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     def __init__(self, config: Config):
  37         super().__init__(config)
  38         self.conf = config
  39
  40     def get_metric_value(self, metric_name: str, tags: dict):
  41         query = self._build_query(metric_name, tags)
  42         request_url = self._build_url(query)
  43         log.info("Querying Prometheus: %s", request_url)
  44         r = requests.get(
  45             request_url, timeout=int(self.conf.get("global", "request_timeout"))
  46         )
  47         if r.status_code == 200:
  48             json_response = r.json()
  49             if json_response["status"] == "success":
  50                 return self._get_metric_value_from_response(json_response)
  51             else:
  52                 log.warning(
  53                     "Prometheus response is not success. Got status %s",
  54                     json_response["status"],
  55                 )
  56         else:
  57             log.warning(
  58                 "Error contacting Prometheus. Got status code %s: %s",
  59                 r.status_code,
  60                 r.text,
  61             )
  62         return None
  63
  64     def _build_query(self, metric_name: str, tags: dict) -> str:
  65         query_section_tags = []
  66         for k, v in tags.items():
  67             query_section_tags.append(k + '="' + v + '"')
  68         query_section = "query={0}{{{1}}}".format(
  69             OSM_METRIC_PREFIX + metric_name, ",".join(query_section_tags)
  70         )
  71         return query_section
  72
  73     def _build_url(self, query: str):
  74         return self.conf.get("prometheus", "url") + "/api/v1/query?" + query
  75
  76     def _get_metric_value_from_response(self, json_response):
  77         result = json_response["data"]["result"]
  78         if len(result):
  79             metric_value = float(result[0]["value"][1])
  80             log.info("Metric value: %s", metric_value)
  81             return metric_value
  82         else:
  83             return None