feat: add unified microvm & container definition; add net, misc, disko lib extension

modules/guests/container.nix

@@ -0,0 +1,64 @@
+guestName: guestCfg: {
+  config,
+  inputs,
+  lib,
+  pkgs,
+  ...
+}: let
+  inherit
+    (lib)
+    flip
+    mapAttrs'
+    nameValuePair
+    ;
+in {
+  ephemeral = true;
+  privateNetwork = true;
+  autoStart = guestCfg.autostart;
+  macvlans = ["${guestCfg.container.macvlan}:${guestCfg.networking.mainLinkName}"];
+  extraFlags = [
+    "--uuid=${builtins.substring 0 32 (builtins.hashString "sha256" guestName)}"
+  ];
+  bindMounts = flip mapAttrs' guestCfg.zfs (
+    _: zfsCfg:
+      nameValuePair zfsCfg.guestMountpoint {
+        hostPath = zfsCfg.hostMountpoint;
+        isReadOnly = false;
+      }
+  );
+  nixosConfiguration = inputs.nixpkgs.lib.nixosSystem {
+    specialArgs = guestCfg.extraSpecialArgs;
+    prefix = ["nodes" "${config.node.name}-${guestName}" "config"];
+    system = null;
+    modules =
+      [
+        {
+          boot.isContainer = true;
+          networking.useHostResolvConf = false;
+
+          # We cannot force the package set via nixpkgs.pkgs and
+          # inputs.nixpkgs.nixosModules.readOnlyPkgs, since some nixosModules
+          # like nixseparatedebuginfod depend on adding packages via nixpkgs.overlays.
+          # So we just mimic the options and overlays defined by the passed pkgs set.
+          nixpkgs.hostPlatform = config.nixpkgs.hostPlatform.system;
+          nixpkgs.overlays = pkgs.overlays;
+          nixpkgs.config = pkgs.config;
+
+          # Bind the /guest/* paths from above so impermancence doesn't complain.
+          # We bind-mount stuff from the host to itself, which is perfectly defined
+          # and not recursive. This allows us to have a fileSystems entry for each
+          # bindMount which other stuff can depend upon (impermanence adds dependencies
+          # to the state fs).
+          fileSystems = flip mapAttrs' guestCfg.zfs (_: zfsCfg:
+            nameValuePair zfsCfg.guestMountpoint {
+              neededForBoot = true;
+              fsType = "none";
+              device = zfsCfg.guestMountpoint;
+              options = ["bind"];
+            });
+        }
+        (import ./common-guest-config.nix guestName guestCfg)
+      ]
+      ++ guestCfg.modules;
+  };
+}