Combine OVA generation steps

Previously this was done in three derivations (one to build the raw
disk image, one to convert to OVA, one to add a hydra-build-products
file). Now it's done in one step to reduce the amount of copying
to/from S3. In particular, not uploading the raw disk image prevents
us from hitting hydra-queue-runner's size limit of 2 GiB.

nixos/lib/make-disk-image.nix

···
 , # Shell code executed after the VM has finished.
   postVM ? ""
 
+, name ? "nixos-disk-image"
 }:
 
 with lib;
 
 pkgs.vmTools.runInLinuxVM (
-  pkgs.runCommand "nixos-disk-image"
+  pkgs.runCommand name
     { preVM =
         ''
           mkdir $out

nixos/modules/virtualisation/virtualbox-image.nix

···
 
   config = {
 
-    system.build.virtualBoxImage = import ../../lib/make-disk-image.nix {
+    system.build.virtualBoxOVA = import ../../lib/make-disk-image.nix {
+      name = "nixos-ova-${config.system.nixosLabel}-${pkgs.stdenv.system}";
+
       inherit pkgs lib config;
       partitioned = true;
       diskSize = cfg.baseImageSize;
···
       postVM =
         ''
           echo "creating VirtualBox disk image..."
-          ${pkgs.vmTools.qemu}/bin/qemu-img convert -f raw -O vdi $diskImage $out/disk.vdi
+          ${pkgs.vmTools.qemu}/bin/qemu-img convert -f raw -O vdi $diskImage disk.vdi
           rm $diskImage
+
+          echo "creating VirtualBox VM..."
+          export HOME=$PWD
+          export PATH=${pkgs.linuxPackages.virtualbox}/bin:$PATH
+          vmName="NixOS ${config.system.nixosLabel} (${pkgs.stdenv.system})"
+          VBoxManage createvm --name "$vmName" --register \
+            --ostype ${if pkgs.stdenv.system == "x86_64-linux" then "Linux26_64" else "Linux26"}
+          VBoxManage modifyvm "$vmName" \
+            --memory 1536 --acpi on --vram 32 \
+            ${optionalString (pkgs.stdenv.system == "i686-linux") "--pae on"} \
+            --nictype1 virtio --nic1 nat \
+            --audiocontroller ac97 --audio alsa \
+            --rtcuseutc on \
+            --usb on --mouse usbtablet
+          VBoxManage storagectl "$vmName" --name SATA --add sata --portcount 4 --bootable on --hostiocache on
+          VBoxManage storageattach "$vmName" --storagectl SATA --port 0 --device 0 --type hdd \
+            --medium disk.vdi
+
+          echo "exporting VirtualBox VM..."
+          mkdir -p $out
+          fn="$out/nixos-${config.system.nixosLabel}-${pkgs.stdenv.system}.ova"
+          VBoxManage export "$vmName" --output "$fn"
+
+          mkdir -p $out/nix-support
+          echo "file ova $fn" >> $out/nix-support/hydra-build-products
         '';
     };
-
-    system.build.virtualBoxOVA = pkgs.runCommand "virtualbox-ova"
-      { buildInputs = [ pkgs.linuxPackages.virtualbox ];
-        vmName = "NixOS ${config.system.nixosLabel} (${pkgs.stdenv.system})";
-        fileName = "nixos-image-${config.system.nixosLabel}-${pkgs.stdenv.system}.ova";
-      }
-      ''
-        echo "creating VirtualBox VM..."
-        export HOME=$PWD
-        VBoxManage createvm --name "$vmName" --register \
-          --ostype ${if pkgs.stdenv.system == "x86_64-linux" then "Linux26_64" else "Linux26"}
-        VBoxManage modifyvm "$vmName" \
-          --memory 1536 --acpi on --vram 32 \
-          ${optionalString (pkgs.stdenv.system == "i686-linux") "--pae on"} \
-          --nictype1 virtio --nic1 nat \
-          --audiocontroller ac97 --audio alsa \
-          --rtcuseutc on \
-          --usb on --mouse usbtablet
-        VBoxManage storagectl "$vmName" --name SATA --add sata --portcount 4 --bootable on --hostiocache on
-        VBoxManage storageattach "$vmName" --storagectl SATA --port 0 --device 0 --type hdd \
-          --medium ${config.system.build.virtualBoxImage}/disk.vdi
-
-        echo "exporting VirtualBox VM..."
-        mkdir -p $out
-        VBoxManage export "$vmName" --output "$out/$fileName"
-      '';
 
     fileSystems."/".device = "/dev/disk/by-label/nixos";
 

nixos/release.nix

···
 
     with import nixpkgs { inherit system; };
 
-    let
-
-      config = (import lib/eval-config.nix {
-        inherit system;
-        modules =
-          [ versionModule
-            ./modules/installer/virtualbox-demo.nix
-          ];
-      }).config;
-
-    in
-      # Declare the OVA as a build product so that it shows up in Hydra.
-      hydraJob (runCommand "nixos-ova-${config.system.nixosVersion}-${system}"
-        { meta = {
-            description = "NixOS VirtualBox appliance (${system})";
-            maintainers = maintainers.eelco;
-          };
-          ova = config.system.build.virtualBoxOVA;
-          preferLocalBuild = true;
-        }
-        ''
-          mkdir -p $out/nix-support
-          fn=$(echo $ova/*.ova)
-          echo "file ova $fn" >> $out/nix-support/hydra-build-products
-        '') # */
+    hydraJob ((import lib/eval-config.nix {
+      inherit system;
+      modules =
+        [ versionModule
+          ./modules/installer/virtualbox-demo.nix
+        ];
+    }).config.system.build.virtualBoxOVA)
 
   );