Add support for Flatcar Linux bare-metal cached_install

* Support bare-metal cached_install=true mode with Flatcar Linux
where assets are fetched from the Matchbox assets cache instead
of from the upstream Flatcar download server
* Skipped in original Flatcar support to keep it simple
https://github.com/poseidon/typhoon/pull/209

CHANGES.md

@@ -20,6 +20,10 @@ Notable changes between versions.
 * Remove admin_password field (disabled) since it is now optional
   * Require `terraform-provider-azurerm` v1.16+ (action required)
 
+#### Bare-Metal
+
+* Add support for `cached_install` mode with Flatcar Linux ([#315](https://github.com/poseidon/typhoon/pull/315))
+
 #### DigitalOcean
 
 * Require `terraform-provider-digitalocean` v1.0+ (action required)

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

@@ -49,7 +49,7 @@ data "template_file" "container-linux-install-configs" {
 }
 
 // Container Linux Install profile (from matchbox /assets cache)
-// Note: Admin must have downloaded os_version into matchbox assets.
+// Note: Admin must have downloaded os_version into matchbox assets/coreos.
 resource "matchbox_profile" "cached-container-linux-install" {
   count = "${length(var.controller_names) + length(var.worker_names)}"
   name  = "${format("%s-cached-container-linux-install-%s", var.cluster_name, element(concat(var.controller_names, var.worker_names), count.index))}"
@@ -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/flatcar.
+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)}"

docs/cl/bare-metal.md

@@ -377,7 +377,7 @@ Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/bare-me
 
 | Name | Description | Default | Example |
 |:-----|:------------|:--------|:--------|
-| cached_install | Whether machines should PXE boot and install from the Matchbox `/assets` cache. Admin MUST have downloaded Container Linux images into the cache to use this (coreos only for now) | false | true |
+| cached_install | PXE boot and install from the Matchbox `/assets` cache. Admin MUST have downloaded Container Linux or Flatcar images into the cache | false | true |
 | install_disk | Disk device where Container Linux should be installed | "/dev/sda" | "/dev/sdb" |
 | networking | Choice of networking provider | "calico" | "calico" or "flannel" |
 | network_mtu | CNI interface MTU (calico-only) | 1480 | - |