Add temporary variables for multi-nic testing

* Accept ordered lists of controller and worker networkd configs
* Do not rely on these variables. They will be replaced with a
cleaner mechanism at a future date

bare-metal/container-linux/kubernetes/cl/controller.yaml.tmpl

@@ -172,6 +172,8 @@ storage:
             --net=host \
             --dns=host \
             --exec=/bootkube -- start --asset-dir=/assets "$@"
+networkd:
+  ${networkd_content}
 passwd:
   users:
     - name: core

bare-metal/container-linux/kubernetes/cl/worker.yaml.tmpl

@@ -108,6 +108,8 @@ storage:
       contents:
         inline: |
           fs.inotify.max_user_watches=16184
+networkd:
+  ${networkd_content}
 passwd:
   users:
     - name: core

bare-metal/container-linux/kubernetes/profiles.tf

@@ -87,6 +87,7 @@ data "template_file" "controller-configs" {
     etcd_initial_cluster = "${join(",", formatlist("%s=https://%s:2380", var.controller_names, var.controller_domains))}"
     k8s_dns_service_ip   = "${module.bootkube.kube_dns_service_ip}"
     ssh_authorized_key   = "${var.ssh_authorized_key}"
+    networkd_content = "${element(var.controller_networkds, count.index)}"
   }
 }
 
@@ -106,5 +107,6 @@ data "template_file" "worker-configs" {
     domain_name        = "${element(var.worker_domains, count.index)}"
     k8s_dns_service_ip = "${module.bootkube.kube_dns_service_ip}"
     ssh_authorized_key = "${var.ssh_authorized_key}"
+    networkd_content = "${element(var.worker_networkds, count.index)}"
   }
 }

bare-metal/container-linux/kubernetes/variables.tf

@@ -111,7 +111,22 @@ variable "container_linux_oem" {
 }
 
 variable "kernel_args" {
-  description = "Additional kernel arguments the servers should boot with."
+  description = "Additional kernel arguments to provide at PXE boot."
   type        = "list"
   default     = []
 }
+
+# unofficial, undocumented, unsupported, temporary
+
+variable "controller_networkds" {
+  type = "list"
+  description = "Controller Container Linux config networkd section"
+  default = []
+}
+
+variable "worker_networkds" {
+  type = "list"
+  description = "Worker Container Linux config networkd section"
+  default = []
+}
+

bare-metal/container-linux/pxe-worker/variables.tf

@@ -57,9 +57,8 @@ variable "kube_dns_service_ip" {
 # optional
 
 variable "kernel_args" {
-  description = "Additional kernel arguments the server should boot with."
+  description = "Additional kernel arguments to provide at PXE boot."
   type        = "list"
-
   default = [
     "root=/dev/sda1",
   ]