Automating Disk Management in Kubernetes with OpenEBS DiskPool

Question

Pulumi · Accepted Answer

OpenEBS is an open-source storage platform that enables the use of storage devices across a Kubernetes cluster. It allows for managing the lifecycle of local and remote disks attached to the nodes and facilitates dynamic provisioning of volumes as needed by the applications running in the cluster.

To create an OpenEBS DiskPool in Kubernetes using Pulumi, we'll consider a scenario where the Kubernetes cluster is up and running. We will use Pulumi to define the necessary resources in the Kubernetes manifest yaml format such as DiskPool CRD (Custom Resource Definition), which is used by OpenEBS for disk management.

The following steps and program will guide you on how to automate the creation of a DiskPool in Kubernetes with OpenEBS:

1. Define the DiskPool CRDs needed for OpenEBS: You need to apply the Custom Resource Definitions that OpenEBS uses for managing disk pools.
2. Create a DiskPool resource: After the CRDs are established, you create a DiskPool resource and specify characteristics like node selector, disk types to include, etc.
3. Apply DiskPool to your cluster: Use Pulumi to apply this configuration to your Kubernetes cluster.

Below is a program written in TypeScript outlining how you could define the DiskPool CRD using Pulumi for OpenEBS. For this example, we're assuming OpenEBS is already installed on your Kubernetes cluster.

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

const diskPool = new kubernetes.apiextensions.CustomResource("openEBS-diskPool", {
    apiVersion: "openebs.io/v1alpha1",
    kind: "DiskPool",
    metadata: {
        // Replace with the actual namespace if OpenEBS is installed in a specific namespace.
        namespace: "default",
    },
    spec: {
        // The following spec is an example, and the actual spec would depend on your requirements.
        pools: [{
            nodeSelector: {  
                // Node selector to target specific nodes for the pool.
                "kubernetes.io/hostname": "example-node",
            },
            disks: {
                // Define the disk types and attributes.
                diskList: [
                    // List the devices (disk paths) that should be included in the disk pool.
                    // Replace with the actual disk paths.
                    "/dev/sdb",
                    "/dev/sdc",
                ],
            },
        }],
    },
});

// Export the disk pool name so that we can easily reference it.
export const diskPoolName = diskPool.metadata.name;
```

In the above code:

- We import the Kubernetes package from Pulumi, which allows you to interact with Kubernetes resources.
- We define a custom resource named `openEBS-diskPool` using the `CustomResource` class.
- We set the `apiVersion` to match that of the OpenEBS DiskPool CRD and kind as `DiskPool`, which is specific to OpenEBS.
- The `metadata.namespace` is set to `default`, which should be replaced with the namespace where OpenEBS is installed.
- In the `spec`, we define a single pool with a `nodeSelector` that targets a specific node with the label `kubernetes.io/hostname` set to `example-node`. You'll need to modify the selector to target the node where you intend to create the disk pool.
- The `disks.diskList` is an array where you list the paths of physical/virtual disks you want to include in your disk pool. Update this with your actual disk paths.
- Finally, we export the disk pool name for easy reference in future Pulumi stacks or outputs.

Please make sure to replace placeholders with values that match your environment and adapt the specification to fit the requirements of your cluster and OpenEBS configuration. Before running this Pulumi program, ensure that you have configured Pulumi with access to your Kubernetes cluster and that OpenEBS CRDs are installed in the cluster.

To run this program, you will need to have Pulumi CLI installed, and simply execute `pulumi up` after navigating to the directory containing your Pulumi TypeScript program. This will prompt Pulumi to begin provisioning the resources as defined by your code. Upon completion, it will output any exported variables, such as `diskPoolName` in this case.