use 'lucidsolns/ct' instead of 'poseidon/ct' provider and add support…

… for butane local files

- the poseidon ct provider doesn't set the `FilesDir` option which means the whole of the butane configuration has to be in one file (unless using a remote source)
- this is likely to be switched back to 'poseidon/ct' when the pull request is merged

see:

  - poseidon/terraform-provider-ct#175

main.tf

@@ -28,8 +28,8 @@ terraform {
         - https://www.flatcar.org/docs/latest/provisioning/config-transpiler/
     */
     ct = {
-      source  = "poseidon/ct"
-      version = ">= 0.13.0"
+      source  = "lucidsolns/ct"
+      version = ">= 0.13.1"
     }
 
     /*
@@ -321,6 +321,7 @@ data "ct_config" "ignition_json" {
   })
   strict       = true
   pretty_print = false
+  files_dir = var.butane_path
 
   snippets = [
     for snippet in var.butane_conf_snippets : templatefile(var.butane_conf, {

variables.tf

@@ -283,3 +283,18 @@ variable "startup" {
   type        = string
   default     = "order=any"
 }
+
+variable butane_path {
+  description = <<-EOF
+     The path used to allow embedding local files.module
+
+     If this is set then the use of local files is enabled: e.g. in the butane files section:
+
+         - path: /etc/docker-compose.yaml
+           contents:
+             local: docker-compose.yaml
+
+  EOF
+  type    = string
+  default = null
+}