Celery，Django和Scrapy：从django应用程序导入时出错

时间：2016-01-06 03:28:54

标签： python django scrapy celery django-celery

我使用celery（和django-celery）允许用户通过django admin启动定期抓取。这是一个更大的项目的一部分，但我把这个问题简化为一个最小的例子。

首先，celery / celerybeat正在运行daemonized。如果我用我的django项目目录中的celery -A evofrontend worker -B -l info运行它们，那么我没有问题奇怪。

当我将celery / celerybeat作为守护进程运行时，我得到一个奇怪的导入错误：

[2016-01-06 03:05:12,292: ERROR/MainProcess] Task evosched.tasks.scrapingTask[e18450ad-4dc3-47a0-b03d-4381a0e65c31] raised unexpected: ImportError('No module named myutils',)
Traceback (most recent call last):
  File "/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages/celery/app/trace.py", line 240, in trace_task
    R = retval = fun(*args, **kwargs)
  File "/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages/celery/app/trace.py", line 438, in __protected_call__
    return self.run(*args, **kwargs)
  File "evosched/tasks.py", line 35, in scrapingTask
    cs = CrawlerScript('TestSpider', scrapy_settings)
  File "evosched/tasks.py", line 13, in __init__
    self.crawler = CrawlerProcess(scrapy_settings)
  File "/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages/scrapy/crawler.py", line 209, in __init__
    super(CrawlerProcess, self).__init__(settings)
  File "/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages/scrapy/crawler.py", line 115, in __init__
    self.spider_loader = _get_spider_loader(settings)
  File "/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages/scrapy/crawler.py", line 296, in _get_spider_loader
    return loader_cls.from_settings(settings.frozencopy())
  File "/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages/scrapy/spiderloader.py", line 30, in from_settings
    return cls(settings)
  File "/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages/scrapy/spiderloader.py", line 21, in __init__
    for module in walk_modules(name):
  File "/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages/scrapy/utils/misc.py", line 71, in walk_modules
    submod = import_module(fullpath)
  File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "retail/spiders/Retail_spider.py", line 16, in <module>
ImportError: No module named myutils

即。尽管将相关内容添加到syslog并执行django.setup()，但蜘蛛仍然无法从django项目应用程序导入。

我的预感是，这可能是由一个＆＃34;循环导入＆＃34;在初始化期间，但我不确定（有关相同错误的说明，请参阅here）

Celery守护进程配置

为了完整性，celeryd和celerybeat配置脚本是：

# /etc/default/celeryd
CELERYD_NODES="worker1"

CELERY_BIN="/home/lee/Desktop/pyco/evo-scraping-min/venv/bin/celery"

CELERY_APP="evofrontend"
DJANGO_SETTINGS_MODULE="evofrontend.settings"

CELERYD_CHDIR="/home/lee/Desktop/pyco/evo-scraping-min/evofrontend"

CELERYD_OPTS="--concurrency=1"

# Workers should run as an unprivileged user.
CELERYD_USER="lee"
CELERYD_GROUP="lee"

CELERY_CREATE_DIRS=1

和

# /etc/default/celerybeat 
CELERY_BIN="/home/lee/Desktop/pyco/evo-scraping-min/venv/bin/celery"

CELERY_APP="evofrontend"
CELERYBEAT_CHDIR="/home/lee/Desktop/pyco/evo-scraping-min/evofrontend/"

# Django settings module
export DJANGO_SETTINGS_MODULE="evofrontend.settings"

它们主要基于the generic ones，在我的virtualenv而不是系统中抛出Django设置并使用celery bin。

我还使用了the generic ones的init.d脚本。

项目结构

至于项目：它住在/home/lee/Desktop/pyco/evo-scraping-min。其下的所有文件都拥有所有权lee:lee。 dir包含Scrapy（evo-retail）和Django（evofrontend）项目，它们都在它下面，完整的树结构看起来像

├── evofrontend
│   ├── db.sqlite3
│   ├── evofrontend
│   │   ├── celery.py
│   │   ├── __init__.py
│   │   ├── settings.py
│   │   ├── urls.py
│   │   └── wsgi.py
│   ├── evosched
│   │   ├── __init__.py
│   │   ├── myutils.py
│   │   └── tasks.py
│   └── manage.py
└── evo-retail
    └── retail
        ├── logs
        ├── retail
        │   ├── __init__.py
        │   ├── settings.py
        │   └── spiders
        │       ├── __init__.py
        │       └── Retail_spider.py
        └── scrapy.cfg

Django项目相关文件

现在相关文件：evofrontend/evofrontend/celery.py看起来像

# evofrontend/evofrontend/celery.py
from __future__ import absolute_import
import os
from celery import Celery

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'evofrontend.settings')

from django.conf import settings

app = Celery('evofrontend')

# Using a string here means the worker will not have to
# pickle the object when using Windows.
app.config_from_object('django.conf:settings')
app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)

Django设置文件evofrontend/evofrontend/settings.py中可能相关的设置是

import os
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
PROJECT_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir))

INSTALLED_APPS = (
    ...
    'djcelery',
    'evosched',
)

