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This page describes how to create a new Kubernetes cluster via OpenStack Magnum by using Terraform or OpenTofu.

Pre-requisites

The following pre-requisites must be satisfied.

Have read and followed the EWC - IaC via Terraform and OpenTofu page.
The Terraform or OpenTofu CLI installed.
Application credentials to access the Openstack cloud project

There is a set of mandatory inputs required to create a new cluster which are:

flavor_name : the resources (CPU, RAM, Disk) configuration for the VM (see as reference EWC VM plans )
key_pair : configured SSH key which is needed to connect to the VM (see EWC - OpenStack Command-Line client for how to import it )
security_groups : security groups are sets of applied IP filter rules which define networking access to the instance
network : the network to be attached to the VM : external-internet: access to the Internet with public IP ; private-<tenant>: local private network within the tenant.

The available selectable options could also be checked using the Opnstack CLI commands :

$ openstack keypair list
 
$ openstack image list
 
$ openstack flavor list 
 
$ openstack network list

Write configuration files

Create a directory for your configuration and change directory into it:

$ mkdir example-magnum-k8s

$ cd example-magnum-k8s

Create the main configuration file to define the infrastructure:

$ touch main.tf

Open the main.tf file in a text editor and fill it as needed like in the following minimal example :

terraform {
  required_providers {
    openstack = {
      source = "terraform-provider-openstack/openstack"
    }
  }
}

provider "openstack" {
  cloud = "openstack"
}

variable "magnum_cluster_template" {
  description = <<EOT
  The name of the Magnum cluster template to create the kubernetes cluster with

  You may view a list of available template by running `openstack coe cluster template list`
  EOT
  type        = string
  default     = "cluster-template-name"
}

data "openstack_containerinfra_clustertemplate_v1" "clustertemplate" {
  name = var.magnum_cluster_template
}

resource "openstack_containerinfra_cluster_v1" "cluster" {
  name                = "cluster-name"
  cluster_template_id = data.openstack_containerinfra_clustertemplate_v1.clustertemplate.id
  master_count        = "master-count"
  master_flavor       = "master-flavor-name"
  node_count          = "worker-node-count"
  flavor              = "worker-node-flavor-name"
  keypair             = "ssh-keypair"
  fixed_network       = "private-network-name"
  fixed_subnet        = "private-subnet-name"
  labels              = {
     monitoring_enabled   = "true"
     auto_healing_enabled = "true"
     }
  merge_labels        = "true"
  create_timeout      = "180"

}

Replace the following fields as desired:

```
cluster-template-name
```
```
cluster-name
```
```
master-count
```
```
master-flavor-name
```
```
worker-node-count
```
```
worker-node-flavor-name
```

For instance for ECMWF can be :

resource "openstack_compute_instance_v2" "test-server" {
  name            = "test-server"
  image_name      = "Rocky-9.4-20240717094419"
  flavor_name     = "2cpu-2gbmem-30gbdisk"
  key_pair        = "mykey"
  security_groups = ["default", "ssh"]

  network {
    name = "private-cci1-ewcloud-ms-nmhs-project"
  }
}

Run Terraform or OpenTofu to create a Kubernetes cluster via OpenStack Magnum

Initialize the directory :

Terraform

$ terraform init

OpenTofu

$ tofu init

Review the required changes:

$ terraform plan

Apply the changes to create the Kubernetes cluster :

Terraform

$ terraform apply

OpenTofu

$ tofu apply

Status can be then seen via:

Terraform

$ terraform show

OpenTofu

$ tofu show

Destroy the Cluster

The created cluster can be then destroyed by simply running:

Terraform

$ terraform destroy

OpenTofu

$ tofu destroy