osm_lcm/prometheus.py

   1 # -*- coding: utf-8 -*-
   2
   3 ##
   4 # Copyright 2020 Telefonica S.A.
   5 #
   6 # Licensed under the Apache License, Version 2.0 (the "License"); you may
   7 # not use this file except in compliance with the License. You may obtain
   8 # a copy of the License at
   9 #
  10 #         http://www.apache.org/licenses/LICENSE-2.0
  11 #
  12 # Unless required by applicable law or agreed to in writing, software
  13 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  14 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  15 # License for the specific language governing permissions and limitations
  16 # under the License.
  17 ##
  18
  19 import asyncio
  20 from time import time
  21 import logging
  22 import aiohttp
  23 import yaml
  24 import os
  25 from osm_lcm.lcm_utils import LcmException
  26 from osm_common.dbbase import DbException
  27 from jinja2 import Template, TemplateError, TemplateNotFound, TemplateSyntaxError
  28
  29 __author__ = "Alfonso Tierno <alfonso.tiernosepulveda@telefonica.com>"
  30
  31 initial_prometheus_data = {
  32     "_id": "prometheus",
  33     "_admin": {
  34         "locked_at": 0,
  35         "locked_by": None,
  36         "modified": 1593445184,  # 2020-06-29
  37         "created": 1593445184,
  38         "version": "1.0"    # to allow future version updates
  39     },
  40     'scrape_configs': {   # Dictionary at database. Converted to list before sending to prometheus
  41         'mon_exporter': {'static_configs': [{'targets': ['mon:8000']}], 'job_name': 'mon_exporter'},
  42     },
  43     'global': {'evaluation_interval': '15s', 'scrape_interval': '15s'},
  44     'rule_files': None,
  45     'alerting': {'alertmanagers': [{'static_configs': [{'targets': None}]}]}
  46 }
  47
  48
  49 class Prometheus:
  50     """
  51     Implements a class to update Prometheus
  52     """
  53
  54     PROMETHEUS_LOCKED_TIME = 120
  55
  56     def __init__(self, config, worker_id, db, loop, logger=None):
  57         self.worker_id = worker_id
  58         self.db = db
  59         self.loop = loop
  60         self.logger = logger or logging.getLogger("lcm.prometheus")
  61         self.server = config["uri"]
  62         self.path = config["path"]
  63         if not self.path.endswith("/"):
  64             self.path += "/"
  65         self.cfg_file = self.path + "prometheus.yml"
  66         self.cfg_file_backup = self.path + "prometheus.yml-backup"
  67
  68     @staticmethod
  69     def parse_job(job_data: str, variables: dict) -> dict:
  70         try:
  71             template = Template(job_data)
  72             job_parsed = template.render(variables or {})
  73             return yaml.safe_load(job_parsed)
  74         except (TemplateError, TemplateNotFound, TemplateSyntaxError) as e:
  75             # TODO yaml exceptions
  76             raise LcmException("Error parsing Jinja2 to prometheus job. job_data={}, variables={}. Error={}".format(
  77                 job_data, variables, e))
  78
  79     async def start(self):
  80         for retry in range(4):
  81             try:
  82                 # self.logger("Starting prometheus ")
  83                 # read from database
  84                 prometheus_data = self.db.get_one("admin", {"_id": "prometheus"}, fail_on_empty=False)
  85                 if not prometheus_data:
  86                     self.logger.info("Init db.admin.prometheus content")
  87                     self.db.create("admin", initial_prometheus_data)
  88                 # send database config file to prometheus. Ignore loading errors, as prometheus may be starting
  89                 # but at least an initial configuration file is set
  90                 await self.update()
  91                 return
  92             except DbException as e:
  93                 if retry == 3:
  94                     raise LcmException("Max retries trying to init prometheus configuration: {}".format(e))
  95                 await asyncio.sleep(5, loop=self.loop)
  96
  97     async def update(self, add_jobs: dict = None, remove_jobs: list = None) -> bool:
  98         """
  99
 100         :param add_jobs: dictionary with {job_id_1: job_content, job_id_2: job_content}
 101         :param remove_jobs: list with jobs to remove [job_id_1, job_id_2]
 102         :return: result. If false prometheus denies this configuration. Exception on error
 103         """
 104         for retry in range(4):
 105             result = True
 106             if retry:  # first time do not wait
 107                 await asyncio.sleep(self.PROMETHEUS_LOCKED_TIME / 2, loop=self.loop)
 108
 109             # lock database
 110             now = time()
 111             if not self.db.set_one(
 112                     "admin",
 113                     q_filter={"_id": "prometheus", "_admin.locked_at.lt": now - self.PROMETHEUS_LOCKED_TIME},
 114                     update_dict={"_admin.locked_at": now, "_admin.locked_by": self.worker_id},
 115                     fail_on_empty=False):
 116                 continue
 117             # read database
 118             prometheus_data = self.db.get_one("admin", {"_id": "prometheus"})
 119             update_dict = {"_admin.locked_at": 0,
 120                            "_admin.locked_by": None}
 121
 122             # Make changes from prometheus_incremental
