python.d/python_modules/base.py

   1 # Description: base for netdata python.d plugins
   2 # Author: Pawel Krupa (paulfantom)
   3
   4 from time import time
   5 import sys
   6
   7
   8 class BaseService(object):
   9     """
  10     Prototype of Service class.
  11     Implemented basic functionality to run jobs by `python.d.plugin`
  12     """
  13     def __init__(self, configuration=None, name=None):
  14         """
  15         This needs to be initialized in child classes
  16         :param configuration: dict
  17         :param name: str
  18         """
  19         self.name = name
  20         if configuration is None:
  21             self.error("BaseService: no configuration parameters supplied. Cannot create Service.")
  22             raise RuntimeError
  23         else:
  24             self._extract_base_config(configuration)
  25             self.timetable = {}
  26             self.create_timetable()
  27             self.chart_name = ""
  28
  29     def _extract_base_config(self, config):
  30         """
  31         Get basic parameters to run service
  32         Minimum config:
  33             config = {'update_every':1,
  34                       'priority':100000,
  35                       'retries':0}
  36         :param config: dict
  37         """
  38         self.update_every = int(config['update_every'])
  39         self.priority = int(config['priority'])
  40         self.retries = int(config['retries'])
  41         self.retries_left = self.retries
  42
  43     def create_timetable(self, freq=None):
  44         """
  45         Create service timetable.
  46         `freq` is optional
  47         Example:
  48             timetable = {'last': 1466370091.3767564,
  49                          'next': 1466370092,
  50                          'freq': 1}
  51         :param freq: int
  52         """
  53         if freq is None:
  54             freq = self.update_every
  55         now = time()
  56         self.timetable = {'last': now,
  57                           'next': now - (now % freq) + freq,
  58                           'freq': freq}
  59
  60     @staticmethod
  61     def error(msg, exception=""):
  62         if exception != "":
  63             exception = " " + str(exception).replace("\n"," ")
  64         sys.stderr.write(str(msg)+exception+"\n")
  65         sys.stderr.flush()
  66
  67     def check(self):
  68         """
  69         check() prototype
  70         :return: boolean
  71         """
  72         self.error("Service " + str(self.__name__) + "doesn't implement check() function")
  73         return False
  74
  75     def create(self):
  76         """
  77         create() prototype
  78         :return: boolean
  79         """
  80         self.error("Service " + str(self.__name__) + "doesn't implement create() function?")
  81         return False
  82
  83     def update(self):
  84         """
  85         update() prototype
  86         :return: boolean
  87         """
  88         self.error("Service " + str(self.__name__) + "doesn't implement update() function")
  89         return False