From c20a589de267dded1c096e1c1339b5efe5156f1f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Isma=C3=ABl=20Bouya?= <ismael.bouya@normalesup.org>
Date: Fri, 25 Jun 2021 10:31:40 +0200
Subject: Make libvirt pools declarative.

---
 modules/private/system/dilion/vms.nix | 63 ++++++++++++++++++++++++++++-------
 1 file changed, 51 insertions(+), 12 deletions(-)

diff --git a/modules/private/system/dilion/vms.nix b/modules/private/system/dilion/vms.nix
index 8d5a57b..af96622 100644
--- a/modules/private/system/dilion/vms.nix
+++ b/modules/private/system/dilion/vms.nix
@@ -1,6 +1,28 @@
 # inspired from https://nixos.wiki/wiki/Virtualization_in_NixOS
 { config, pkgs, lib, ... }@args:
 let
+  pools = {
+    niximages = {
+      type = "dir";
+      target = "/etc/libvirtd/base-images";
+    };
+    buildbot-disks = rec {
+      preStart = ''
+        mkdir -p ${target}
+      '';
+      type = "dir";
+      target = "/var/lib/libvirt/images/buildbot-disks";
+    };
+    zfspool = {
+      # pool-define-as --name zfspool --source-name zpool/libvirt --type zfs
+      type = "zfs";
+      xml = ''
+        <source>
+          <name>zpool/libvirt</name>
+        </source>
+      '';
+    };
+  };
   networks = {
     immae = {
       bridgeNumber = "1";
@@ -28,15 +50,6 @@ let
       network = "immae";
       diskSize = "10GiB";
       destroyVolumeOnExit = true;
-      preStart = ''
-        if ! ${pkgs.libvirt}/bin/virsh pool-info --pool niximages &> /dev/null; then
-          pool-create-as --name niximages --type dir --target /etc/libvirtd/base-images/
-        fi
-        if ! ${pkgs.libvirt}/bin/virsh pool-info --pool buildbot-disks &> /dev/null; then
-          mkdir -p /var/lib/libvirt/images/buildbot-disks
-          pool-create-as --name buildbot-disks --type dir --target /var/lib/libvirt/images/buildbot-disks
-        fi
-      '';
     };
   };
   toImage = f: "${import ./vms/base_image.nix f (args // { myEnv = config.myEnv; })}/nixos.qcow2";
@@ -45,8 +58,8 @@ in
   environment.etc."libvirtd/base-images/nixos.qcow2".source = toImage ./vms/base_configuration.nix;
   environment.etc."libvirtd/base-images/buildbot.qcow2".source = toImage ./vms/buildbot_configuration.nix;
   systemd.services = lib.mapAttrs' (name: guest: lib.nameValuePair "libvirtd-guest-${name}" {
-    after = [ "libvirtd.service" "libvirtd-network-${guest.network}.service" ];
-    requires = [ "libvirtd.service" "libvirtd-network-${guest.network}.service" ];
+    after = [ "libvirtd.service" "libvirtd-pool-${guest.pool}.service" "libvirtd-network-${guest.network}.service" ];
+    requires = [ "libvirtd.service" "libvirtd-pool-${guest.pool}.service" "libvirtd-network-${guest.network}.service" ];
     wantedBy = [ "multi-user.target" ];
     serviceConfig = {
       Type = "oneshot";
@@ -142,5 +155,31 @@ in
     preStop = ''
       ${pkgs.libvirt}/bin/virsh net-destroy '${name}'
     '';
-  }) networks);
+  }) networks) // (lib.mapAttrs' (name: pool: lib.nameValuePair "libvirtd-pool-${name}" {
+    after = [ "libvirtd.service" ];
+    requires = [ "libvirtd.service" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = "yes";
+    };
+    script = let
+      xml = pkgs.writeText "libvirt-pool-${name}.xml" ''
+        <pool type="${pool.type}">
+          <name>${name}</name>
+          <uuid>UUID</uuid>
+          ${pool.xml or ""}
+          ${if pool ? target then ''
+            <target>
+              <path>${pool.target}</path>
+            </target>
+          '' else ""}
+        </pool>
+      '';
+    in pool.preStart or "" + ''
+      uuid="$(${pkgs.libvirt}/bin/virsh pool-uuid '${name}' || true)"
+      ${pkgs.libvirt}/bin/virsh pool-define <(sed "s/UUID/$uuid/" '${xml}')
+      ${pkgs.libvirt}/bin/virsh pool-start '${name}' || true
+    '';
+  }) pools);
 }
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