Init the connection to the OpenTSDB server.

def init(self):
        """Init the connection to the OpenTSDB server."""
        if not self.export_enable:
            return None

        try:
            db = potsdb.Client(self.host,
                               port=int(self.port),
                               check_host=True)
        except Exception as e:
            logger.critical("Cannot connect to OpenTSDB server %s:%s (%s)" % (self.host, self.port, e))
            sys.exit(2)

        return db