From bdfa5122ea1b56e41768853b859ff16758287919 Mon Sep 17 00:00:00 2001
From: Matthieu Coudron <mattator@gmail.com>
Date: Thu, 19 Sep 2019 01:27:42 +0900
Subject: [PATCH]  Convert libvirtd to use make-disk-image

This fixes #931 by reusing the
image builder of <nixpkgs/nixos/lib/make-disk-image.nix>. This image
builder produces nixos.qcow2 instead of disk.qcow2. This image is now
"baseless", so it obsoletes "qemu-img rebase". We can also remove our
special-case image builder libvirtd-image.nix as a whole.
---
 nix/libvirtd-image.nix           | 89 --------------------------------
 nix/libvirtd.nix                 | 38 +++++---------
 nixopsvirtd/backends/libvirtd.py |  6 +--
 3 files changed, 13 insertions(+), 120 deletions(-)
 delete mode 100644 nix/libvirtd-image.nix

diff --git a/nix/libvirtd-image.nix b/nix/libvirtd-image.nix
deleted file mode 100644
index 1325f1a..0000000
--- a/nix/libvirtd-image.nix
+++ /dev/null
@@ -1,89 +0,0 @@
-{ system ? builtins.currentSystem, size ? "10" }:
-let
-  pkgs = import <nixpkgs> {};
-  config = (import <nixpkgs/nixos/lib/eval-config.nix> {
-    inherit system;
-    modules = [ {
-      fileSystems."/".device = "/dev/disk/by-label/nixos";
-
-      boot.loader.grub.version = 2;
-      boot.loader.grub.device = "/dev/sda";
-      boot.loader.timeout = 0;
-
-      services.openssh.enable = true;
-      services.openssh.startWhenNeeded = false;
-      services.openssh.extraConfig = "UseDNS no";
-    } ];
-  }).config;
-
-in pkgs.vmTools.runInLinuxVM (
-  pkgs.runCommand "libvirtd-image"
-    { memSize = 768;
-      preVM =
-        ''
-          mkdir $out
-          diskImage=$out/image
-          ${pkgs.vmTools.qemu}/bin/qemu-img create -f qcow2 $diskImage "${size}G"
-          mv closure xchg/
-        '';
-      postVM =
-        ''
-          mv $diskImage $out/disk.qcow2
-        '';
-      buildInputs = [ pkgs.utillinux pkgs.perl ];
-      exportReferencesGraph =
-        [ "closure" config.system.build.toplevel ];
-    }
-    ''
-      # Create a single / partition.
-      ${pkgs.parted}/sbin/parted /dev/vda mklabel msdos
-      ${pkgs.parted}/sbin/parted /dev/vda -- mkpart primary ext2 1M -1s
-
-      # Create an empty filesystem and mount it.
-      ${pkgs.e2fsprogs}/sbin/mkfs.ext4 -L nixos /dev/vda1
-      ${pkgs.e2fsprogs}/sbin/tune2fs -c 0 -i 0 /dev/vda1
-      mkdir /mnt
-      mount /dev/vda1 /mnt
-
-      # The initrd expects these directories to exist.
-      mkdir /mnt/dev /mnt/proc /mnt/sys
-      mount --bind /proc /mnt/proc
-      mount --bind /dev /mnt/dev
-      mount --bind /sys /mnt/sys
-
-      # Copy all paths in the closure to the filesystem.
-      storePaths=$(perl ${pkgs.pathsFromGraph} /tmp/xchg/closure)
-
-      echo "filling Nix store..."
-      mkdir -p /mnt/nix/store
-      set -f
-      cp -prd $storePaths /mnt/nix/store/
-
-      mkdir -p /mnt/etc/nix
-      echo 'build-users-group = ' > /mnt/etc/nix/nix.conf
-
-      # Register the paths in the Nix database.
-      printRegistration=1 perl ${pkgs.pathsFromGraph} /tmp/xchg/closure | \
-          chroot /mnt ${config.nix.package.out}/bin/nix-store --load-db
-
-      # Create the system profile to allow nixos-rebuild to work.
-      chroot /mnt ${config.nix.package.out}/bin/nix-env \
-          -p /nix/var/nix/profiles/system --set ${config.system.build.toplevel}
-
-      # `nixos-rebuild' requires an /etc/NIXOS.
-      mkdir -p /mnt/etc/nixos
-      touch /mnt/etc/NIXOS
-
-      # `switch-to-configuration' requires a /bin/sh
-      mkdir -p /mnt/bin
-      ln -s ${config.system.build.binsh}/bin/sh /mnt/bin/sh
-
-      # Generate the GRUB menu.
-      ln -s vda /dev/sda
-      chroot /mnt ${config.system.build.toplevel}/bin/switch-to-configuration boot
-
-      umount /mnt/proc /mnt/dev /mnt/sys
-      umount /mnt
-    ''
-)
-
diff --git a/nix/libvirtd.nix b/nix/libvirtd.nix
index 03eb128..e956bd4 100644
--- a/nix/libvirtd.nix
+++ b/nix/libvirtd.nix
@@ -3,33 +3,19 @@
 with lib;
 
