Using kubernetes pkg.crossplane.io with kubernetes.crossplane.io

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Pulumi · Accepted Answer

## Crossplane on Kubernetes with Pulumi

Crossplane is an open-source Kubernetes add-on that transforms your cluster into a universal control plane. It allows you to manage your infrastructure and services in public and private clouds directly from Kubernetes. You can provision and manage databases, caches, and Kubernetes clusters from multiple cloud providers alongside your application workloads.

Pulumi, an infrastructure as code tool, can be used to deploy and manage Crossplane as well as the resources it manages on a Kubernetes cluster. Below, I will show you how to set up Crossplane using Pulumi, and how you might configure it to manage resources in a cloud provider.

Before you begin, you should have Pulumi, `kubectl`, and Crossplane `kubectl` plugin installed on your machine. You should also have a Kubernetes cluster running and have the `kubeconfig` file pointing to it.

Our program will do the following:
1. Install the Crossplane into the Kubernetes cluster.
2. Set up a provider for Crossplane to manage resources in a specific cloud (e.g., AWS, GCP, Azure).
3. Define a custom resource that Crossplane can manage using its controllers.

Let's start by writing a Pulumi program that deploys Crossplane on Kubernetes:

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

// Create a Pulumi Kubernetes provider that uses our existing kubeconfig
const k8sProvider = new k8s.Provider('k8s-provider', { kubeconfig: process.env.KUBECONFIG });

// Install Crossplane using Helm chart
const crossplaneChart = new k8s.helm.v3.Chart('crossplane', {
  chart: 'crossplane',
  version: '1.0.0',
  fetchOpts: {
    repo: 'https://charts.crossplane.io/stable/',
  },
}, { provider: k8sProvider });

// Log the status of the helm chart
export const crossplaneStatus = crossplaneChart.status;

console.log('Crossplane has been successfully deployed on Kubernetes.');
```

In this program, we first import the `@pulumi/kubernetes` package to interact with Kubernetes resources. We create a Kubernetes provider by passing our `kubeconfig`. This allows Pulumi to communicate with our Kubernetes cluster.

We then define a `Chart` resource representing the Crossplane Helm chart. Pulumi will install the Crossplane control plane into our Kubernetes cluster using this chart.

After deploying Crossplane, the next step is to configure a provider for Crossplane. Since the specifics of this step depend on the actual cloud provider you're using and the credentials required, the following code is a generic example that would require filling in the specific details for your cloud provider:

```typescript
// Define a Crossplane ProviderConfig for AWS
const awsProviderConfig = new k8s.yaml.ConfigGroup('aws-provider-config', {
  files: "aws-provider-config.yaml",
}, { provider: k8sProvider });
```

In this example, `aws-provider-config.yaml` would be a Kubernetes YAML file that contains the Crossplane configuration for AWS, including how to authenticate to the AWS API.

Finally, you could define a custom resource that the Crossplane can manage. For instance, creating a PostgreSQL instance on AWS RDS:

```typescript
// Define a PostgreSQLInstance custom resource
const postgreSQLInstance = new k8s.yaml.ConfigGroup('postgres-db', {
  files: "postgres-db.yaml",
}, { provider: k8sProvider });
```

Here, `postgres-db.yaml` would be another Kubernetes YAML file that specifies the resource definition for a PostgreSQL instance on AWS RDS following Crossplane's schema for that resource.

These custom resource files are not defined within this Pulumi program, as they are Kubernetes YAML specifications typically written separately. These YAML files include information such as the resource classes, their sizes, regions, and any other specifications required to provision resources on the cloud provider.

In this way, Pulumi and Crossplane work together to manage cloud resources through Kubernetes. Crossplane extends Kubernetes to allow it to manage cloud services directly, providing a single API and point of control, while Pulumi allows developers to express the desired state of their infrastructure using familiar programming languages.

Remember, the above program is a starting point and would need actual configurations and resources specified in separate YAML files. Ensure that you have the right configuration and your cloud provider credentials in place before running the Pulumi program.