change nixos -> nix

nix/virtual/default.nix

@@ -0,0 +1,94 @@
+{ pkgs, lib, config, hypervisorConfig, ... }: {
+  imports = [ ./docker_swarm.nix ];
+
+  options.lab.vm = {
+    # TODO: make global.
+    baseMACAddress = lib.mkOption {
+      default = "BA:DB:EE:F0:00:00";
+      type = lib.types.str;
+      description = ''
+        Base MAC address for VMs in the DMZ.
+      '';
+    };
+
+    id = lib.mkOption {
+      type = lib.types.int;
+      description = ''
+        Unique identifier of this VM from wich the MAC address is derived.
+      '';
+    };
+
+    shares = lib.mkOption {
+      default = [ ];
+      description = ''
+        Directories mounted on the VM using VirtioFS.
+      '';
+      type = lib.types.listOf (lib.types.submodule ({ config, ... }: {
+        options = {
+          name = lib.mkOption {
+            type = lib.types.str;
+            description = ''
+              The name of the directory share.
+            '';
+          };
+
+          mountPoint = lib.mkOption {
+            type = lib.types.str;
+            description = ''
+              The mount point of the directory share inside the virtual machine.
+            '';
+          };
+        };
+      }));
+    };
+  };
+
+  config = {
+    system.stateVersion = hypervisorConfig.system.stateVersion;
+
+    lab.vm.shares = [{
+      name = "host_keys";
+      mountPoint = "/etc/ssh/host_keys";
+    }];
+
+    services.openssh =
+      let
+        hostKeyPath = "/etc/ssh/host_keys/ssh_host_ed25519_key";
+      in
+      {
+        hostKeys = [{
+          path = hostKeyPath;
+          type = "ed25519";
+        }];
+
+        extraConfig = ''
+          HostKey ${hostKeyPath}
+        '';
+      };
+
+    microvm = {
+      # TODO: make this dependent on the host CPU
+      vcpu = 4;
+
+      shares = [{
+        source = "/nix/store";
+        mountPoint = "/nix/.ro-store";
+        tag = "ro-store";
+        proto = "virtiofs";
+      }] ++ map
+        (share: {
+          source = "/var/lib/microvms/${config.networking.hostName}/shares/${share.name}";
+          mountPoint = share.mountPoint;
+          tag = share.name;
+          proto = "virtiofs";
+        })
+        config.lab.vm.shares;
+
+      interfaces = [{
+        type = "tap";
+        id = "vm-${config.networking.hostName}";
+        mac = pkgs.lib.net.mac.add config.lab.vm.id config.lab.vm.baseMACAddress;
+      }];
+    };
+  };
+}

nix/virtual/docker_swarm.nix

@@ -0,0 +1,39 @@
+{ pkgs, lib, config, machine, ... }:
+let
+  cfg = config.lab.dockerSwarm;
+in
+{
+  options.lab.dockerSwarm.enable = lib.mkOption {
+    default = false;
+    type = lib.types.bool;
+    description = ''
+      Whether to enable Docker Swarm on this host.
+    '';
+  };
+
+  config = lib.mkIf cfg.enable {
+    lab.vm.shares = lib.mkIf machine.isVirtual [{
+      name = "docker";
+      mountPoint = "/var/lib/docker";
+    }];
+
+    networking = {
+      nftables.enable = lib.mkForce false;
+      firewall.enable = lib.mkForce false;
+    };
+
+    virtualisation.docker = {
+      enable = true;
+      liveRestore = false;
+    };
+
+    environment.systemPackages = [
+      (pkgs.python311.withPackages (python-pkgs: with python-pkgs; [
+        docker
+        requests
+        jsondiff
+        pyyaml
+      ]))
+    ];
+  };
+}