event_writer.py

# Copyright 2016 Splunk, Inc.
#
# Licensed under the Apache License, Version 2.0 (the 'License'): you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an 'AS IS' BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

'''
This module provides two kinds of event writers (ClassicEventWriter,
HECEventWriter) to write Splunk modular input events.
'''

import sys
import time
import threading
import logging
import traceback
from abc import ABCMeta, abstractmethod

from splunklib import binding
import solnlib.splunk_rest_client as rest_client
from solnlib.splunkenv import get_splunkd_access_info

import solnlib.utils as utils
from solnlib.hec_config import HECConfig
from solnlib.utils import retry
from solnlib.modular_input.event import XMLEvent, HECEvent

__all__ = ['ClassicEventWriter',
           'HECEventWriter']


class EventWriter(object):
    '''Base class of event writer.
    '''

    __metaclass__ = ABCMeta

    description = 'EventWriter'

    @abstractmethod
    def create_event(self, data, time=None,
                     index=None, host=None, source=None, sourcetype=None,
                     stanza=None, unbroken=False, done=False):
        '''Create a new event.

        :param data: Event data.
        :type data: ``json object``
        :param time: (optional) Event timestamp, default is None.
        :type time: ``float``
        :param index: (optional) The index event will be written to, default
            is None
        :type index: ``string``
        :param host: (optional) Event host, default is None.
        :type host: ``string``
        :param source: (optional) Event source, default is None.
        :type source: ``string``
        :param sourcetype: (optional) Event sourcetype, default is None.
        :type sourcetype: ``string``
        :param stanza: (optional) Event stanza name, default is None.
        :type stanza: ``string``
        :param unbroken: (optional) Event unbroken flag, default is False.
            It is only meaningful when for XMLEvent when using ClassicEventWriter.
        :type unbroken: ``bool``
        :param done: (optional) The last unbroken event, default is False.
            It is only meaningful when for XMLEvent when using ClassicEventWriter.
        :returns: ``bool``
        :returns: A new event object.
        :rtype: ``(XMLEvent, HECEvent)``

        Usage::
           >>> ew = event_writer.HECEventWriter(...)
           >>> event = ew.create_event(
           >>>     data='This is a test data.',
           >>>     time='%.3f' % 1372274622.493,
           >>>     index='main',
           >>>     host='localhost',
           >>>     source='Splunk',
           >>>     sourcetype='misc',
           >>>     stanza='test_scheme://test',
           >>>     unbroken=True,
           >>>     done=True)
        '''

        pass

    @abstractmethod
    def write_events(self, events):
        '''Write events.

        :param events: List of events to write.
        :type events: ``list``

        Usage::
           >>> from solnlib.modular_input import event_writer
           >>> ew = event_writer.EventWriter(...)
           >>> ew.write_events([event1, event2])
        '''

        pass


class ClassicEventWriter(EventWriter):
    '''Classic event writer.

    Use sys.stdout as the output.

    :param lock: (optional) lock to exclusively access stdout.
        by default, it is None and it will use threading safe lock.
        if user would like to make the lock multiple-process safe, user should
        pass in multiprocessing.Lock() instead
    :type lock: ``theading.Lock or multiprocessing.Lock``

    Usage::
        >>> from solnlib.modular_input import event_writer
        >>> ew = event_writer.ClassicEventWriter()
        >>> ew.write_events([event1, event2])
    '''

    description = 'ClassicEventWriter'

    def __init__(self, lock=None):
        if lock is None:
            self._lock = threading.Lock()
        else:
            self._lock = lock

    def create_event(self, data, time=None,
                     index=None, host=None, source=None, sourcetype=None,
                     stanza=None, unbroken=False, done=False):
        '''Create a new XMLEvent object.
        '''

        return XMLEvent(
            data, time=time,
            index=index, host=host, source=source, sourcetype=sourcetype,
            stanza=stanza, unbroken=unbroken, done=done)

    def write_events(self, events):
        if not events:
            return

        stdout = sys.stdout

        with self._lock:
            for event in XMLEvent.format_events(events):
                stdout.write(event)
            stdout.flush()


class HECEventWriter(EventWriter):
    '''Classic event writer.

