Major config overhaul: use custom modules, setup for multi-host config, and less boilerplate

modules/system/virtualization/docker/default.nix

@@ -0,0 +1,26 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.systemSettings.virtualization.docker;
+  adminUsers = config.systemSettings.adminUsers;
+in {
+  options = {
+    systemSettings.virtualization.docker = {
+      enable = lib.mkEnableOption "Enable docker";
+    };
+  };
+
+  config = {
+    virtualisation.docker = {
+      enable = true;
+      enableOnBoot = true;
+      autoPrune.enable = true;
+    };
+    users.users = builtins.listToAttrs (map (user: { name = user; value = { extraGroups = [ "docker" ];};}) adminUsers);
+    environment.systemPackages = with pkgs; [
+      docker
+      docker-compose
+      lazydocker
+    ];
+  };
+}