Django+Celery+RabbitMQ

1. 需要在项目目录下创建一个新的celery.py文件（与setting.py同级）

   # celery.py
   from celery import Celery
   
   # Set the default Django settings module for the 'celery' program.
   os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'proj.settings')
   
   app = Celery('proj')
   
   # Using a string here means the worker doesn't have to serialize
   # the configuration object to child processes.
   # - namespace='CELERY' 所有和Celery相关的配置需要前缀为CELERY_,防止与Django的配置重叠
   app.config_from_object('django.conf:settings', namespace='CELERY')
   
   # 将来自Django应用的任务自动注册到Celery中
   app.autodiscover_tasks()
   """
   应用中有tasks.py就能自动发现
   - app1/
       - tasks.py
       - models.py
   - app2/
       - tasks.py
       - models.py
   """
   
   
   @app.task(bind=True)
   def debug_task(self):
       print(f'Request: {self.request!r}')
   

   # settings.py
   # Celery Configuration Options
   CELERY_TIMEZONE = "Australia/Tasmania"
   CELERY_TASK_TRACK_STARTED = True
   CELERY_TASK_TIME_LIMIT = 30 * 60
   

2. 需要在项目目录下个的_init.py_.py中导入这个应用程序，一遍@shared_task装饰器使用

   from .celery import app as celery_app
   
   __all__ = ('celery_app',) 
   

3. 在各应用中的tasks.py中使用的装饰器是@shared_task，而不是@app.task

4. django-celery-results，使用Django ORM/Cache作为结果后端

   1. pip install django-celery-results

   2. # settings.py
      INSTALLED_APPS = (
          ...,
          'django_celery_results',	# 注意此处是下划线
      )
      
      # CELERY_RESULT_BACKEND = 'django-db'
      CELERY_CACHE_BACKEND = 'default'
      CACHES = {
          'default': {
              'BACKEND': 'django.core.cache.backends.db.DatabaseCache',
              'LOCATION': 'my_cache_table',
          }
      }
      

   3. 通过执行数据库迁移来创建 Celery 数据库表

      python manage.py migrate django_celery_results
      

5. django-celery-beats，管理定期任务

   1. pip install django-celery-beats

   # setting.py
   INSTALLED_APPS = (
       ...,
       'django_celery_beat',
   )
   

   python manage.py migrate
   celery -A proj beat -l INFO --scheduler django_celery_beat.schedulers:DatabaseScheduler
   

6. 启动工作进程

   python manage.py celery -A proj worker -l INFO
   

7. 示例

   # blog/models.py
   from django.db import models
   from django.utils.translation import ugettext_lazy as _
   
   
   class Comment(models.Model):
       name = models.CharField(_('name'), max_length=64)
       email_address = models.EmailField(_('email address'))
       homepage = models.URLField(_('home page'),
                                  blank=True, verify_exists=False)
       comment = models.TextField(_('comment'))
       pub_date = models.DateTimeField(_('Published date'),
                                       editable=False, auto_add_now=True)
       is_spam = models.BooleanField(_('spam?'),
                                     default=False, editable=False)
   
       class Meta:
           verbose_name = _('comment')
           verbose_name_plural = _('comments')
   

   # blog/views.py
   from django.http import HttpResponseRedirect
   from django.template.context import RequestContext
   from django.shortcuts import get_object_or_404, render_to_response
   
   from blog import tasks
   from blog.models import Comment
   
   
   class CommentForm(forms.ModelForm):
   
       class Meta:
           model = Comment
   
   
   def add_comment(request, slug, template_name='comments/create.html'):
       post = get_object_or_404(Entry, slug=slug)
       remote_addr = request.META.get('REMOTE_ADDR')
   
       if request.method == 'post':
           form = CommentForm(request.POST, request.FILES)
           if form.is_valid():
               comment = form.save()
               # 异步检查垃圾邮件
               tasks.spam_filter.delay(comment_id=comment.id,
                                       remote_addr=remote_addr)
               return HttpResponseRedirect(post.get_absolute_url())
       else:
           form = CommentForm()
   
       context = RequestContext(request, {'form': form})
       return render_to_response(template_name, context_instance=context)
   

   # blog/tasks.py
   from celery import Celery,shared_task
   
   from akismet import Akismet
   
   from django.core.exceptions import ImproperlyConfigured
   from django.contrib.sites.models import Site
   
   from blog.models import Comment
   
   
   app = Celery(broker='amqp://')
   
   
   @shared_task
   def spam_filter(comment_id, remote_addr=None):
       logger = spam_filter.get_logger()
       logger.info('Running spam filter for comment %s', comment_id)
   
       comment = Comment.objects.get(pk=comment_id)
       current_domain = Site.objects.get_current().domain
       akismet = Akismet(settings.AKISMET_KEY, 'http://{0}'.format(domain))
       if not akismet.verify_key():
           raise ImproperlyConfigured('Invalid AKISMET_KEY')
   
   
       is_spam = akismet.comment_check(user_ip=remote_addr,
                           comment_content=comment.comment,
                           comment_author=comment.name,
                           comment_author_email=comment.email_address)
       if is_spam:
           comment.is_spam = True
           comment.save()
   
       return is_spam