    Use Splunk HEC as the output.

    :param hec_input_name: Splunk HEC input name.
    :type hec_input_name: ``string``
    :param session_key: Splunk access token.
    :type session_key: ``string``
    :param scheme: (optional) The access scheme, default is None.
    :type scheme: ``string``
    :param host: (optional) The host name, default is None.
    :type host: ``string``
    :param port: (optional) The port number, default is None.
    :type port: ``integer``
    :param hec_uri: (optional) If hec_uri and hec_token are provided, they will
       higher precedence than hec_input_name
    :type hec_token: ``integer``
    :param context: Other configurations for Splunk rest client.
    :type context: ``dict``

    Usage::
        >>> from solnlib.modular_input import event_writer
        >>> ew = event_writer.HECEventWriter(hec_input_name, session_key)
        >>> ew.write_events([event1, event2])
    '''

    WRITE_EVENT_RETRIES = 3
    HTTP_INPUT_CONFIG_ENDPOINT = \
        '/servicesNS/nobody/splunk_httpinput/data/inputs/http'
    HTTP_EVENT_COLLECTOR_ENDPOINT = '/services/collector'

    description = 'HECEventWriter'

    def __init__(self, hec_input_name, session_key,
                 scheme=None, host=None, port=None, hec_uri=None,
                 hec_token=None, **context):
        super(HECEventWriter, self).__init__()
        self._session_key = session_key

        if not all([scheme, host, port]):
            scheme, host, port = get_splunkd_access_info()

        if hec_uri and hec_token:
            scheme, host, hec_port = utils.extract_http_scheme_host_port(
                hec_uri)
        else:
            hec_port, hec_token = self._get_hec_config(
                hec_input_name, session_key, scheme, host, port, **context)

        if not context.get('pool_connections'):
            context['pool_connections'] = 10

        if not context.get('pool_maxsize'):
            context['pool_maxsize'] = 10

        self._rest_client = rest_client.SplunkRestClient(hec_token,
                                                         app='-',
                                                         scheme=scheme,
                                                         host=host,
                                                         port=hec_port,
                                                         **context)

    @retry(exceptions=[binding.HTTPError])
    def _get_hec_config(self, hec_input_name, session_key,
                        scheme, host, port, **context):
        hc = HECConfig(
            session_key, scheme=scheme, host=host, port=port, **context)
        settings = hc.get_settings()
        if utils.is_true(settings.get('disabled')):
            # Enable HEC input
            logging.info('Enabling HEC')
            settings['disabled'] = '0'
            settings['enableSSL'] = context.get('hec_enablessl', '1')
            settings['port'] = context.get('hec_port', '8088')
            hc.update_settings(settings)

        hec_input = hc.get_input(hec_input_name)
        if not hec_input:
            # Create HEC input
            logging.info('Create HEC datainput, name=%s', hec_input_name)
            hinput = {
                'index': context.get('index', 'main'),
            }

            if context.get('sourcetype'):
                hinput['sourcetype'] = context['sourcetype']

            if context.get('token'):
                hinput['token'] = context['token']

            hec_input = hc.create_input(hec_input_name, hinput)

        limits = hc.get_limits()
        HECEvent.max_hec_event_length = int(
            limits.get('max_content_length', 1000000))

        return settings['port'], hec_input['token']

    def create_event(self, data, time=None,
                     index=None, host=None, source=None, sourcetype=None,
                     stanza=None, unbroken=False, done=False):
        '''Create a new HECEvent object.
        '''

        return HECEvent(
            data, time=time,
            index=index, host=host, source=source, sourcetype=sourcetype)

    def write_events(self, events):
        if not events:
            return

        for event in HECEvent.format_events(events):
            for i in xrange(self.WRITE_EVENT_RETRIES):
                try:
                    self._rest_client.post(
                        self.HTTP_EVENT_COLLECTOR_ENDPOINT, body=event,
                        headers=[('Content-Type', 'application/json')])
                    break
                except binding.HTTPError as e:
                    logging.error('Write events through HEC failed: %s.',
                                  traceback.format_exc(e))
                    time.sleep(2 ** (i + 1))