Add support for ephemeral hosts

hosts.auto.tfvars

@@ -23,4 +23,13 @@ hosts = {
     server_type = "cx32"
     datacenter = "fsn1-dc14"
   },
+  #"node004" = {
+  #  hostname = "node004"
+  #  rdns = "node004.serguzim.net"
+  #  provider = "hetzner"
+  #  ephemeral = true
+  #  image = "debian-12"
+  #  server_type = "cpx62"
+  #  datacenter = "fsn1-dc14"
+  #},
 }

modules/infrastructure/hcloud.tf

@@ -35,8 +35,9 @@ resource "hcloud_server" "nodes" {
   server_type = each.value.server_type
   ssh_keys    = [hcloud_ssh_key.default.id]
   user_data   = templatefile("./templates/cloud-init.yaml.tpl", {
-    tailscale_authkey = tailscale_tailnet_key.cloud_init_key.key,
+    tailscale_authkey = each.value.ephemeral ? tailscale_tailnet_key.cloud_init_ephemeral_key.key : tailscale_tailnet_key.cloud_init_key.key,
     default_ssh_key   = var.default_ssh_key.public_key
+    hostname          = each.value.hostname
   })
   placement_group_id = hcloud_placement_group.default.id
   public_net {

modules/infrastructure/tailscale.tf

@@ -5,6 +5,13 @@ resource "tailscale_tailnet_key" "cloud_init_key" {
   expiry        = 21600 # 6 hours
   description   = "Cloud-init key used by opentofu"
 }
+resource "tailscale_tailnet_key" "cloud_init_ephemeral_key" {
+  reusable      = true
+  ephemeral     = true
+  preauthorized = true
+  expiry        = 21600 # 6 hours
+  description   = "Ephemeral cloud-init key used by opentofu"
+}
 
 resource "time_sleep" "wait_for_hosts" {
   for_each = var.hosts

modules/infrastructure/variables.tf

@@ -46,6 +46,7 @@ variable "hosts" {
     hostname = string
     rdns = string
     provider = string
+    ephemeral = optional(bool, false)
     image = optional(string)
     server_type = optional(string)
     datacenter = optional(string)

templates/cloud-init.yaml.tpl

@@ -36,5 +36,5 @@ runcmd:
   #####################################################################
   # One-command install, from https://tailscale.com/download/
   - ['sh', '-c', 'curl -fsSL https://tailscale.com/install.sh | sh']
-  - ['tailscale', 'up', '--authkey=${tailscale_authkey}']
+  - ['tailscale', 'up', '--authkey=${tailscale_authkey}', '--hostname=${hostname}']
 

variables.tf

@@ -183,6 +183,7 @@ variable "hosts" {
     hostname = string
     rdns = string
     provider = string
+    ephemeral = optional(bool, false)
     image = optional(string)
     server_type = optional(string)
     datacenter = optional(string)