Realtime progress tracking of celery tasks

I have a main celery task that starts multiple sub-tasks (thousands) doing multiple actions (same actions per sub-task).

What i want is, from the main celery task to track in real-time for each action, how many are done and how many have failed for each sub-task.

In summary!

Main task: receive list of objects, and a list of actions to do for each object.
For each object, a sub-task is started to perform the actions for the object.
The main task is finished when all the sub-tasks are finished

So i need to know from the main task the real-time progress of the sub-tasks.

The app i am developing is using django/angularJs, and i need to show the real-time progress asynchronously in the front-end.

I am new to celery, and i am confused and don't know how to implement this.

Any help would be appreciated. Thanks in advance.

I have done this before, there's too much code to put in here, so please allow me to simply put the outline, as I trust you can take care of the actual implementation and configuration:

Socket.io-based microservice to send real time events to browser

First, Django is synchronous, so it's not easy doing anything real time with it.

So I resorted to a socket.io process. You could say it's a microservice that only listens to a "channel" that was Redis-backed, and sends notifications to a browser client that listens to a given channel.

Celery -> Redis -> Socket.io -> Browser

I made it so each channel is identified with a Celery task ID. So when I fire a celery task from browser, I get the task ID, keep it and start listening to events from socket.io via that channel.

In chronological order it looks like this:

Fire off the Celery task, get the ID
Keep the ID in your client app, open a socket.io channel to listen for updates
The celery task sends messages to Redis, this will trigger socket.io events
Socket.io relays the messages to the browser, in real time

Reporting the progress

As for the actual updating of the status of the task, I just make it so that the Celery task, within its code, sends a message on Redis with something like e.g. {'done': 2, 'total_to_be_done': 10} (to represent a task that went through 2 out of 10 steps, a 20% progress, I prefer to send both numbers for better UI/UX)

import redis
redis_pub = redis.StrictRedis()
channel = 'task:<task_id>:progress'
redis_pub.publish(channel, json.dumps({'done': 2, 'total_to_be_done': 10}))

Find documentation for publishing messages on Redis with Python here