use yamlencode for k3s configs...

...and remove the now, hopefully unneeded workaround for
agent.conf, all values are in config.yaml now

agents.tf

@@ -59,27 +59,15 @@ resource "hcloud_server" "agents" {
     EOT
   }
 
-  # Generating and uploading the angent.conf file
-  provisioner "file" {
-    content = templatefile("${path.module}/templates/agent.conf.tpl", {
-      server_url = "https://${local.first_control_plane_network_ip}:6443"
-      node_token = random_password.k3s_token.result
-    })
-    destination = "/etc/rancher/k3s/agent.conf"
-
-    connection {
-      user           = "root"
-      private_key    = local.ssh_private_key
-      agent_identity = local.ssh_identity
-      host           = self.ipv4_address
-    }
-  }
-
   # Generating k3s server config file
   provisioner "file" {
-    content = templatefile("${path.module}/templates/agent_config.yaml.tpl", {
-      node_ip   = cidrhost(hcloud_network.k3s.ip_range, 2 + var.servers_num + count.index)
-      node_name = self.name
+    content = yamlencode({
+      node-name     = self.name
+      server        = "https://${local.first_control_plane_network_ip}:6443"
+      kubelet-arg   = "cloud-provider=external"
+      flannel-iface = "eth1"
+      node-ip       = local.first_control_plane_network_ip
+      token         = random_password.k3s_token.result
     })
     destination = "/etc/rancher/k3s/config.yaml"