[microvm] automatic update from master every 20mins

machines/modules/malobeo/microvm_host.nix

@@ -85,5 +85,36 @@ in
         }; };
     in
     builtins.listToAttrs (map mapperFunc cfg.deployHosts);
+
+    systemd.services = builtins.foldl' (services: name: services // {
+      "microvm-update@${name}" = {
+        description = "Update MicroVMs automatically";
+        after = [ "network-online.target" ];
+        wants = [ "network-online.target" ];
+        unitConfig.ConditionPathExists = "/var/lib/microvms/${name}";
+        serviceConfig = {
+          LimitNOFILE = "1048576";
+          Type = "oneshot";
+        };
+        path = with pkgs; [ nix git ];
+        environment.HOME = config.users.users.root.home;
+        scriptArgs = "%i";
+        script = ''
+          /run/current-system/sw/bin/microvm -Ru ${name}
+        '';
+      };
+    }) {} (cfg.deployHosts);
+
+    systemd.timers = builtins.foldl' (timers: name: timers // {
+    "microvm-update-${name}" = {
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        Unit = "microvm-update@${name}.service";
+        # three times per hour
+        OnCalendar = "*:0,20,40:00";
+        Persistent = true;
+      };
+    };
+  }) {} (cfg.deployHosts);
   };
 }