因最近想嘗試一下Python來對接微信公眾平臺，結合相對比較熟悉的tornado+celery+redis來實現一些特定的功能.

微信公眾平臺的很多接口調用依賴access_token，但是它只有2小時的有效期，因此需要定時去獲取有效的token.因此這里使用tornado的異步httpclient獲取數據，并將結果寫入redis 完成整個過程.

1.目錄結構

將任務定義與celery運行配置隔離開放在不同的文件中，

mytask
--celery.py
--celeryconfig.py
--task.py
--__init__.py

2.celery.py

#!/usr/bin/env python2.7
# -*- coding: utf-8 -*-

from __future__ import absolute_import  #當前文件名為celery，避免跟celery庫沖突

from celery import Celery,platforms

app = Celery('mytask', include=['mytask.task'])

app.config_from_object('mytask.celeryconfig')
platforms.C_FORCE_ROOT = True  #允許使用root執行

if __name__ == '__main__':
    app.start()

3.celeryconfig.py #每隔一段時間執行任務

#!/usr/bin/env python
# -*- coding:utf-8 -*-

#http://docs.celeryproject.org/en/latest/userguide/configuration.html#configuration
#celery 4.0開始引入了小寫字母的配置項[舊的大寫配置依然可以使用]

from __future__ import absolute_import

BROKER_URL = 'redis://localhost:6379/0'
CELERY_USER='work'
CELERY_GROUP='work'
CELERY_CREATE_DIRS=1
CELERY_LOG_FILE='/var/log/celery/%n%I.log'
CELERY_PID_FILE='/var/log/celery/%n.pid'

CELERY_TASK_SERIALIZER = ‘json’ # 4.0開始默認為JSON，此前為pickle

CELERY_ACCEPT_CONTENT = ['json']

CELERY_TIMEZONE = 'Asia/Shanghai'

from datetime import timedelta

CELERYBEAT_SCHEDULE = {
  'fetch-every-6000-seconds': {
    'task':'mytask.task.fetch_access_token’, #任務路徑
    'schedule': timedelta(seconds=6000) #每6000秒執行，access_token2小時過期，需要定時獲取，這里設置為100分鐘執行一次，測試時，可以調小，查看效果
  }
}

4.task.py

#!/usr/bin/env python2.7
# -*- coding: utf-8 -*-
from __future__ import absolute_import
import sys,json
from tornado import httpclient, gen, ioloop
import hashlib
import time
from celery import Celery
from tornado.options import define, options
import redis

base_config = {
    'AppID': 'wx*****',  #自行替換為微信公眾號接口AppID
    'AppSecret': '**********', #自行替換
    'redis': {
        'host': '127.0.0.1',
        'port': 6379
    },
    "user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36",
}

reload(sys)
sys.setdefaultencoding('utf8')

global_redis = redis.StrictRedis(host=base_config['redis']['host'], port=base_config['redis']['port'], db=0)

app = Celery()

@gen.coroutine
def main():
    base_url = 'https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=%s&secret=%s';

    http_header = {'User-Agent': base_config['user_agent'],
                       'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
                       'Accept-Encoding': 'gzip, deflate',
                       'Accept-Language': 'zh-CN,zh;q=0.8,en;q=0.6',
                       }

    httpclient.AsyncHTTPClient.configure(None,
                                            defaults=dict(user_agent=base_config["user_agent"]))

    url = base_url % (base_config['AppID'],base_config['AppSecret'])
    print url
    try:
        response = yield httpclient.AsyncHTTPClient().fetch(url, headers=http_header, method='GET')
    except web.HTTPError as e:
        print "tornado.web.HTTPError,", e.message
    finally:
        pass

    print('fetched %s' % url)

    html = response.body if isinstance(response.body, str) \
            else response.body.decode()
    final_rs = json.loads(html)
    try:
       new_access_token =  final_rs['access_token']
       global_redis.set('access_token',new_access_token);
       print "done,refresh new access token"
    except KeyError as e:
       print "return error", e.message
    finally:
        pass

#任務名稱
@app.task
def fetch_access_token():
    io_loop = ioloop.IOLoop.current()
    io_loop.run_sync(main)

5.執行：

$cd ./../ # cd到當前目錄上一級,不然找不到mytask
$celery -A mytask worker -B -l info  # -B 表示同時啟動beat調度器

6.改為crontab執行，修改celeryconfig.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from __future__ import absolute_import

BROKER_URL = 'redis://localhost:6379/0'
CELERY_USER='work'
CELERY_GROUP='work'
CELERY_CREATE_DIRS=1
CELERY_LOG_FILE='/var/log/celery/%n%I.log'
CELERY_PID_FILE='/var/log/celery/%n.pid'

CELERY_TASK_SERIALIZER = 'json'

CELERY_ACCEPT_CONTENT = ['json']

CELERY_TIMEZONE = 'Asia/Shanghai'

from celery.schedules import crontab

CELERYBEAT_SCHEDULE = {
  'fetch-every-6000-seconds': {
    'task':'mytask.task.fetch_access_token’, //任務路徑
    'schedule': crontab(hour=7, mintue=30, day_of_week=1) # 每周一早上7；30執行
  }
}

7.使用supervisord 管理celery

[program:celery]
user=work
numprocs=1
command=/usr/local/bin/celery -A mytask worker -B -l info
directory=/usr/local/htdocs   #mytask目錄部署在/usr/local/htdocs下
stdout_logfile=/tmp/supervisord_celery.log
autostart=true
autorestart=true
redirect_stderr=true
stopsignal=QUIT