nixos/virtualisation/linode-image: init (#155426)

nixos/modules/virtualisation/linode-image.nix

@@ -0,0 +1,66 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+let
+  cfg = config.virtualisation.linodeImage;
+  defaultConfigFile = pkgs.writeText "configuration.nix" ''
+    _: {
+      imports = [
+        <nixpkgs/nixos/modules/virtualisation/linode-image.nix>
+      ];
+    }
+  '';
+in
+{
+  imports = [ ./linode-config.nix ];
+
+  options = {
+    virtualisation.linodeImage.diskSize = mkOption {
+      type = with types; either (enum (singleton "auto")) ints.positive;
+      default = "auto";
+      example = 1536;
+      description = ''
+        Size of disk image in MB.
+      '';
+    };
+
+    virtualisation.linodeImage.configFile = mkOption {
+      type = with types; nullOr str;
+      default = null;
+      description = ''
+        A path to a configuration file which will be placed at `/etc/nixos/configuration.nix`
+        and be used when switching to a new configuration.
+        If set to `null`, a default configuration is used, where the only import is
+        `<nixpkgs/nixos/modules/virtualisation/linode-image.nix>`
+      '';
+    };
+
+    virtualisation.linodeImage.compressionLevel = mkOption {
+      type = types.ints.between 1 9;
+      default = 6;
+      description = ''
+        GZIP compression level of the resulting disk image (1-9).
+      '';
+    };
+  };
+
+  config = {
+    system.build.linodeImage = import ../../lib/make-disk-image.nix {
+      name = "linode-image";
+      # NOTE: Linode specifically requires images to be `gzip`-ed prior to upload
+      # See: https://www.linode.com/docs/products/tools/images/guides/upload-an-image/#requirements-and-considerations
+      postVM = ''
+        ${pkgs.gzip}/bin/gzip -${toString cfg.compressionLevel} -c -- $diskImage > \
+        $out/nixos-image-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.img.gz
+        rm $diskImage
+      '';
+      format = "raw";
+      partitionTableType = "none";
+      configFile = if cfg.configFile == null then defaultConfigFile else cfg.configFile;
+      inherit (cfg) diskSize;
+      inherit config lib pkgs;
+    };
+  };
+
+  meta.maintainers = with maintainers; [ houstdav000 ];
+}