Health App View

views.py

from collections import defaultdict

from django.views.generic.base import TemplateResponseMixin, View

from rest_framework import status
from annoying.functions import get_config
from redis import StrictRedis


__all__ = [
    'StatusQueueView',
]


class StatusQueueView(TemplateResponseMixin,
                      View):

    status_queue_template_name = 'health/status_queue.djhtml'

    def get(self, request):
        context = self._get_queue_context()
        queue_summary = context['queue_summary']
        if self._is_queue_size_within_range(queue_summary):
            return self.response_class(
                request=self.request,
                template=self.status_queue_template_name,
                context=context
            )
        return self.response_class(
            request=self.request,
            template=self.status_queue_template_name,
            context=context,
            status=status.HTTP_503_SERVICE_UNAVAILABLE
        )

    def _get_queue_context(self):
        queue_names = get_config('MOINITOR_QUEUES')
        queue_summary = self._get_queue_summary(queue_names)
        return {
            'queue_summary': dict(queue_summary)
        }

    def _is_queue_size_within_range(self, queue_summary):
        allowable_max_queue_size = get_config('ALLOWABLE_MAX_QUEUE_SIZE')
        for name, size in queue_summary.items():
            if size > allowable_max_queue_size:
                return False
        return True

    def get_queue_summary(self, queue_names, connection=None):
        """
        Gets the queue size for the specified `queue_names`.
        :queue_names: A list of queue names who's size
            has to be determined (required).
        :connection: The connection to the client where the queue
            is stored, defaults to redis.
        """
        connection = connection or StrictRedis.from_url(get_config('REDIS_URL'))
        summary = defaultdict(int)
        for queue_name in queue_names:
            summary[queue_name] = connection.llen(queue_name)
        return summary