nix: add development vm

This commit adds back the ability to run a development VM with docspell.
See updated documentation for examples.

nix/checks/configuration-test.nix

@@ -15,7 +15,7 @@ in
   i18n = {
     defaultLocale = "en_US.UTF-8";
   };
-  console.keyMap = "de";
+  console.keyMap = "us";
 
   users.users.root = {
     password = "root";
@@ -88,6 +88,9 @@ in
     firewall.allowedTCPPorts = [ 7880 ];
   };
 
-  system.stateVersion = "22.05";
+  system.stateVersion = "22.11";
+
+  # This slows down the build of a vm
+  documentation.enable = false;
 
 }

nix/dev-vm/default.nix

@@ -0,0 +1,28 @@
+# NOTE: modulesPath and imports are taken from nixpkgs#59219
+{ modulesPath, pkgs, lib, ... }: {
+  imports = [ (modulesPath + "/virtualisation/qemu-vm.nix") ];
+  services.openssh = {
+    enable = true;
+    permitRootLogin = "yes";
+  };
+
+  services.docspell-restserver = {
+    openid = lib.mkForce [ ];
+    backend = lib.mkForce {
+      signup = {
+        mode = "open";
+      };
+    };
+  };
+
+  # Otherwise oomkiller kills docspell
+  virtualisation.memorySize = 2048;
+
+  virtualisation.forwardPorts = [
+    # SSH
+    { from = "host"; host.port = 64022; guest.port = 22; }
+    # Docspell
+    { from = "host"; host.port = 64080; guest.port = 7880; }
+  ];
+
+}

nix/flake.nix

@@ -115,5 +115,20 @@
         joex = ((import ./modules/joex.nix) self.overlays.default);
       };
 
+      nixosConfigurations =
+        let
+          lib = nixpkgs.lib;
+        in
+        {
+          dev-vm = lib.makeOverridable nixpkgs.lib.nixosSystem {
+            system = "x86_64-linux";
+            modules = [
+              self.nixosModules.default
+              ./checks
+              # nixos-shell specific module. Should be kept outside nix flake checks
+              ./dev-vm
+            ];
+          };
+        };
     };
 }