 123             push_dict = pull_dict = None
 124             if add_jobs or remove_jobs:
 125                 log_text_list = []
 126                 if add_jobs:
 127                     log_text_list.append("adding jobs: {}".format(list(add_jobs.keys())))
 128                     prometheus_data["scrape_configs"].update(add_jobs)
 129                     push_dict = {"scrape_configs." + job_id: job_data for job_id, job_data in add_jobs.items()}
 130                 elif remove_jobs:
 131                     log_text_list.append("removing jobs: {}".format(list(remove_jobs)))
 132                     for job_id in remove_jobs:
 133                         prometheus_data["scrape_configs"].pop(job_id, None)
 134                     pull_dict = {"scrape_configs." + job_id: None for job_id in remove_jobs}
 135                 self.logger.debug(". ".join(log_text_list))
 136
 137             if not await self.send_data(prometheus_data):
 138                 push_dict = pull_dict = None
 139                 result = False
 140
 141             # unblock database
 142             if push_dict:
 143                 update_dict.update(push_dict)
 144             if push_dict or pull_dict:
 145                 update_dict["_admin.modified_at"] = now
 146             if not self.db.set_one(
 147                     "admin", {"_id": "prometheus", "_admin.locked_at": now, "_admin.locked_by": self.worker_id},
 148                     update_dict=update_dict, unset=pull_dict, fail_on_empty=False):
 149                 continue
 150             return result
 151         raise LcmException("Cannot update prometheus database. Reached max retries")
 152
 153     async def send_data(self, new_config):
 154         restore_backup = False
 155         del new_config["_id"]
 156         del new_config["_admin"]
 157         new_scrape_configs = []
 158
 159         # generate a list with the values of scrape_configs
 160         for scrape_config in new_config["scrape_configs"].values():
 161             scrape_config = scrape_config.copy()
 162             # remove nsr_id metadata from scrape_configs
 163             scrape_config.pop("nsr_id", None)
 164             new_scrape_configs.append(scrape_config)
 165         new_config["scrape_configs"] = new_scrape_configs
 166
 167         try:
 168             if os.path.exists(self.cfg_file):
 169                 os.rename(self.cfg_file, self.cfg_file_backup)
 170                 restore_backup = True
 171             with open(self.cfg_file, "w+") as f:
 172                 yaml.safe_dump(new_config, f, indent=4, default_flow_style=False)
 173             # self.logger.debug("new configuration: {}".format(yaml.safe_dump(new_config, indent=4,
 174             #                                                                 default_flow_style=False)))
 175             async with aiohttp.ClientSession() as session:
 176                 async with session.post(self.server + "-/reload") as resp:
 177                     if resp.status > 204:
 178                         raise LcmException(await resp.text())
 179                 await asyncio.sleep(5, loop=self.loop)
 180                 # If prometheus does not admit this configuration, remains with the old one
 181                 # Then, to check if the configuration has been accepted, get the configuration from prometheus
 182                 # and compares with the inserted one
 183                 async with session.get(self.server + "api/v1/status/config") as resp:
 184                     if resp.status > 204:
 185                         raise LcmException(await resp.text())
 186                     current_config = await resp.json()
 187                     if not self._check_configuration_equal(current_config, new_config):
 188                         return False
 189                     else:
 190                         restore_backup = False
 191             return True
 192         except Exception as e:
 193             self.logger.error("Error updating prometheus configuration url={}: {}".format(self.server, e))
 194             return False
 195         finally:
 196             if restore_backup:
 197                 try:
 198                     os.rename(self.cfg_file_backup, self.cfg_file)
 199                 except Exception as e:
 200                     self.logger.critical("Exception while rolling back: {}".format(e))
 201
 202     def _check_configuration_equal(self, current_config, expected_config):
 203         try:
 204             # self.logger.debug("Comparing current_config='{}' with expected_config='{}'".format(current_config,
 205             #                                                                                    expected_config))
 206             current_config_yaml = yaml.safe_load(current_config['data']['yaml'])
 207             current_jobs = [j["job_name"] for j in current_config_yaml["scrape_configs"]]
 208             expected_jobs = [j["job_name"] for j in expected_config["scrape_configs"]]
 209             return current_jobs == expected_jobs
 210         except Exception as e:
 211             self.logger.error("Invalid obtained prometheus status. Error: '{}'. Obtained data: '{}'".format(
 212                 e, current_config))
 213             # if format is not understood, cannot be compared, assume it is ok
 214             return True