Migrate bare-metal module Terraform v0.11 to v0.12

* Replace v0.11 bracket type hints with Terraform v0.12 list expressions
* Use expression syntax instead of interpolated strings, where suggested
* Update bare-metal tutorial
* Define `clc_snippets` type constraint map(list(string))
* Define Terraform and plugin version requirements in versions.tf
  * Require matchbox ~> 0.3.0 to support Terraform v0.12
  * Require ct ~> 0.3.2 to support Terraform v0.12

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

@@ -1,22 +1,22 @@
 variable "cluster_name" {
-  type        = "string"
+  type        = string
   description = "Unique cluster name"
 }
 
 # bare-metal
 
 variable "matchbox_http_endpoint" {
-  type        = "string"
+  type        = string
   description = "Matchbox HTTP read-only endpoint (e.g. http://matchbox.example.com:8080)"
 }
 
 variable "os_channel" {
-  type        = "string"
+  type        = string
   description = "Channel for a Container Linux derivative (coreos-stable, coreos-beta, coreos-alpha, flatcar-stable, flatcar-beta, flatcar-alpha)"
 }
 
 variable "os_version" {
-  type        = "string"
+  type        = string
   description = "Version for a Container Linux derivative to PXE and install (coreos-stable, coreos-beta, coreos-alpha, flatcar-stable, flatcar-beta, flatcar-alpha)"
 }
 
@@ -24,37 +24,37 @@ variable "os_version" {
 # Terraform's crude "type system" does not properly support lists of maps so we do this.
 
 variable "controller_names" {
-  type        = "list"
+  type        = list(string)
   description = "Ordered list of controller names (e.g. [node1])"
 }
 
 variable "controller_macs" {
-  type        = "list"
+  type        = list(string)
   description = "Ordered list of controller identifying MAC addresses (e.g. [52:54:00:a1:9c:ae])"
 }
 
 variable "controller_domains" {
-  type        = "list"
+  type        = list(string)
   description = "Ordered list of controller FQDNs (e.g. [node1.example.com])"
 }
 
 variable "worker_names" {
-  type        = "list"
+  type        = list(string)
   description = "Ordered list of worker names (e.g. [node2, node3])"
 }
 
 variable "worker_macs" {
-  type        = "list"
+  type        = list(string)
   description = "Ordered list of worker identifying MAC addresses (e.g. [52:54:00:b2:2f:86, 52:54:00:c3:61:77])"
 }
 
 variable "worker_domains" {
-  type        = "list"
+  type        = list(string)
   description = "Ordered list of worker FQDNs (e.g. [node2.example.com, node3.example.com])"
 }
 
 variable "clc_snippets" {
-  type        = "map"
+  type        = map(list(string))
   description = "Map from machine names to lists of Container Linux Config snippets"
   default     = {}
 }
@@ -63,40 +63,40 @@ variable "clc_snippets" {
 
 variable "k8s_domain_name" {
   description = "Controller DNS name which resolves to a controller instance. Workers and kubeconfig's will communicate with this endpoint (e.g. cluster.example.com)"
-  type        = "string"
+  type        = string
 }
 
 variable "ssh_authorized_key" {
-  type        = "string"
+  type        = string
   description = "SSH public key for user 'core'"
 }
 
 variable "asset_dir" {
   description = "Path to a directory where generated assets should be placed (contains secrets)"
-  type        = "string"
+  type        = string
 }
 
 variable "networking" {
   description = "Choice of networking provider (flannel or calico)"
-  type        = "string"
+  type        = string
   default     = "calico"
 }
 
 variable "network_mtu" {
   description = "CNI interface MTU (applies to calico only)"
-  type        = "string"
+  type        = string
   default     = "1480"
 }
 
 variable "network_ip_autodetection_method" {
   description = "Method to autodetect the host IPv4 address (applies to calico only)"
-  type        = "string"
+  type        = string
   default     = "first-found"
 }
 
 variable "pod_cidr" {
   description = "CIDR IPv4 range to assign Kubernetes pods"
-  type        = "string"
+  type        = string
   default     = "10.2.0.0/16"
 }
 
@@ -106,7 +106,8 @@ CIDR IPv4 range to assign Kubernetes services.
 The 1st IP will be reserved for kube_apiserver, the 10th IP will be reserved for coredns.
 EOD
 
-  type    = "string"
+
+  type = string
   default = "10.3.0.0/16"
 }
 
@@ -114,48 +115,49 @@ EOD
 
 variable "cluster_domain_suffix" {
   description = "Queries for domains with the suffix will be answered by coredns. Default is cluster.local (e.g. foo.default.svc.cluster.local) "
-  type        = "string"
-  default     = "cluster.local"
+  type = string
+  default = "cluster.local"
 }
 
 variable "download_protocol" {
-  type        = "string"
-  default     = "https"
+  type = string
+  default = "https"
   description = "Protocol iPXE should use to download the kernel and initrd. Defaults to https, which requires iPXE compiled with crypto support. Unused if cached_install is true."
 }
 
 variable "cached_install" {
-  type        = "string"
-  default     = "false"
+  type = string
+  default = "false"
   description = "Whether Container Linux should PXE boot and install from matchbox /assets cache. Note that the admin must have downloaded the os_version into matchbox assets."
 }
 
 variable "install_disk" {
-  type        = "string"
-  default     = "/dev/sda"
+  type = string
+  default = "/dev/sda"
   description = "Disk device to which the install profiles should install Container Linux (e.g. /dev/sda)"
 }
 
 variable "container_linux_oem" {
-  type        = "string"
-  default     = ""
+  type = string
+  default = ""
   description = "DEPRECATED: Specify an OEM image id to use as base for the installation (e.g. ami, vmware_raw, xen) or leave blank for the default image"
 }
 
 variable "kernel_args" {
   description = "Additional kernel arguments to provide at PXE boot."
-  type        = "list"
-  default     = []
+  type = list(string)
+  default = []
 }
 
 variable "enable_reporting" {
-  type        = "string"
+  type = string
   description = "Enable usage or analytics reporting to upstreams (Calico)"
-  default     = "false"
+  default = "false"
 }
 
 variable "enable_aggregation" {
   description = "Enable the Kubernetes Aggregation Layer (defaults to false)"
-  type        = "string"
-  default     = "false"
+  type = string
+  default = "false"
 }
+