[microvm] fix comparision

this reduces build times drastically

doc/src/SUMMARY.md

@@ -14,3 +14,4 @@
     - [How-to]()
         - [Updates](./anleitung/updates.md)
         - [Rollbacks](./anleitung/rollback.md)
+        - [MicroVM](./anleitung/microvm.md)

doc/src/anleitung/microvm.md

@@ -0,0 +1,39 @@
+### Declaring a MicroVM
+
+The hosts nixosSystems modules should be declared using the ```makeMicroVM``` helper function.
+Use durruti as orientation:
+``` nix
+    modules = makeMicroVM "durruti" "10.0.0.5" [
+      ./durruti/configuration.nix
+    ];
+```
+
+"durruti" is the hostname.  
+"10.0.0.5" is the IP assigned to its tap interface.  
+
+### Testing MicroVMs locally
+MicroVMs can be built and run easily on your local host.
+For durruti this is done by:
+``` bash
+sudo nix run .\#nixosConfigurations.durruti.config.microvm.declaredRunner
+```
+
+It seems to be necessary to run this as root so that the according tap interface can be created.
+To be able to ping the VM or give Internet Access to the VM your host needs to be setup as described below.
+
+### Host Setup
+To provide network access to the VMs a bridge interface needs to be created on your host.
+For that:
+- Add the infrastructure flake as input to your hosts flake  
+- Add ```inputs.malobeo.nixosModules.malobeo``` to your hosts imports
+- enable the host bridge: ```services.malobeo.microvm.enableHostBridge = true;```
+
+If you want to provide Internet access to the VM it is necessary to create a nat.
+This could be done like this:
+``` nix
+networking.nat = {
+  enable = true;
+  internalInterfaces = [ "microvm" ];
+  externalInterface = "eth0"; #change to your interface name
+};
+```

machines/configuration.nix

@@ -46,6 +46,11 @@ let
     {
       microvm = {
         hypervisor = "qemu";
+        shares = [ {
+          tag = "ro-store";
+          source = "/nix/store";
+          mountPoint = "/nix/.ro-store";
+        } ];
         interfaces = [
           {
             type = "tap";

machines/modules/malobeo/microvm_host.nix

@@ -13,6 +13,14 @@ in
         type = types.bool;
         description = lib.mdDoc "Setup bridge device for microvms.";
       };
+
+      deployHosts = mkOption {
+        default = [];
+        type = types.listOf string;
+        description = ''
+          List hostnames of MicroVMs that should be automatically initializes and autostart
+        '';
+      };
     };
   };
 
@@ -48,5 +56,24 @@ in
         networkConfig.Bridge = "microvm";
       };
     };
+
+    imports = mkIf (lib.length cfg.deployHosts != 0) [
+      inputs.microvm.nixosModules.host
+    ];
+
+    microvm.autostart = cfg.deployHosts;
+    microvm.vms = 
+    let
+      # Map the values to each hostname to then generate a Attrs using listToAttrs
+      mapperFunc = name: { inherit name; value = {
+          # Host build-time reference to where the MicroVM NixOS is defined
+          # under nixosConfigurations
+          flake = self;
+          # Specify from where to let `microvm -u` update later on
+          updateFlake = "git+https://git.dynamicdiscord.de/kalipso/infrastructure?ref=microvm";
+        }; };
+    in
+    mkIf (lib.length cfg.deployHosts != 0)
+    builtins.listToAttrs (map mapperFunc cfg.deployHosts);
   };
 }

outputs.nix

@@ -41,7 +41,7 @@ in (utils.lib.eachSystem (builtins.filter filter_system utils.lib.defaultSystems
     apps = {
       docs = {
         type = "app";
-        program = builtins.toString (pkgs.writeScript "docs" ''
+        program = builtins.toString (pkgs.writeShellScript "docs" ''
           ${pkgs.mdbook}/bin/mdbook serve --open ./doc
         '');
       };