Celery & Async Tasks

Overview

Celery runs alongside Django using Redis as both the message broker and result backend. django-celery-beat stores periodic task schedules in the database so they can be managed via the Django admin.

Services

Service	Role
celery_worker	Executes tasks
celery_beat	Enqueues periodic tasks on schedule
redis	Broker + result backend

Common Task Types

• Email dispatch: welcome emails, password resets, assignment notifications (SendGrid via django-anymail)
• PDF generation: WeasyPrint renders filled form data into PDFs, then uploads to S3
• Digital signing: pyHanko applies signatures to completed PDFs
• Background check polling: periodic checks against Clearchecks API to update application status
• Scheduled reminders: competency test expiry warnings, document deadline alerts

Running Workers Locally

Docker Compose starts workers automatically. To run manually:

# Worker
docker compose run --rm celery_worker celery -A config worker -l info

# Beat scheduler
docker compose run --rm celery_beat celery -A config beat -l info --scheduler django_celery_beat.schedulers:DatabaseScheduler

Monitoring

Check task history and scheduled tasks via Django admin at /admin/django_celery_beat/ and /admin/django_celery_results/.