Add support for Flatcar Linux on Azure

* Accept `os_image` "flatcar-stable" and "flatcar-beta" to
use Kinvolk's Flatcar Linux images from the Azure Marketplace

Note: Flatcar Linux Azure Marketplace images require terms be
accepted before use

CHANGES.md

@@ -21,6 +21,8 @@ Notable changes between versions.
   * Switch to Azure's new Linux VM and Linux VM Scale Set resources
   * Set controller's Azure disk caching to None
   * Associate subnets (in addition to NICs) with security groups (aesthetic)
+* Add support for Flatcar Container Linux ([#664](https://github.com/poseidon/typhoon/pull/664))
+  * Requires accepting Flatcar Linux Azure Marketplace terms
 
 #### Bare-Metal
 

README.md

@@ -42,6 +42,7 @@ Typhoon is available for [Flatcar Container Linux](https://www.flatcar-linux.org
 | Platform      | Operating System | Terraform Module | Status |
 |---------------|------------------|------------------|--------|
 | AWS           | Flatcar Linux    | [aws/container-linux/kubernetes](aws/container-linux/kubernetes) | stable |
+| Azure         | Flatcar Linux    | [azure/container-linux/kubernetes](azure/container-linux/kubernetes) | alpha |
 | Bare-Metal    | Flatcar Linux    | [bare-metal/container-linux/kubernetes](bare-metal/container-linux/kubernetes) | stable |
 | Google Cloud  | Flatcar Linux  | [google-cloud/container-linux/kubernetes](google-cloud/container-linux/kubernetes) | alpha |
 | Digital Ocean | Flatcar Linux  | [digital-ocean/container-linux/kubernetes](digital-ocean/container-linux/kubernetes) | alpha |

azure/container-linux/kubernetes/controllers.tf

@@ -15,8 +15,10 @@ resource "azurerm_dns_a_record" "etcds" {
 }
 
 locals {
-  # Channel for a Container Linux derivative
+  # Container Linux derivative
   # coreos-stable -> Container Linux Stable
+  # flatcar-stable -> Flatcar Linux Stable
+  flavor  = split("-", var.os_image)[0]
   channel = split("-", var.os_image)[1]
 }
 
@@ -52,12 +54,23 @@ resource "azurerm_linux_virtual_machine" "controllers" {
   }
 
   source_image_reference {
-    publisher = "CoreOS"
+    publisher = local.flavor == "flatcar" ? "Kinvolk" : "CoreOS"
-    offer     = "CoreOS"
+    offer     = local.flavor == "flatcar" ? "flatcar-container-linux" : "CoreOS"
     sku       = local.channel
     version   = "latest"
   }
 
+  # Gross hack just for Flatcar Linux
+  dynamic "plan" {
+    for_each = local.flavor == "flatcar" ? [1] : []
+
+    content {
+      name = local.channel
+      publisher = "kinvolk"
+      product = "flatcar-container-linux"
+    }
+  }
+
   # network
   network_interface_ids = [
     azurerm_network_interface.controllers.*.id[count.index]

azure/container-linux/kubernetes/variables.tf

@@ -49,7 +49,7 @@ variable "worker_type" {
 variable "os_image" {
   type        = string
   default     = "coreos-stable"
-  description = "Channel for a Container Linux derivative (coreos-stable, coreos-beta, coreos-alpha)"
+  description = "Channel for a Container Linux derivative (coreos-stable, coreos-beta, coreos-alpha, flatcar-stable, flatcar-beta)"
 }
 
 variable "disk_size" {

azure/container-linux/kubernetes/workers/workers.tf

@@ -1,6 +1,7 @@
 locals {
-  # Channel for a Container Linux derivative
   # coreos-stable -> Container Linux Stable
+  # flatcar-stable -> Flatcar Linux Stable
+  flavor  = split("-", var.os_image)[0]
   channel = split("-", var.os_image)[1]
 }
 
@@ -24,12 +25,23 @@ resource "azurerm_linux_virtual_machine_scale_set" "workers" {
   }
 
   source_image_reference {
-    publisher = "CoreOS"
+    publisher = local.flavor == "flatcar" ? "Kinvolk" : "CoreOS"
-    offer     = "CoreOS"
+    offer     = local.flavor == "flatcar" ? "flatcar-container-linux" : "CoreOS"
     sku       = local.channel
     version   = "latest"
   }
 
+  # Gross hack just for Flatcar Linux
+  dynamic "plan" {
+    for_each = local.flavor == "flatcar" ? [1] : []
+
+    content {
+      name = local.channel
+      publisher = "kinvolk"
+      product = "flatcar-container-linux"
+    }
+  }
+
   # Azure requires setting admin_ssh_key, though Ignition custom_data handles it too
   admin_username = "core"
   admin_ssh_key {

docs/cl/azure.md

@@ -85,6 +85,15 @@ module "ramius" {
 
 Reference the [variables docs](#variables) or the [variables.tf](https://github.com/poseidon/typhoon/blob/master/azure/container-linux/kubernetes/variables.tf) source.
 
+### Flatcar Linux Only
+
+Flatcar Linux publishes images to the Azure Marketplace and requires accepting their legal terms.
+
+```
+az vm image terms show --publish kinvolk --offer flatcar-container-linux --plan stable
+az vm image terms accept --publish kinvolk --offer flatcar-container-linux --plan stable
+```
+
 ## ssh-agent
 
 Initial bootstrapping requires `bootstrap.service` be started on one controller node. Terraform uses `ssh-agent` to automate this step. Add your SSH private key to `ssh-agent`.
@@ -223,7 +232,7 @@ Reference the DNS zone with `azurerm_dns_zone.clusters.name` and its resource gr
 | worker_count | Number of workers | 1 | 3 |
 | controller_type | Machine type for controllers | "Standard_B2s" | See below |
 | worker_type | Machine type for workers | "Standard_DS1_v2" | See below |
-| os_image | Channel for a Container Linux derivative | "coreos-stable" | coreos-stable, coreos-beta, coreos-alpha |
+| os_image | Channel for a Container Linux derivative | "coreos-stable" | coreos-stable, coreos-beta, coreos-alpha, flatcar-stable, flatcar-beta |
 | disk_size | Size of the disk in GB | 40 | 100 |
 | worker_priority | Set priority to Spot to use reduced cost surplus capacity, with the tradeoff that instances can be deallocated at any time | Regular | Spot |
 | controller_clc_snippets | Controller Container Linux Config snippets | [] | [example](/advanced/customization/#usage) |

docs/index.md

@@ -42,6 +42,7 @@ Typhoon is available for [Flatcar Container Linux](https://www.flatcar-linux.org
 | Platform      | Operating System | Terraform Module | Status |
 |---------------|------------------|------------------|--------|
 | AWS           | Flatcar Linux    | [aws/container-linux/kubernetes](cl/aws.md) | stable |
+| Azure         | Flatcar Linux    | [azure/container-linux/kubernetes](cl/azure.md) | alpha |
 | Bare-Metal    | Flatcar Linux    | [bare-metal/container-linux/kubernetes](cl/bare-metal.md) | stable |
 | Google Cloud  | Flatcar Linux  | [google-cloud/container-linux/kubernetes](cl/google-cloud.md) | alpha |
 | Digital Ocean | Flatcar Linux  | [digital-ocean/container-linux/kubernetes](cl/digital-ocean.md) | alpha |