bare-metal: support cached install for Flatcar

Add support for the "cached install" variant (assets are fetched from
matchbox and not the upstream server) for Flatcar.

Also, remove a hardcoded `coreos` in a few places and use
`${os_flavor}` instead to make the code work for both Container Linux
and Flatcar based installs.

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

@@ -81,7 +81,7 @@ systemd:
         ExecStartPre=/bin/mkdir -p /var/lib/kubelet/volumeplugins
         ExecStartPre=/usr/bin/bash -c "grep 'certificate-authority-data' /etc/kubernetes/kubeconfig | awk '{print $2}' | base64 -d > /etc/kubernetes/ca.crt"
         ExecStartPre=-/usr/bin/rkt rm --uuid-file=/var/cache/kubelet-pod.uuid
-        ExecStart=/usr/lib/coreos/kubelet-wrapper \
+        ExecStart=/usr/lib/${os_flavor}/kubelet-wrapper \
           --anonymous-auth=false \
           --authentication-token-webhook \
           --authorization-mode=Webhook \

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

@@ -54,7 +54,7 @@ systemd:
         ExecStartPre=/bin/mkdir -p /var/lib/kubelet/volumeplugins
         ExecStartPre=/usr/bin/bash -c "grep 'certificate-authority-data' /etc/kubernetes/kubeconfig | awk '{print $2}' | base64 -d > /etc/kubernetes/ca.crt"
         ExecStartPre=-/usr/bin/rkt rm --uuid-file=/var/cache/kubelet-pod.uuid
-        ExecStart=/usr/lib/coreos/kubelet-wrapper \
+        ExecStart=/usr/lib/${os_flavor}/kubelet-wrapper \
           --anonymous-auth=false \
           --authentication-token-webhook \
           --authorization-mode=Webhook \

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

@@ -3,7 +3,7 @@ resource "matchbox_group" "install" {
 
   name = "${format("install-%s", element(concat(var.controller_names, var.worker_names), count.index))}"
 
-  profile = "${local.flavor == "flatcar" ? element(matchbox_profile.flatcar-install.*.name, count.index) : var.cached_install == "true" ? element(matchbox_profile.cached-container-linux-install.*.name, count.index) : element(matchbox_profile.container-linux-install.*.name, count.index)}"
+  profile = "${local.flavor == "flatcar" ? var.cached_install == "true" ? element(matchbox_profile.cached-flatcar-linux-install.*.name, count.index) : element(matchbox_profile.flatcar-install.*.name, count.index) : var.cached_install == "true" ? element(matchbox_profile.cached-container-linux-install.*.name, count.index) : element(matchbox_profile.container-linux-install.*.name, count.index)}"
 
   selector {
     mac = "${element(concat(var.controller_macs, var.worker_macs), count.index)}"

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

@@ -87,7 +87,7 @@ data "template_file" "cached-container-linux-install-configs" {
     ssh_authorized_key  = "${var.ssh_authorized_key}"
 
     # profile uses -b baseurl to install from matchbox cache
-    baseurl_flag = "-b ${var.matchbox_http_endpoint}/assets/coreos"
+    baseurl_flag = "-b ${var.matchbox_http_endpoint}/assets/${local.flavor}"
   }
 }
 
@@ -114,6 +114,30 @@ resource "matchbox_profile" "flatcar-install" {
   container_linux_config = "${element(data.template_file.container-linux-install-configs.*.rendered, count.index)}"
 }
 
+// Flatcar Linux Install profile (from matchbox /assets cache)
+// Note: Admin must have downloaded os_version into matchbox assets.
+resource "matchbox_profile" "cached-flatcar-linux-install" {
+  count = "${length(var.controller_names) + length(var.worker_names)}"
+  name  = "${format("%s-cached-flatcar-linux-install-%s", var.cluster_name, element(concat(var.controller_names, var.worker_names), count.index))}"
+
+  kernel = "/assets/flatcar/${var.os_version}/flatcar_production_pxe.vmlinuz"
+
+  initrd = [
+    "/assets/flatcar/${var.os_version}/flatcar_production_pxe_image.cpio.gz",
+  ]
+
+  args = [
+    "initrd=flatcar_production_pxe_image.cpio.gz",
+    "flatcar.config.url=${var.matchbox_http_endpoint}/ignition?uuid=$${uuid}&mac=$${mac:hexhyp}",
+    "flatcar.first_boot=yes",
+    "console=tty0",
+    "console=ttyS0",
+    "${var.kernel_args}",
+  ]
+
+  container_linux_config = "${element(data.template_file.cached-container-linux-install-configs.*.rendered, count.index)}"
+}
+
 // Kubernetes Controller profiles
 resource "matchbox_profile" "controllers" {
   count        = "${length(var.controller_names)}"
@@ -136,6 +160,7 @@ data "template_file" "controller-configs" {
   template = "${file("${path.module}/cl/controller.yaml.tmpl")}"
 
   vars {
+    os_flavor             = "${local.flavor}"
     domain_name           = "${element(var.controller_domains, count.index)}"
     etcd_name             = "${element(var.controller_names, count.index)}"
     etcd_initial_cluster  = "${join(",", formatlist("%s=https://%s:2380", var.controller_names, var.controller_domains))}"
@@ -167,6 +192,7 @@ data "template_file" "worker-configs" {
   template = "${file("${path.module}/cl/worker.yaml.tmpl")}"
 
   vars {
+    os_flavor             = "${local.flavor}"
     domain_name           = "${element(var.worker_domains, count.index)}"
     k8s_dns_service_ip    = "${module.bootkube.kube_dns_service_ip}"
     cluster_domain_suffix = "${var.cluster_domain_suffix}"