Hetzner Cloud terraform coreos install

ignition.json

{
  "ignition": {
    "version": "2.0.0",
    "config": {}
  },
  "storage": {
  },
  "systemd": {},
  "networkd": {},
  "passwd": {
    "users": [
      {
        "name": "core",
        "sshAuthorizedKeys": [
          "<your public key>"
        ]
      }
    ]
  }
}

install.sh

#!/usr/bin/env sh

set -e

wget https://raw.github.com/coreos/init/master/bin/coreos-install
chmod +x coreos-install
./coreos-install -d /dev/sda -i /root/ignition.json
reboot

main.tf

provider "hcloud" {
  token = "<token>"
}

resource "hcloud_ssh_key" "notebook" {
  name = "nschieder@notebook"
  public_key = "${file("~/.ssh/id_ed25519.pub")}"
}

resource "hcloud_server" "master" {
  name = "master"
  image = "debian-9"
  server_type = "cx11"
  ssh_keys = ["${hcloud_ssh_key.notebook.id}"]
  datacenter = "fsn1-dc8"
  rescue = "linux64"

  connection {
    host = "${hcloud_server.master.ipv4_address}"
    timeout = "1m"
    agent = false
    private_key = "${file("~/.ssh/id_ed25519")}"
  }

  provisioner "file" {
    source      = "ignition.json"
    destination = "/root/ignition.json"
  }

  provisioner "remote-exec" {
    script = "install.sh"
  }

  provisioner "remote-exec" {
    connection {
      host = "${hcloud_server.master.ipv4_address}"
      timeout = "1m"
      agent = false
      private_key = "${file("~/.ssh/id_ed25519")}"
      user = "core"
    }
    inline = "sudo hostnamectl set-hostname ${hcloud_server.master.name}"
  }
}

resource "hcloud_server" "node1" {
  name = "node1"
  image = "debian-9"
  server_type = "cx11"
  ssh_keys = ["${hcloud_ssh_key.notebook.id}"]
  datacenter = "fsn1-dc8"
  rescue = "linux64"

  connection {
    host = "${hcloud_server.node1.ipv4_address}"
    timeout = "1m"
    agent = false
    private_key = "${file("~/.ssh/id_ed25519")}"
  }

  provisioner "file" {
    source      = "ignition.json"
    destination = "/root/ignition.json"
  }

  provisioner "remote-exec" {
    script = "install.sh"
  }

  provisioner "remote-exec" {
    connection {
      host = "${hcloud_server.node1.ipv4_address}"
      timeout = "1m"
      agent = false
      private_key = "${file("~/.ssh/id_ed25519")}"
      user = "core"
    }
    inline = "sudo hostnamectl set-hostname ${hcloud_server.node1.name}"
  }
}

@thetechnick How do you deal with attached volumes? Afaik the volume ID has to be referenced in the ignition.json, but a volume (or volume attachment) requires the server ID, which will only be available once the hcloud_server is provisioned, during which ignition.json is already consumed.
Also, because of the reboot at the end of the install script no exit code is returned, which causes tf to report an error.

@mootari Well I created these scripts before there was any Blockstorage support at Hetzner.

Currently I work exclusively with Kubernetes, so the Container Storage Interface takes care of volume attachment and management.

It should be quite straightforward to build something with the Terraform null and template resource, but I have no use for this right now.

@thetechnick Understood, thanks for offering some context (and thanks for this gist!). My current solution also uses null_resource, although properly tainting an existing server resource and applying changes is still a pain. Once I figure that part out I'll link a gist to it here.