Authenticate to the database.

        Available mechanisms:
        * Username & password
        * X.509

        More information:
        https://api.mongodb.com/python/current/examples/authentication.html

def _authenticate(self, database, username, password, use_x509, server_name, service_check_tags):
        """
        Authenticate to the database.

        Available mechanisms:
        * Username & password
        * X.509

        More information:
        https://api.mongodb.com/python/current/examples/authentication.html
        """
        authenticated = False
        try:
            # X.509
            if use_x509:
                self.log.debug(u"Authenticate `%s`  to `%s` using `MONGODB-X509` mechanism", username, database)
                authenticated = database.authenticate(username, mechanism='MONGODB-X509')

            # Username & password
            else:
                authenticated = database.authenticate(username, password)

        except pymongo.errors.PyMongoError as e:
            self.log.error(u"Authentication failed due to invalid credentials or configuration issues. %s", e)

        if not authenticated:
            message = "Mongo: cannot connect with config %s" % server_name
            self.service_check(self.SERVICE_CHECK_NAME, AgentCheck.CRITICAL, tags=service_check_tags, message=message)
            raise Exception(message)

        return authenticated