main.py

"""
This script queries Inventory Provider for changes
and configures Sensu with the snmp polling checks
required by BRIAN.

.. code-block:: console

    % brian-polling-manager --help
    Usage: brian-polling-manager [OPTIONS]

      Update BRIAN snmp checks based on Inventory Provider data.

    Options:
      --config TEXT         configuration filename
      --force / --no-force  update even if inventory hasn't been updated
      --help                Show this message and exit.

The required configuration file must be
formatted according to the following schema:

.. asjson::
    brian_polling_manager.configuration.CONFIG_SCHEMA

"""
import json
import logging

import click
import jsonschema
from statsd import StatsClient

from brian_polling_manager import inventory, interfaces, configuration

logger = logging.getLogger(__name__)

REFRESH_RESULT_SCHEMA = {
    '$schema': 'http://json-schema.org/draft-07/schema#',
    'definitions': {
        'refresh-result': {
            'type': 'object',
            'properties': {
                'checks': {'type': 'integer'},
                'input': {'type': 'integer'},
                'created': {'type': 'integer'},
                'updated': {'type': 'integer'},
                'deleted': {'type': 'integer'}
            },
            'required': ['checks', 'input', 'created', 'updated', 'deleted'],
            'additionalProperties': False
        }
    },
    'type': 'object',
    'properties': {
        'interfaces': {'$ref': '#/definitions/refresh-result'}
    },
    'required': ['interfaces'],
    'additionalProperties': False
}


def refresh(config, force=False):
    """
    reload inventory data & update sensu checks

    The output will be a dict formatted according to the following schema:

    .. asjson::
        brian_polling_manager.main.REFRESH_RESULT_SCHEMA

    :param config: a dict returned by configuration.load_config
    :param force: if True, reload inventory data even if timestamp is same
    :return: a dict, formatted as above
    """
    state = configuration.State(config['statedir'])
    last = inventory.last_update_timestamp(config['inventory'])
    if force or not last or last != state.last:
        state.last = last
        state.interfaces = inventory.load_interfaces(config['inventory'])

    result = {
        'interfaces': interfaces.refresh(config['sensu'], state)
    }

    statsd_config = config.get('statsd', None)
    if statsd_config:
        statsd = StatsClient(
            host=statsd_config['hostname'],
            port=statsd_config['port'],
            prefix=f'{statsd_config["prefix"]}_interfaces')
        statsd.gauge('checks', result['interfaces']['checks'])
        statsd.gauge('input', result['interfaces']['input'])
        statsd.gauge('created', result['interfaces']['created'])
        statsd.gauge('updated', result['interfaces']['updated'])
        statsd.gauge('deleted', result['interfaces']['deleted'])

    jsonschema.validate(result, REFRESH_RESULT_SCHEMA)  # sanity
    return result

def _validate_config(_ctx, _param, file):
    """
    loads, validates and returns configuration parameters

    :param _ctx: unused
    :param _param: unused
    :param value: file (file-like object open for reading)
    :return: a dict containing configuration parameters
    """
    try:
        return configuration.load_config(file)
    except (json.JSONDecodeError, jsonschema.ValidationError, OSError,
            AttributeError, ValueError, TypeError, ImportError) as e:
        raise click.BadParameter(str(e))


@click.command()
@click.option(
    '--config',
    default=None,
    type=click.File('r'),
    callback=_validate_config,
    help='configuration filename')
@click.option(
    '--force/--no-force',
    default=False,
    help="refresh inventory data even if it hasn't been updated")
def cli(config, force):
    """
    Update BRIAN snmp checks based on Inventory Provider data.
    """
    logger.info(json.dumps(refresh(config, force)))


if __name__ == '__main__':
    cli()