osm_mon/evaluator/backends/prometheus.py

   1 # -*- coding: utf-8 -*-
   2
   3 # Copyright 2018 Whitestack, LLC
   4 # *************************************************************
   5
   6 # This file is part of OSM Monitoring module
   7 # All Rights Reserved to Whitestack, LLC
   8
   9 # Licensed under the Apache License, Version 2.0 (the "License"); you may
  10 # not use this file except in compliance with the License. You may obtain
  11 # a copy of the License at
  12
  13 #         http://www.apache.org/licenses/LICENSE-2.0
  14
  15 # Unless required by applicable law or agreed to in writing, software
  16 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  17 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  18 # License for the specific language governing permissions and limitations
  19 # under the License.
  20 # For those usages not covered by the Apache License, Version 2.0 please
  21 # contact: bdiaz@whitestack.com or glavado@whitestack.com
  22 ##
  23 import logging
  24
  25 import requests
  26
  27 from osm_mon.core.config import Config
  28 from osm_mon.evaluator.backends.base import BaseBackend
  29
  30 log = logging.getLogger(__name__)
  31
  32 OSM_METRIC_PREFIX = 'osm_'
  33
  34
  35 class PrometheusBackend(BaseBackend):
  36
  37     def __init__(self, config: Config):
  38         super().__init__(config)
  39         self.conf = config
  40
  41     def get_metric_value(self, metric_name: str, tags: dict):
  42         query = self._build_query(metric_name, tags)
  43         request_url = self._build_url(query)
  44         log.info("Querying Prometheus: %s", request_url)
  45         r = requests.get(request_url, timeout=int(self.conf.get('global', 'request_timeout')))
  46         if r.status_code == 200:
  47             json_response = r.json()
  48             if json_response['status'] == 'success':
  49                 return self._get_metric_value_from_response(json_response)
  50             else:
  51                 log.warning("Prometheus response is not success. Got status %s", json_response['status'])
  52         else:
  53             log.warning("Error contacting Prometheus. Got status code %s: %s", r.status_code, r.text)
  54         return None
  55
  56     def _build_query(self, metric_name: str, tags: dict) -> str:
  57         query_section_tags = []
  58         for k, v in tags.items():
  59             query_section_tags.append(k + '=\"' + v + '\"')
  60         query_section = "query={0}{{{1}}}".format(OSM_METRIC_PREFIX + metric_name, ','.join(query_section_tags))
  61         return query_section
  62
  63     def _build_url(self, query: str):
  64         return self.conf.get('prometheus', 'url') + "/api/v1/query?" + query
  65
  66     def _get_metric_value_from_response(self, json_response):
  67         result = json_response['data']['result']
  68         if len(result):
  69             metric_value = float(result[0]['value'][1])
  70             log.info("Metric value: %s", metric_value)
  71             return metric_value
  72         else:
  73             return None