cluster/k8s_flatcar_machines.tf

resource "null_resource" "worker-config" {
  triggers = {
    version = var.worker_k3s_version
  }
}

resource "tls_private_key" "provisioning" {
  algorithm = "RSA"
  rsa_bits  = 4096
}

resource "hcloud_ssh_key" "provisioning_key" {
  name       = "Provisioning key for hcloud cluster"
  public_key = tls_private_key.provisioning.public_key_openssh
}

resource "local_file" "provisioning_key" {
  filename             = "${path.module}/.ssh/provisioning_private_key.pem"
  content              = tls_private_key.provisioning.private_key_pem
  directory_permission = "0700"
  file_permission      = "0400"
}

resource "local_file" "provisioning_key_pub" {
  filename             = "${path.module}/.ssh/provisioning_key.pub"
  content              = tls_private_key.provisioning.public_key_openssh
  directory_permission = "0700"
  file_permission      = "0440"
}

resource "null_resource" "machine_generation" {
  for_each = var.k3s_workers
  triggers = {
    timestamp = "${each.value.generation}"
  }
}

resource "hcloud_placement_group" "k3s_machines" {
  name = "k3s-machines"
  type = "spread"
  labels = {
    "cluster" = "icb4dc0.de"
  }
}

resource "hcloud_server" "machine" {
  for_each           = var.k3s_workers
  name               = each.key
  server_type        = each.value.server_type
  location           = each.value.location
  image              = "ubuntu-22.04"
  placement_group_id = hcloud_placement_group.k3s_machines.id

  backups = false

  lifecycle {
    replace_triggered_by = [
      null_resource.worker-config,
      null_resource.machine_generation[each.key]
    ]
  }

  ssh_keys = [
    hcloud_ssh_key.provisioning_key.id,
    hcloud_ssh_key.default.id
  ]

  labels = {
    "node_type" = "worker"
    "cluster"   = "icb4dc0.de"
  }

  network {
    network_id = hcloud_network.k8s_net.id
    ip         = each.value.private_ip
  }

  public_net {
    ipv4_enabled = true
    ipv6_enabled = false
  }

  # boot into rescue OS
  rescue = "linux64"

  connection {
    host        = self.ipv4_address
    agent       = false
    private_key = tls_private_key.provisioning.private_key_pem
    timeout     = "5m"
  }

  provisioner "file" {
    source      = "${path.module}/configs/cp/traefik.yaml"
    destination = "/root/traefik.yaml"
  }

  provisioner "file" {
    content     = data.ct_config.machine-ignitions[each.key].rendered
    destination = "/root/ignition.json"
  }

  provisioner "remote-exec" {
    inline = [
      "set -ex",
      "apt-get install -y gawk",
      "curl -fsSLO --retry-delay 1 --retry 60 --retry-connrefused --retry-max-time 60 --connect-timeout 20 https://raw.githubusercontent.com/flatcar/init/flatcar-master/bin/flatcar-install",
      "chmod +x flatcar-install",
      "./flatcar-install -s -i /root/ignition.json -C ${var.flatcar_release_channel}",
      "reboot",
    ]
    on_failure = continue
  }

  provisioner "remote-exec" {
    connection {
      host        = self.ipv4_address
      private_key = tls_private_key.provisioning.private_key_pem
      timeout     = "3m"
      user        = "core"
    }
    inline = [
      "sudo hostnamectl set-hostname ${self.name}",
    ]
  }

}

resource "null_resource" "machine-drainable" {
  for_each = var.k3s_workers

  lifecycle {
    replace_triggered_by = [hcloud_server.machine[each.key]]
  }

  provisioner "local-exec" {
    when       = destroy
    on_failure = continue
    command    = "kubectl drain --delete-emptydir-data=true --ignore-daemonsets=true --disable-eviction ${each.key}"
  }
}

data "ct_config" "machine-ignitions" {
  for_each = var.k3s_workers
  strict   = true
  content = templatefile(
    "${path.module}/configs/workers/k3s-flatcar.yaml",
    {
      "host"         = "${each.key}"
      "k3s_token"    = "${var.k3s_token}"
      "node_ip"      = "${each.value.private_ip}"
      "k3s_version"  = "${var.worker_k3s_version}"
      "storage_node" = each.value.storage_node
    }
  )
  snippets = [
    templatefile(
      "${path.module}/configs/core-user.yaml.tmpl",
      {
        ssh_keys = jsonencode(concat(var.ssh_keys, [tls_private_key.provisioning.public_key_openssh]))
      }
    )
  ]
}