osm_common/msgkafka.py

   1 import logging
   2 import asyncio
   3 import yaml
   4 from aiokafka import AIOKafkaConsumer
   5 from aiokafka import AIOKafkaProducer
   6 from aiokafka.errors import KafkaError
   7 from osm_common.msgbase import MsgBase, MsgException
   8 # import json
   9
  10 __author__ = "Alfonso Tierno <alfonso.tiernosepulveda@telefonica.com>, " \
  11              "Guillermo Calvino <guillermo.calvinosanchez@altran.com>"
  12
  13
  14 class MsgKafka(MsgBase):
  15     def __init__(self, logger_name='msg'):
  16         self.logger = logging.getLogger(logger_name)
  17         self.host = None
  18         self.port = None
  19         self.consumer = None
  20         self.producer = None
  21         self.loop = None
  22         self.broker = None
  23
  24     def connect(self, config):
  25         try:
  26             if "logger_name" in config:
  27                 self.logger = logging.getLogger(config["logger_name"])
  28             self.host = config["host"]
  29             self.port = config["port"]
  30             self.loop = asyncio.get_event_loop()
  31             self.broker = str(self.host) + ":" + str(self.port)
  32
  33         except Exception as e:  # TODO refine
  34             raise MsgException(str(e))
  35
  36     def disconnect(self):
  37         try:
  38             pass
  39             # self.loop.close()
  40         except Exception as e:  # TODO refine
  41             raise MsgException(str(e))
  42
  43     def write(self, topic, key, msg):
  44         """
  45         Write a message at kafka bus
  46         :param topic: message topic, must be string
  47         :param key: message key, must be string
  48         :param msg: message content, can be string or dictionary
  49         :return: None or raises MsgException on failing
  50         """
  51         try:
  52             self.loop.run_until_complete(self.aiowrite(topic=topic, key=key, msg=msg))
  53
  54         except Exception as e:
  55             raise MsgException("Error writing {} topic: {}".format(topic, str(e)))
  56
  57     def read(self, topic):
  58         """
  59         Read from one or several topics.
  60         :param topic: can be str: single topic; or str list: several topics
  61         :return: topic, key, message; or None
  62         """
  63         try:
  64             return self.loop.run_until_complete(self.aioread(topic, self.loop))
  65         except MsgException:
  66             raise
  67         except Exception as e:
  68             raise MsgException("Error reading {} topic: {}".format(topic, str(e)))
  69
  70     async def aiowrite(self, topic, key, msg, loop=None):
  71
  72         if not loop:
  73             loop = self.loop
  74         try:
  75             self.producer = AIOKafkaProducer(loop=loop, key_serializer=str.encode, value_serializer=str.encode,
  76                                              bootstrap_servers=self.broker)
  77             await self.producer.start()
  78             await self.producer.send(topic=topic, key=key, value=yaml.safe_dump(msg, default_flow_style=True))
  79         except Exception as e:
  80             raise MsgException("Error publishing topic '{}', key '{}': {}".format(topic, key, e))
  81         finally:
  82             await self.producer.stop()
  83
  84     async def aioread(self, topic, loop=None, callback=None, *args):
  85         """
  86         Asyncio read from one or several topics. It blocks
  87         :param topic: can be str: single topic; or str list: several topics
  88         :param loop: asyncio loop
  89         :callback: callback function that will handle the message in kafka bus
  90         :*args: optional arguments for callback function
  91         :return: topic, key, message
  92         """
  93
  94         if not loop:
  95             loop = self.loop
  96         try:
  97             if isinstance(topic, (list, tuple)):
  98                 topic_list = topic
  99             else:
 100                 topic_list = (topic,)
 101
 102             self.consumer = AIOKafkaConsumer(loop=loop, bootstrap_servers=self.broker)
 103             await self.consumer.start()
 104             self.consumer.subscribe(topic_list)
 105
 106             async for message in self.consumer:
 107                 if callback:
 108                     callback(message.topic, yaml.load(message.key), yaml.load(message.value), *args)
 109                 else:
 110                     return message.topic, yaml.load(message.key), yaml.load(message.value)
 111         except KafkaError as e:
 112             raise MsgException(str(e))
 113         finally:
 114             await self.consumer.stop()