Using kubernetes karpenter.sh with certmanager.k8s.io

Question

Pulumi · Accepted Answer

To use Kubernetes with the Karpenter autoscaling project and cert-manager for managing TLS certificates, you would typically do the following:

1. **Set up Karpenter**: Karpenter is an open-source, flexible, high-performance Kubernetes cluster autoscaler built by AWS that helps improve the efficiency and cost of running workloads on Kubernetes. It works alongside the Kubernetes scheduler to efficiently manage node provisioning. You would install Karpenter on your cluster and configure it to work with your preferred cloud provider.

2. **Install cert-manager**: cert-manager is a native Kubernetes certificate management controller. It can help with issuing certificates from a variety of sources, such as Let's Encrypt, HashiCorp Vault, Venafi, a simple signing key pair, or self-signed. It ensures certificates are valid and up to date and attempts to renew certificates at a configured time before expiry.

In a Pulumi program, you would define a stack that includes resources for both Karpenter and cert-manager using their respective Helm charts. Below is a TypeScript program for Pulumi that demonstrates how you might set up these tools on a Kubernetes cluster.

Please note that this example assumes you have a Kubernetes cluster already running and kubectl configured to communicate with it. Also, make sure you have Pulumi installed and configured for TypeScript.

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

// The following Helm chart installation will set up cert-manager in your Kubernetes cluster.
const certManagerChart = new k8s.helm.v3.Chart("cert-manager", {
    chart: "cert-manager",
    version: "v1.3.2",
    namespace: "cert-manager",
    fetchOpts:{
        repo: "https://charts.jetstack.io",
    },
    values: {
        installCRDs: true, // This will install the Custom Resource Definitions needed for cert-manager.
    },
});

// Similarly, you can install Karpenter using a Helm chart.
const karpenterChart = new k8s.helm.v3.Chart("karpenter", {
    chart: "karpenter",
    version: "v0.4.3",
    namespace: "karpenter",
    fetchOpts: {
        repo: "https://charts.karpenter.sh/",
    },
    values: {
        // You will need to replace these values with ones that correspond to your setup.
        clusterName: "your-cluster-name",
        clusterEndpoint: "your-cluster-endpoint",
        aws: {
            // Specify AWS region where your Kubernetes cluster is deployed
            region: "us-west-2",
        },
    },
});

export const certManagerNamespace = certManagerChart.namespace;
export const karpenterNamespace = karpenterChart.namespace;
```

This program uses the Pulumi Kubernetes provider to install `cert-manager` and Karpenter on your Kubernetes cluster via their Helm charts, by specifying the chart and version, as well as any required values.

- The `certManagerChart` resource installs `cert-manager` and also specifies to install the Custom Resource Definitions (CRDs) necessary for it to function.
- The `karpenterChart` resource installs Karpenter. You need to replace `"your-cluster-name"` and `"your-cluster-endpoint"` with appropriate values for your Kubernetes cluster. Additionally, specify the AWS region where your Kubernetes cluster is located.

Once those resources are defined in your Pulumi program, you can simply run `pulumi up` from your command line to apply the configuration to your cluster. This operation will orchestrate the deployment and management of the necessary Helm charts on the cluster.

Finally, the program exports the namespaces `certManagerNamespace` and `karpenterNamespace` where `cert-manager` and Karpenter are installed, respectively, which can be useful if you want to interact with these components using `kubectl` or other Kubernetes tools.