Using kubernetes cilium.io with nats

Question

Pulumi · Accepted Answer

To integrate Cilium, which is a networking plugin, with a Kubernetes cluster and deploy NATS, a messaging system, we will follow certain steps. First, we'll need a Kubernetes cluster, which can be provisioned using Pulumi. Then, we will install Cilium into the cluster as the networking solution. Cilium will be responsible for providing networking capabilities that support L3/L4 load balancing, and network policies for the Kubernetes pods. Lastly, we'll deploy NATS, the messaging system, within the Kubernetes cluster, which will enable high-performance messaging among our services.

Let's start by creating a new Kubernetes cluster using Pulumi with Azure as our cloud provider. We'll use the `azure-native:containerservice:ManagedCluster` resource to create an AKS cluster that supports network policies, which are necessary for Cilium. Then, we will use Kubernetes resources like `ConfigMap`, `DaemonSet`, and others to install Cilium. Lastly, we will deploy NATS within the Kubernetes cluster using Kubernetes resources such as `Deployment` and `Service`.

Below is the program in TypeScript which demonstrates this setup:

```typescript
import * as pulumi from "@pulumi/pulumi";
import * as azure_native from "@pulumi/azure-native";
import * as k8s from "@pulumi/kubernetes";

// Create an AKS cluster
const aksCluster = new azure_native.containerservice.ManagedCluster("aksCluster", {
    // Ensure that network policy support is enabled, which is required for Cilium
    networkProfile: {
        networkPlugin: "azure",
        networkPolicy: "calico", // Even though we're using Cilium, specify Calico here to enable network policy support in AKS
    },
    // Additional required AKS configuration...
    // ...
});

// Exposing the kubeconfig
const kubeconfig = pulumi.secret(aksCluster.kubeConfigRaw);

// Creating a provider to enable us to deploy resources into the AKS cluster
const provider = new k8s.Provider("aksProvider", {
    kubeconfig: kubeconfig,
});

// Deploying Cilium with Helm
const cilium = new k8s.helm.v3.Chart("cilium", {
    chart: "cilium",
    version: "1.10.4",
    fetchOpts: {
        repo: "https://helm.cilium.io/",
    },
}, { provider: provider });

// Deploying NATS with Helm
const nats = new k8s.helm.v3.Chart("nats", {
    chart: "nats",
    version: "0.7.3",
    fetchOpts: {
        repo: "https://nats-io.github.io/k8s/helm/charts/",
    },
}, { provider: provider });

// Export the kubeconfig and cluster name
export const kubeConfig = kubeconfig;
export const clusterName = aksCluster.name;
```

### Explanation

1. We define an AKS cluster using `azure_native.containerservice.ManagedCluster`, providing necessary details like the `networkProfile`. Azure network policies are set to enable the network plugin and network policy enforcement, which Cilium will utilize.
   
2. A Kubernetes provider is instantiated which is used to deploy resources to the AKS cluster. `kubeconfig` is derived from the AKS cluster resource and marked as a secret to ensure it's not exposed.

3. We install Cilium into the cluster via `k8s.helm.v3.Chart`. We use the Cilium chart from its official repository. In the helm chart, we specify the version to ensure the chart used is compatible with our setup.

4. Similarly, we deploy NATS using its official helm chart, specifying the version and repository.

5. We export both `kubeconfig` and `clusterName` which can be used outside the Pulumi program to interact with the cluster and workloads.

Remember to replace the placeholder comments (the parts with `//...`) with the actual values and configurations as per the cluster's requirements. Adjust resource names, versions, or settings as appropriate for your use case.

Please be aware that the versions specified in the Helm chart are just examples and should be replaced with the specific versions you intend to use. Make sure to consult the official [Cilium documentation](https://docs.cilium.io) and [NATS documentation](https://docs.nats.io) for the required versions and further configuration options you may need.