anchor.diff:          description = "Nova simple object store service";
   
           startOn = "ip-up";
  +
  +        preStart =
  +          ''
  +            mkdir -m 700 -p /var/lib/nova/images
  +          '';
   
           exec = "${nova}/bin/nova-objectstore --nodaemon";
         };
  
positive.code: 
          startOn = "ip-up";
  
          path = [ pkgs.openssl ];
            
          exec = "${nova}/bin/nova-api";
        };
  
negative.code: 
      system.activationScripts.nova =
        ''
          mkdir -m 755 -p /var/lib/nova
          mkdir -m 755 -p /var/lib/nova/networks
          mkdir -m 700 -p /var/lib/nova/instances
          mkdir -m 700 -p /var/lib/nova/keys
  
          # Allow the CA certificate generation script (called by
          # nova-api) to work.
  