terraform-openstack-rke2

Terraform module to deploy Kubernetes with RKE2 on OpenStack.

Unlike RKE version this module is not opinionated and let you configure everything via RKE2 configuration file.

Prerequisites

• Terraform 0.13+
• OpenStack environment properly sourced
• A Openstack image fullfiling RKE2 requirements and featuring curl
• At least one Openstack floating IP

Features

• HA controlplane
• Multiple agent node pools
• Upgrade mechanism

Examples

See examples directory.

Documentation

See USAGE.md for all available options.

Keypair

You can either specify a ssh key file to generate new keypair via ssh_key_file (default) or specify already existent keypair via ssh_keypair_name.

⚠️ Default config will try to use ssh agent for ssh connections to the nodes. Add use_ssh_agent = false if you don't use it.

Secgroup

You can define your own rules (e.g. limiting port 22 and 6443 to admin box).

secgroup_rules      = [ { "source" = "x.x.x.x", "protocol" = "tcp", "port" = 22 },
                        { "source" = "x.x.x.x", "protocol" = "tcp", "port" = 6443 },
                        { "source" = "0.0.0.0/0", "protocol" = "tcp", "port" = 80 },
                        { "source" = "0.0.0.0/0", "protocol" = "tcp", "port" = 443}
                      ]

Nodes affinity

You can set affinity policy for controlplane and each nodes pool server_group_affinity. Default is soft-anti-affinity.

⚠️ soft-anti-affinity and soft-affinity needs Compute service API 2.15 or above.

Boot from volume

Some providers require to boot the instances from an attached boot volume instead of the nova ephemeral volume. To enable this feature, provide the variables to the config file. You can use different value for server and agent nodes.

boot_from_volume = true
boot_volume_size = 20
boot_volume_type = "rbd-1"

Kubernetes version

You can specify rke2 version with rke2_version variables. Refer to RKE2 supported version.

Upgrade by setting the target version via rke2_version and do_upgrade = true. It will upgrade the nodes one-by-one, server nodes first.

⚠️ In-place upgrade mechanism is not battle-tested and relies on Terraform provisioners.

Addons

Set the manifests_path variable to point out the directory containing your manifests and HelmChart (see JupyterHub example).

If you need a template step for your manifests, you can use manifests_gzb64 (see cinder-csi-plugin example).

⚠️ Modifications made to manifests after cluster deployement wont have any effect.

Downscale

You need to manually drain and remove node before downscaling a pool nodes.

Usage with Terraform Kubernetes Provider and Helm Provider

You can tell the module to output kubernetes config by setting output_kubernetes_config = true.

⚠️ Interpolating provider variables from module output is not the recommended way to achieve integration. See here and here.

Use of a data sources is recommended.

(Not recommended) You can use this module to populate Terraform Kubernetes Provider :

provider "kubernetes" {
  host     = module.controlplane.kubernetes_config.host
  client_certificate     = module.controlplane.kubernetes_config.client_certificate
  client_key             = module.controlplane.kubernetes_config.client_key
  cluster_ca_certificate = module.controlplane.kubernetes_config.cluster_ca_certificate
}

Recommended way needs two apply operations, and setting the proper terraform_remote_state data source :

provider "kubernetes" {
  host     = data.terraform_remote_state.rke2.outputs.kubernetes_config.host
  client_certificate     = data.terraform_remote_state.rke2.outputs.kubernetes_config.client_certificate
  client_key             = data.terraform_remote_state.rke2.outputs.kubernetes_config.client_key
  cluster_ca_certificate = data.terraform_remote_state.rke2.outputs.kubernetes_config.cluster_ca_certificate
}

Availability Zones

Changes to a module's availability_zones will intentionally not cause the recreation of instances. You must manually taint the module.controlplane.module.server.openstack_compute_instance_v2.instance for force the recreation of the resource.