nicolargo / glances

glances/exports/glances_cassandra.py

# -*- coding: utf-8 -*-
#
# This file is part of Glances.
#
# SPDX-FileCopyrightText: 2022 Nicolas Hennion <nicolas@nicolargo.com>
#
# SPDX-License-Identifier: LGPL-3.0-only
#

"""Cassandra/Scylla interface class."""

import sys
from datetime import datetime
from numbers import Number

from glances.logger import logger
from glances.exports.glances_export import GlancesExport

from cassandra.auth import PlainTextAuthProvider
from cassandra.cluster import Cluster
from cassandra.util import uuid_from_time
from cassandra import InvalidRequest


class Export(GlancesExport):

    """This class manages the Cassandra/Scylla export module."""

    def __init__(self, config=None, args=None):
        """Init the Cassandra export IF."""
        super(Export, self).__init__(config=config, args=args)

        # Mandatory configuration keys (additional to host and port)
        self.keyspace = None

        # Optional configuration keys
        self.protocol_version = 3
        self.replication_factor = 2
        self.table = None
        self.username = None
        self.password = None

        # Load the Cassandra configuration file section
        self.export_enable = self.load_conf(
            'cassandra',
            mandatories=['host', 'port', 'keyspace'],
            options=['protocol_version', 'replication_factor', 'table', 'username', 'password'],
        )
        if not self.export_enable:
            sys.exit(2)

        # Init the Cassandra client
        self.cluster, self.session = self.init()

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

        # if username and/or password are not set the connection will try to connect with no auth
        auth_provider = PlainTextAuthProvider(username=self.username, password=self.password)

        # Cluster
        try:
            cluster = Cluster(
                [self.host],
                port=int(self.port),
                protocol_version=int(self.protocol_version),
                auth_provider=auth_provider,
            )
            session = cluster.connect()
        except Exception as e:
            logger.critical("Cannot connect to Cassandra cluster '%s:%s' (%s)" % (self.host, self.port, e))
            sys.exit(2)

        # Keyspace
        try:
            session.set_keyspace(self.keyspace)

The variable session does not seem to be defined for all execution paths.

        except InvalidRequest:
            logger.info("Create keyspace {} on the Cassandra cluster".format(self.keyspace))
            c = "CREATE KEYSPACE %s WITH replication = { 'class': 'SimpleStrategy', 'replication_factor': '%s' }" % (
                self.keyspace,
                self.replication_factor,
            )
            session.execute(c)
            session.set_keyspace(self.keyspace)

        logger.info(
            "Stats will be exported to Cassandra cluster {} ({}) in keyspace {}".format(
                cluster.metadata.cluster_name, cluster.metadata.all_hosts(), self.keyspace
            )
        )

        # Table
        try:
            session.execute(
                "CREATE TABLE %s (plugin text, time timeuuid, stat map<text,float>, PRIMARY KEY (plugin, time)) \
                    WITH CLUSTERING ORDER BY (time DESC)"
                % self.table
            )
        except Exception:
            logger.debug("Cassandra table %s already exist" % self.table)

        return cluster, session

    def export(self, name, columns, points):
        """Write the points to the Cassandra cluster."""
        logger.debug("Export {} stats to Cassandra".format(name))

        # Remove non number stats and convert all to float (for Boolean)
        data = {k: float(v) for (k, v) in dict(zip(columns, points)).iteritems() if isinstance(v, Number)}

        # Write input to the Cassandra table
        try:
            stmt = "INSERT INTO {} (plugin, time, stat) VALUES (?, ?, ?)".format(self.table)
            query = self.session.prepare(stmt)
            self.session.execute(query, (name, uuid_from_time(datetime.now()), data))
        except Exception as e:
            logger.error("Cannot export {} stats to Cassandra ({})".format(name, e))

    def exit(self):
        """Close the Cassandra export module."""
        # To ensure all connections are properly closed
        self.session.shutdown()
        self.cluster.shutdown()
        # Call the father method
        super(Export, self).exit()