Build AMIs on temporary EC2 builders

variables.tf

@@ -7,22 +7,18 @@ variable "aws_region" {
 variable "name" {
   type        = string
   default     = "nixos-zfs-ec2"
-  description = "Name prefix for the published AMI."
+  description = "Name prefix for builder resources and the published AMI."
 }
 
-variable "architecture" {
+variable "system" {
   type        = string
-  description = "AMI architecture, such as arm64 or x86_64."
-}
+  default     = "aarch64-linux"
+  description = "Target NixOS system for the AMI."
 
-variable "root_snapshot_id" {
-  type        = string
-  description = "Snapshot ID for the bootable NixOS root volume."
-}
-
-variable "nix_snapshot_id" {
-  type        = string
-  description = "Snapshot ID for the preseeded ZFS /nix volume."
+  validation {
+    condition     = contains(["aarch64-linux", "x86_64-linux"], var.system)
+    error_message = "system must be aarch64-linux or x86_64-linux."
+  }
 }
 
 variable "input_hash" {
@@ -40,32 +36,68 @@ variable "flake_lock_rev" {
   description = "Revision or hash representing flake.lock inputs."
 }
 
-variable "nixos_system_closure" {
+variable "builder_instance_type" {
   type        = string
-  default     = ""
-  description = "NixOS system closure path used to build the root image."
+  default     = "t4g.large"
+  description = "Temporary EC2 instance type used to build and seed the AMI."
 }
 
-variable "root_device_name" {
+variable "vpc_id" {
   type        = string
-  default     = "/dev/xvda"
-  description = "Root block device name used for AMI registration."
+  default     = null
+  description = "VPC ID. Defaults to the account default VPC."
 }
 
-variable "nix_device_name" {
+variable "subnet_id" {
   type        = string
-  default     = "/dev/sdf"
-  description = "AMI block device name for the /nix EBS snapshot. Runtime imports by ZFS pool identity, not this device name."
+  default     = null
+  description = "Subnet ID. Defaults to the first subnet in the selected/default VPC."
+}
+
+variable "base_nixos_ami_id" {
+  type        = string
+  default     = null
+  description = "Base NixOS AMI used only for the temporary builder. If null, OpenTofu searches for a recent NixOS AMI."
+}
+
+variable "base_nixos_ami_owners" {
+  type        = list(string)
+  default     = ["427812963091"]
+  description = "AWS account IDs to search for base NixOS AMIs."
+}
+
+variable "base_nixos_ami_name_pattern" {
+  type        = string
+  default     = null
+  description = "Base NixOS AMI name filter."
 }
 
 variable "root_volume_size_gb" {
   type        = number
   default     = 30
-  description = "Root EBS volume size."
+  description = "Temporary builder root EBS volume size. This becomes the final AMI root snapshot size."
 }
 
 variable "nix_volume_size_gb" {
   type        = number
   default     = 50
-  description = "/nix EBS volume size."
+  description = "Temporary /nix EBS volume size. This becomes the final AMI /nix snapshot size."
+}
+
+variable "nix_pool" {
+  type        = string
+  default     = "nixos-zfs-nix"
+  description = "ZFS pool name for the AMI-provided /nix volume."
+}
+
+variable "nix_device_name" {
+  type        = string
+  default     = "/dev/sdf"
+  description = "EC2 block device name for the AMI /nix volume. NixOS imports by ZFS pool identity, not this device name."
+}
+
+variable "ssh_public_key" {
+  type        = string
+  default     = null
+  description = "Optional SSH public key for debugging the temporary builder."
 }