Using kubernetes pulumi.com with jetstream.nats.io

Question

Pulumi · Accepted Answer

Using Pulumi to manage Kubernetes resources allows you to define the desired state of your infrastructure using code. In a Kubernetes context, this could involve deploying applications, configuring networking policies, setting up storage, and more. When working with `jetstream.nats.io`, you may desire to set up NATS Jetstream as a messaging system within your Kubernetes cluster.

To demonstrate how to accomplish this, we'll write a Pulumi program using TypeScript that deploys NATS Jetstream to a Kubernetes cluster. We'll do this by applying Kubernetes manifest definitions using Pulumi which describe our NATS Jetstream StatefulSets, Services, and other necessary resources.

Let's start with a step-by-step program:
1. We'll first set up our imports and initialize a Pulumi Kubernetes provider.
2. Next, we'll define our NATS Jetstream resources as per jetstream.nats.io installation instructions, but expressed in a Pulumi program.
3. We'll use Pulumi's `ConfigGroup` resource to apply our YAML configuration directly.

Before getting into the code, ensure you have:
- Pulumi CLI installed and configured for use with your desired Kubernetes cluster.
- `kubectl` command-line tool installed and configured to communicate with your Kubernetes cluster.
- Access to a Kubernetes cluster where you have permissions to deploy applications.

Now, let's write the Pulumi program:

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

// Initialize a Kubernetes provider by using the context of the currently selected Kubernetes context from your kubeconfig.
const provider = new k8s.Provider('k8s-provider');

// Here's a sample manifest for deploying NATS Jetstream; this would be adjusted depending on your specific configuration needs.
const natsJetstreamManifest = `
---
apiVersion: v1
kind: Namespace
metadata:
  name: nats-io
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: nats
  namespace: nats-io
spec:
  selector:
    matchLabels:
      app: nats
  serviceName: "nats"
  replicas: 3
  template:
    metadata:
      labels:
        app: nats
    spec:
      containers:
      - name: nats
        image: nats:2.2.6-alpine
        args:
        - "server"
        - "--jetstream"
        ports:
        - name: client
          containerPort: 4222
        - name: cluster
          containerPort: 6222
        - name: monitor
          containerPort: 8222
        - name: metrics
          containerPort: 7777
---
apiVersion: v1
kind: Service
metadata:
  name: nats
  namespace: nats-io
spec:
  selector:
    app: nats
  clusterIP: None
  ports:
  - name: client
    port: 4222
  - name: cluster
    port: 6222
`;

// Create a new Pulumi Kubernetes resource (ConfigGroup) which defines a set of Kubernetes objects from the manifest.
const natsJetstreamResources = new k8s.yaml.ConfigGroup('nats-jetstream', {
    yaml: natsJetstreamManifest,
}, { provider });

// Export the namespace of NATS Jetstream so it can be easily accessed by the user, if needed.
export const natsNamespace = natsJetstreamResources.getResource('v1/Namespace', 'nats-io').metadata.name;
```

In the above program:

- We import the necessary Pulumi and Kubernetes libraries.
- We create a provider that will communicate with our Kubernetes cluster.
- We define the YAML manifest for NATS Jetstream, consisting of a `Namespace` for isolation, a `StatefulSet` for the NATS servers, and a `Service` to expose NATS within the cluster.
- We then convert that YAML into Kubernetes resources that Pulumi can manage using the `ConfigGroup` class. The `ConfigGroup` takes in the YAML as a string and automatically generates Pulumi resources for each Kubernetes object defined in the YAML.
- Afterward, we export the namespace which NATS Jetstream is installed into, which can be useful for later reference or for other parts of your infrastructure setup that might interface with NATS.

This program code is just a starting point and you may need to adjust the NATS Jetstream configuration to match your specific requirements. More information on modifying the setup for NATS Jetstream can be found at the [Jetstream documentation](https://docs.nats.io/jetstream/jetstream).

Once you have your TypeScript program ready, you can create a new Pulumi stack and deploy it by running `pulumi up`. Pulumi will then show you a preview of the changes and, upon confirmation, will apply the manifests to your Kubernetes cluster to deploy NATS Jetstream.