python程序的热部署实现[通俗易懂]

# coding=utf-8
"""实现热更新功能"""
import importlib
import json
import sys
import threading
import logging

from hotupdate.hot_update import HotUpdateEventDriven, HotUpdateMessage

driven = HotUpdateEventDriven()


def _callback(ch, method, properties, body):
    """收到消息执行的回调函数"""
    try:
        msg = json.loads(body.decode('utf-8'))
        message = HotUpdateMessage(model_path=msg['model_path'], is_append_path=msg['is_append_path'], physical_path=msg['physical_path'])
        # 物理路径加入pythonPath中
        if message.is_append_path:
            sys.path.append(message.physical_path)

        # 动态的引入该模块
        import_module = importlib.import_module(message.model_path)
        reload(import_module)
        # 打印热更新信息
        logging.warning('%s模块已经更新' % (message.model_path))
    except Exception, e:
        logging.warning('热部署失败，收到的消息%s,异常信息%s' % (body, e.message))
    # 消息确认
    driven.input_channel.basic_ack(delivery_tag=method.delivery_tag)


def _run():
    """线程的执行方法"""
    driven.receive(_callback)


def auto_reload_module():
    """reload a module. 新开一个线程来进行reload操作 动态更新python模块代码，依赖事件驱动，就是需要有人或者程序发送消息通知程序 """
    t = threading.Thread(target=_run, name='autoReloadThread')
    t.start()

# encoding=utf-8
# ---------------------------------------
# 语言：Python2.7
# 功能：事件驱动，触发热部署动作
# ---------------------------------------
import uuid

import pika

from queues import queueBase
from settings import MQ


class HotUpdateEventDriven(object):
    """监听mq消息，收到消息，自动reload"""

    def __init__(self):
        credentials = pika.PlainCredentials(MQ['userName'], MQ['password'])
        parameters = pika.ConnectionParameters(MQ['host'], MQ['port'], '/', credentials=credentials)
        self.connection = pika.BlockingConnection(parameters)
        self.__init_input__()

    def __init_input__(self):
        ''' 初始化入口通道 '''
        self.input_channel = self.connection.channel()
        input_exchange = 'python.ppmoney.hotupdate'
        input_exchange_type = 'fanout'
        input_routing_key = '#'
        # 消息入口的队列
        self.input_queue = 'python.hotupdate.%s' % (uuid.uuid1())
        # 声明路由，如果存在就什么也不会做
        self.input_channel.exchange_declare(exchange=input_exchange, exchange_type=input_exchange_type, durable=True)
        # 声明队列
        self.input_channel.queue_declare(queue=self.input_queue, auto_delete=True)
        # 通过routing_key 将交换机与queue绑定起来
        self.input_channel.queue_bind(exchange=input_exchange, queue=self.input_queue, routing_key=input_routing_key)

    def receive(self, callback):
        ''' 入口通道：接受自动同步服务发送的任务消息 '''
        # 入口通道订阅消费者
        self.input_channel.basic_consume(consumer_callback=callback, queue=self.input_queue, consumer_tag='hotupdate_client')
        self.input_channel.start_consuming()


class HotUpdateMessage(object):
    """收到的mq消息"""

    def __init__(self, model_path, is_append_path, physical_path):
        # 模块名称
        self.model_path = model_path
        # 是否需要添加到pythonPath中
        self.is_append_path = is_append_path
        # 如果需要添加到PythonPath中，需要提供模块的物理路径
        self.physical_path = physical_path

# 开启热更新
hotupdate.auto_reload_module()