The k8s-alpha CLI is deprecated. On March 31st, 2020, it will be removed from the linode-cli. After March 31, 2020, you will no longer be able to create or manage clusters using the k8s-alpha CLI plugin.
However, you will still be able to create and manage these clusters using Terraform. The Terraform module used is a public project officially supported by Linode, and is currently used to power the k8s-alpha CLI.
Other alternatives for creating and managing clusters include: