nicolargo / glances

glances/exports/glances_cassandra/__init__.py

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

from glances.exports.export import GlancesExport
from glances.logger import logger


class Export(GlancesExport):
    """This class manages the Cassandra/Scylla export module."""

    def __init__(self, config=None, args=None):
        """Init the Cassandra export IF."""
        super().__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(f"Cannot connect to Cassandra cluster '{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(f"Create keyspace {self.keyspace} on the Cassandra cluster")
            c = (
                f"CREATE KEYSPACE {self.keyspace} WITH "
                f"replication = {{ 'class': 'SimpleStrategy', 'replication_factor': '{self.replication_factor}' }}"
            )
            session.execute(c)
            session.set_keyspace(self.keyspace)

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

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

        return cluster, session

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

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