anchor.diff:  
     config = mkIf cfg.enableSingleNode {
   
  -    environment.systemPackages = [ nova ];
  +    environment.systemPackages = [ nova pkgs.euca2ools ];
   
       environment.etc =
         [ # The Paste configuration file for nova-api.
  
positive.code: 
          startOn = "ip-up";
  
          exec = "${nova}/bin/nova-api";
        };
  
  
negative.code: 
      # `qemu-nbd' required the `nbd' kernel module.
      boot.kernelModules = [ "nbd" ];
  
      system.activationScripts.nova =
        ''
          mkdir -m 700 -p /var/lib/nova
  
          # Allow the CA certificate generation script (called by
          # nova-api) to work.
          mkdir -m 700 -p /var/lib/nova/CA /var/lib/nova/CA/private
          cp -p ${nova}/libexec/nova/openssl.cnf.tmpl /var/lib/nova/CA/
  
          # Initialise the SQLite database.        
          ${nova}/bin/nova-manage db sync
        '';
        
      # `nova-api' receives and executes external client requests from
      # tools such as euca2ools.  It listens on port 8773 (XML) and 8774
  