Terraform snippets for Flatcar on Hetzner Cloud

flatcar-hetzner.tf

variable "worker_names" {
  type = "list"
}

#   worker_names = [
#    "w1",
#    "w2",
#    "w3",
#  ]

variable "hcloud_ssh_keys_names" {
  type = "list"
}

#  hcloud_ssh_keys_names = [
#    "[email protected]",
#    "[email protected]",
#  ]

variable "ssh_authorized_keys" {
  type = "list"
}

#  ssh_authorized_keys = [
#    "ssh-rsa AAA... [email protected]",
#    "ssh-rsa ABC... [email protected]",
#  ]

variable "worker_clc_snippets" {
  type        = "list"
  description = "Worker Container Linux Config snippets"
  default     = []
}

variable "worker_networkds" {
  type        = "list"
  description = "Worker Container Linux config networkd section"
  default     = []
}


data "template_file" "worker_config" {
  count = "${length(var.worker_names)}"
  template = "${file("${path.module}/cl/worker.yaml.tmpl")}"

  vars = {
    domain_name             = "${element(var.worker_domains, count.index)}"
    ssh_authorized_keys     = "${jsonencode(var.ssh_authorized_keys)}"

    # Terraform evaluates both sides regardless and element cannot be used on 0 length lists
    networkd_content = "${length(var.worker_networkds) == 0 ? "" : element(concat(var.worker_networkds, list("")), count.index)}"
  }
}


data "ct_config" "worker_ign" {
  count = "${length(var.worker_names)}"
  content      = "${element(data.template_file.worker_config.*.rendered, count.index)}"
  pretty_print = false
  snippets     = ["${var.worker_clc_snippets}"]
}

resource "hcloud_server" "workers" {
  count = "${length(var.worker_names)}"

  name = "${format("worker-%s", element(var.worker_names, count.index))}"
  image = "debian-9"
  server_type = "cx11"
  ssh_keys = "${var.hcloud_ssh_keys_names}"
  datacenter = "fsn1-dc8"
  rescue = "linux64"

  connection {
    host = "${self.ipv4_address}"
    timeout = "1m"
  }

  provisioner "file" {
    content = "${element(data.ct_config.worker_ign.*.rendered, count.index)}"
    destination = "/root/ignition.json"
  }

  provisioner "remote-exec" {
    script = "${path.module}/install-flatcar.bash"
  }

  provisioner "remote-exec" {
    connection {
      host = "${self.ipv4_address}"
      timeout = "2m"
      user = "core"
    }

    inline = "sudo hostnamectl set-hostname ${element(var.worker_names, count.index)}"
  }
}

install-flatcar.bash

#!/bin/bash

set -ex

curl -fsSLO https://raw.githubusercontent.com/flatcar-linux/init/flatcar-master/bin/flatcar-install
chmod +x flatcar-install
./flatcar-install -d /dev/sda -i /root/ignition.json
reboot

worker.yaml.tmpl

---
systemd:
  units:

storage:
  files:
    - path: /etc/hostname
      filesystem: root
      mode: 0644
      contents:
        inline:
          ${domain_name}

networkd:
  ${networkd_content}

passwd:
  users:
    - name: core
      ssh_authorized_keys: ${ssh_authorized_keys}