fix: Use eu-central network zone, handle existing SSH key

terraform/network.tf

@@ -6,6 +6,6 @@ resource "hcloud_network" "cluster" {
 resource "hcloud_network_subnet" "servers" {
   network_id   = hcloud_network.cluster.id
   type         = "cloud"
-  network_zone = "${var.location}-network"
+  network_zone = "eu-central"
   ip_range     = var.subnet_cidr
 }

terraform/servers.tf

@@ -10,7 +10,7 @@ resource "hcloud_server" "control_plane" {
   server_type = var.control_plane_type
   image       = data.hcloud_image.ubuntu.id
   location    = var.location
-  ssh_keys    = [hcloud_ssh_key.cluster.id]
+  ssh_keys    = [data.hcloud_ssh_key.cluster.id]
 
   labels = {
     cluster = var.cluster_name
@@ -37,7 +37,7 @@ resource "hcloud_server" "workers" {
   server_type = var.worker_type
   image       = data.hcloud_image.ubuntu.id
   location    = var.location
-  ssh_keys    = [hcloud_ssh_key.cluster.id]
+  ssh_keys    = [data.hcloud_ssh_key.cluster.id]
 
   labels = {
     cluster = var.cluster_name

terraform/ssh.tf

@@ -2,7 +2,21 @@ data "local_file" "ssh_public_key" {
   filename = pathexpand(var.ssh_public_key)
 }
 
+data "hcloud_ssh_keys" "all_keys" {}
+
+locals {
+  existing_key = try([
+    for key in data.hcloud_ssh_keys.all_keys.ssh_keys :
+    key if key.name == "${var.cluster_name}-ssh-key"
+  ][0], null)
+}
+
 resource "hcloud_ssh_key" "cluster" {
+  count      = local.existing_key == null ? 1 : 0
   name       = "${var.cluster_name}-ssh-key"
   public_key = data.local_file.ssh_public_key.content
 }
+
+data "hcloud_ssh_key" "cluster" {
+  fingerprint = local.existing_key != null ? local.existing_key.fingerprint : hcloud_ssh_key.cluster[0].fingerprint
+}