第8章运维提升专题之部署篇

Nginx, WSGI, Flask之间的关系
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Nginx：Hey，WSGI，我刚收到了一个请求，我需要你作些准备，然后由Flask来处理这个请求。
WSGI：OK，Nginx。我会设置好环境变量，然后将这个请求传递给Flask处理。
Flask：Thanks WSGI！给我一些时间，我将会把请求的响应返回给你。
WSGI：Alright，那我等你。
Flask：Okay，我完成了，这里是请求的响应结果，请求把结果传递给Nginx。
WSGI：Good job！Nginx，这里是响应结果，已经按照要求给你传递回来了。
Nginx：Cool，我收到了，我把响应结果返回给客户端。大家合作愉快~

8-2 Django依赖服务的高可用

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自定义类，实现两种api的替换功能

import logging
import datetime

from thirdparty import juhe
from thirdparty.weather import heweather, CommonWeatherResult

logger = logging.getLogger('django')


class WeatherAPIProxy:
    @classmethod
    def ha_request(cls, cityname, timeout):
        try:
            data = juhe.weather(cityname, timeout)
        except Exception as e:
            logger.error("Request juhe weather API timeout. HARequest switch to hefeng weather.")
            data = heweather.HeWeather.get_weather(cityname, timeout)
        data = data.to_dict()
        return data


if __name__ == '__main__':
    print(WeatherAPIProxy.ha_request('北京', 1))

在view视图层调用api替换为能够实api代理池的类


class WeatherView(View, CommonResponseMixin):
    def get(self, request):
        if not utils.auth.already_authorized(request):
            response = self.wrap_json_response({}, code=ReturnCode.UNAUTHORIZED)
        else:
            data = []
            open_id = request.session.get('open_id')
            user = User.objects.filter(open_id=open_id)[0]
            cities = json.loads(user.focus_cities)
            for city in cities:
                # result = juhe.weather(city.get('city'))
                 result = WeatherAPIProxy.ha_request(city.get('city'),
                                                    timeout=settings.HA_TIMEOUT)
                result['city_info'] = city
                data.append(result)

            response = self.wrap_json_response(data=data, code=ReturnCode.SUCCESS)
        return JsonResponse(data=response, safe=False)

    def post(self, request):

        data = []
        received_body = request.body.decode('utf-8')
        received_body = json.loads(received_body)
        print(received_body)
        cities = received_body.get('cities')
        for city in cities:
            result = juhe.weather(city.get('city'))
            result['city_info'] = city
            data.append(result)
        response_data = self.wrap_json_response(data)
        return JsonResponse(data=response_data, safe=False)