need to set up an LKE cluster, you would typically use the Linode provider for Pulumi to manage Linode resources, which would look similar to other provider usages in Pulumi. Once Linode is supported in Pulumi, the instantiation of an LKE cluster would precede the deployment of the mongo chart.