Updated installation instructions for NixOS

https://www.redhat.com/archives/libvir-list/2020-July/msg00451.html

appvm.go

@@ -163,12 +163,8 @@ func generateVM(path, name string, verbose bool) (realpath, reginfo, qcow2 strin
 	syscall.Unlink("result")
 
 	qcow2 = os.Getenv("HOME") + "/appvm/.fake.qcow2"
-	if _, err = os.Stat(qcow2); os.IsNotExist(err) {
-		system.System("qemu-img", "create", "-f", "qcow2", qcow2, "512M")
-		err = os.Chmod(qcow2, 0400) // qemu run with -snapshot, we only need it for create /dev/vda
-		if err != nil {
-			return
-		}
+	if _, e := os.Stat(qcow2); os.IsNotExist(e) {
+		system.System("qemu-img", "create", "-f", "qcow2", qcow2, "40M")
 	}
 
 	return

default.nix

@@ -1,5 +1,5 @@
+{ pkgs ? import <nixpkgs> {}, ... }:
 let
-  pkgs = import <nixpkgs> {};
   virt-manager-without-menu = pkgs.virt-viewer.overrideAttrs(x: {
     patches = [
       ./patches/0001-Remove-menu-bar.patch
@@ -31,7 +31,7 @@ buildGoModule rec {
   meta = {
     description = "Nix-based app VMs";
     homepage = "https://code.dumpstack.io/tools/${pname}";
-    maintainers = [ lib.maintainers.dump_stack ];
+    maintainers = [ lib.maintainers.dump_stack lib.maintainers.cab404 ];
     license = lib.licenses.gpl3;
   };
 }

docs/installation.rst

@@ -4,22 +4,20 @@ Installation
 NixOS
 -----
 
+First, clone this repo. Then do this:
+
 /etc/nixos/configuration.nix::
 
-  virtualisation.libvirtd = {
+  imports = [
+    /path/to/repo/nixos
+  ];
+
+  virtualizatiom.appvm = {
     enable = true;
-    qemuVerbatimConfig = ''
-      namespaces = []
-      user = "${username}"
-      group = "users"
-    '';
+    user = "${username}";
   };
 
-  users.users."${username}".extraGroups = [ ... "libvirtd" ];
-
-shell::
-
-  nix run -f https://code.dumpstack.io/tools/appvm/archive/master.tar.gz -c appvm
+This is a temporary solution until appvm is upstreamed to nixpkgs or Nix flakes are released.
 
 Ubuntu 20.04
 ------

nixos/default.nix

@@ -0,0 +1,44 @@
+params@{ config, lib, pkgs, ... }:
+let
+  cfg = config.virtualisation.appvm;
+  appvm = import ../. params;
+in with lib; {
+
+  options = {
+    virtualisation.appvm = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          This enables AppVMs and related virtualisation settings.
+        '';
+      };
+      user = mkOption {
+        type = types.str;
+        description = ''
+          AppVM user login. Currenly only AppVMs are supported for a single user only.
+        '';
+      };
+    };
+
+  };
+
+  config = mkIf cfg.enable {
+    virtualisation.libvirtd = {
+      enable = true;
+      qemuVerbatimConfig = ''
+        namespaces = []
+        user = "${cfg.user}"
+        group = "users"
+        remember_owner = 0
+      '';
+    };
+
+    users.users."${cfg.user}" = {
+      packages = [ appvm ];
+      extraGroups = [ "libvirtd" ];
+    };
+
+  };
+
+}