 let
-  sz = toString config.deployment.libvirtd.baseImageSize;
-  base_image = import ./libvirtd-image.nix { size = sz; };
   the_key = builtins.getEnv "NIXOPS_LIBVIRTD_PUBKEY";
-  ssh_image = pkgs.vmTools.runInLinuxVM (
-    pkgs.runCommand "libvirtd-ssh-image"
-      { memSize = 768;
-        preVM =
-          ''
-            mkdir $out
-            diskImage=$out/image
-            ${pkgs.vmTools.qemu}/bin/qemu-img create -f qcow2 -b ${base_image}/disk.qcow2 $diskImage
-          '';
-        buildInputs = [ pkgs.utillinux ];
-        postVM =
-          ''
-            mv $diskImage $out/disk.qcow2
-          '';
-      }
-      ''
-        mkdir /mnt
-        mount /dev/vda1 /mnt
-
-        mkdir -p /mnt/etc/ssh/authorized_keys.d
-        echo '${the_key}' > /mnt/etc/ssh/authorized_keys.d/root
-        umount /mnt
-      ''
-  );
+  ssh_image = import <nixpkgs/nixos/lib/make-disk-image.nix> {
+    name = "libvirtd-ssh-image";
+    format = "qcow2";
+    diskSize = config.deployment.libvirtd.baseImageSize * 1024;
+    config = config;
+    contents = [{
+      source = (pkgs.writeText "authorized_keys.d-root" the_key);
+      target = "/etc/ssh/authorized_keys.d/root";
+    }];
+    lib = pkgs.lib;
+    inherit pkgs;
+  };
 in
 
 {
diff --git a/nixopsvirtd/backends/libvirtd.py b/nixopsvirtd/backends/libvirtd.py
index 1e58ffb..e383b40 100644
--- a/nixopsvirtd/backends/libvirtd.py
+++ b/nixopsvirtd/backends/libvirtd.py
@@ -192,11 +192,7 @@ def _prepare_storage_volume(self):
             capture_stdout=True, env=newEnv).rstrip()
 
         temp_disk_path = os.path.join(self.depl.tempdir, 'disk-{}.qcow2'.format(self.name))
-        shutil.copyfile(os.path.join(temp_image_path, 'disk.qcow2'), temp_disk_path)
-        # Rebase onto empty backing file to prevent breaking the disk image
-        # when the backing file gets garbage collected.
-        self._logged_exec(["qemu-img", "rebase", "-f", "qcow2", "-b",
-                           "", temp_disk_path])
+        shutil.copyfile(os.path.join(temp_image_path, 'nixos.qcow2'), temp_disk_path)
 
         self.logger.log("uploading disk image...")
         image_info = self._get_image_info(temp_disk_path)