# Celery settings
BROKER_URL = 'amqp://guest:guest@localhost//'
CELERY_ACCEPT_CONTENT = ['json']
CELERY_TASK_SERIALIZER = 'json'
CELERY_RESULT_SERIALIZER = 'json'
CELERY_TIMEZONE = 'Europe/London'
CELERYD_MAX_TASKS_PER_CHILD = 1  # Each worker is killed after one task, this prevents issues with reactor not being restartable
# Use django-celery backend database
CELERY_RESULT_BACKEND = 'djcelery.backends.database:DatabaseBackend'
# Set periodic task
CELERYBEAT_SCHEDULER = "djcelery.schedulers.DatabaseScheduler"

调度应用中的tasks.py evosched看起来像（它只是在更改目录后使用相关设置启动Scrapy蜘蛛）

# evofrontend/evosched/tasks.py
from __future__ import absolute_import
from celery import shared_task
from celery.utils.log import get_task_logger
logger = get_task_logger(__name__)
import os
from scrapy.crawler import CrawlerProcess
from scrapy.utils.project import get_project_settings
from django.conf import settings as django_settings


class CrawlerScript(object):
    def __init__(self, spider, scrapy_settings):
        self.crawler = CrawlerProcess(scrapy_settings)
        self.spider = spider  # just a string

    def run(self, **kwargs):
        # Pass the kwargs (usually command line args) to the crawler
        self.crawler.crawl(self.spider, **kwargs)
        self.crawler.start()


@shared_task
def scrapingTask(**kwargs):

    logger.info("Start scrape...")

    # scrapy.cfg file here pointing to settings...
    base_dir = django_settings.BASE_DIR
    os.chdir(os.path.join(base_dir, '..', 'evo-retail/retail'))
    scrapy_settings = get_project_settings()

    # Run crawler
    cs = CrawlerScript('TestSpider', scrapy_settings)
    cs.run(**kwargs)

evofrontend/evosched/myutils.py只包含（在此最小示例中）：

 # evofrontend/evosched/myutils.py
 SCRAPY_XHR_HEADERS = 'SOMETHING'

Scrapy项目相关文件

在完整的Scrapy项目中，设置文件看起来像

# evo-retail/retail/retail/settings.py
BOT_NAME = 'retail'

import os
PROJECT_ROOT = os.path.dirname(os.path.abspath(__file__))

SPIDER_MODULES = ['retail.spiders']
NEWSPIDER_MODULE = 'retail.spiders'

和（在这个最小的例子中）蜘蛛只是

# evo-retail/retail/retail/spiders/Retail_spider.py
from scrapy.conf import settings as scrapy_settings
from scrapy.spiders import Spider
from scrapy.http import Request
import sys
import django
import os
import posixpath
SCRAPY_BASE_DIR = scrapy_settings['PROJECT_ROOT']
DJANGO_DIR = posixpath.normpath(os.path.join(SCRAPY_BASE_DIR, '../../../', 'evofrontend'))
sys.path.insert(0, DJANGO_DIR)
os.environ.setdefault("DJANGO_SETTINGS_MODULE", 'evofrontend.settings')
django.setup()
from evosched.myutils import SCRAPY_XHR_HEADERS

class RetailSpider(Spider):

    name = "TestSpider"

    def start_requests(self):
        print SCRAPY_XHR_HEADERS
        yield Request(url='http://www.google.com', callback=self.parse)

    def parse(self, response):
        print response.url
        return []

修改

我通过大量的反复试验发现，如果我尝试导入的应用程序位于我的INSTALLED_APPS django设置中，那么它会因导入错误而失败，但是如果我从然后我不再得到导入错误（例如从evosched删除INSTALLED_APPS然后蜘蛛中的导入很好......）。显然不是解决方案，但可能是一个线索。

编辑2

我在蜘蛛失败导入之前立即打印sys.path，结果是

/home/lee/Desktop/pyco/evo-scraping-min/evofrontend/../evo-retail/retail 
/home/lee/Desktop/pyco/evo-scraping-min/venv/lib/python2.7
/home/lee/Desktop/pyco/evo-scraping-min/venv/lib/python2.7/plat-x86_64-linux-gnu
/home/lee/Desktop/pyco/evo-scraping-min/venv/lib/python2.7/lib-tk
/home/lee/Desktop/pyco/evo-scraping-min/venv/lib/python2.7/lib-old  
/home/lee/Desktop/pyco/evo-scraping-min/venv/lib/python2.7/lib-dynload
/usr/lib/python2.7
/usr/lib/python2.7/plat-x86_64-linux-gnu
/usr/lib/python2.7/lib-tk
/home/lee/Desktop/pyco/evo-scraping-min/venv/local/lib/python2.7/site-packages
/home/lee/Desktop/pyco/evo-scraping-min/evofrontend 
/home/lee/Desktop/pyco/evo-scraping-min/evo-retail/retail`

编辑3

如果我import evosched然后print dir(evosched)，我会看到＆＃34;任务＆＃34;如果我选择包含这样的文件，我也可以看到＆＃34; models＆＃34;，因此实际上可以从模型中导入。但是，我不会看到＆＃34; myutils＆＃34 ;.即使from evosched import myutils失败了，如果将语句放在下面的函数而不是全局函数中也会失败（我认为这可能会导致循环导入问题...）。直接import evosched有效......可能import evosched.utils可行。还没试过......

1 个答案:

答案 0 :(得分：0)

似乎celery守护程序正在使用系统的python而不是virtualenv中的python二进制文件。你需要使用

# Python interpreter from environment. 
ENV_PYTHON="$CELERYD_CHDIR/env/bin/python"

如前所述here告诉celeryd使用virtualenv中的python运行。

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