anchor.diff:  
         task = true;
   
  +      path = [ pkgs.curl ];
  +
         script =
           ''
  +          curl="curl --retry 3 --retry-delay 0 --fail"
  +        
             echo "setting host name..."
             ${optionalString (config.networking.hostName == "") ''
  -            ${pkgs.nettools}/bin/hostname $(${pkgs.curl}/bin/curl http://169.254.169.254/1.0/meta-data/hostname)
  +            ${pkgs.nettools}/bin/hostname $($curl http://169.254.169.254/1.0/meta-data/hostname)
             ''}
   
             # Don't download the SSH key if it has already been injected
  
positive.code:         '';
      };
  
  }
  
negative.code:                   chmod 600 /root/.ssh/authorized_keys
                    rm -f /root/key.pub
                fi
            fi
  
            # Extract the intended SSH host key for this machine from
            # the supplied user data, if available.  Otherwise sshd will
            # generate one normally.
            $curl http://169.254.169.254/2011-01-01/user-data > /root/user-data || true
            key="$(sed 's/|/\n/g; s/SSH_HOST_DSA_KEY://; t; d' /root/user-data)"
            key_pub="$(sed 's/SSH_HOST_DSA_KEY_PUB://; t; d' /root/user-data)"
            if [ -n "$key" -a -n "$key_pub" -a ! -e /etc/ssh/ssh_host_dsa_key ]; then
                mkdir -m 0755 -p /etc/ssh
                (umask 077; echo "$key" > /etc/ssh/ssh_host_dsa_key)
                echo "$key_pub" > /etc/ssh/ssh_host_dsa_key.pub
            fi
          '';
      };
  