No response after connecting from celery to redis

I'm following this tutorial, and adjusting the Celery-background related code to my project.

In my case I am operating in a Docker environment, and I have a secured site (i.e. https://localhost). which requires secured ssl communication.

I adjusted the code for secure connection.
I had initial connection problems, which created log error messages, but I was able to solve - see here.

Now the log file is quite, but I think that I still have connection problems. As a result, at runtime, when triggerring a task, nothing happens.

What could be the reason for no connection in the secured case?
Should I expect a message if the keys are incorrect? Is there a way to test the connection from celery/web containers to redis container from the command line?

I was able to fix the problem by making changes to the configuration of the containers.
Specifically, I made the following changes:

In redis container:

followed this tutorial to add stunnel, and create certs for the redis container
used this git code to configure stunnel within a Docker container

In celery container:
- elevated the log level to debug

I first tested that I can connect from my localhost to the redis docker container over ssl. This is described here

Then, I tested that I can connect from the celery container to the redis container over ssl. The docker-compose file is:

version: '3'

services:
  web:
    restart: always
    build:
      context: ./web
      dockerfile: Dockerfile
    expose:
      - "8000"
    volumes:
      - /home/webServer/web:/home/flask/app/web
      - /home/webServer/redis/ssl:/etc/certs
      - data2:/home/flask/app/web/project/img
    command: /usr/local/bin/gunicorn -w 2 -t 3600 -b :8000 project:app
    depends_on:
      - postgres
    stdin_open: true
    tty: true

  nginx:
    restart: always
    build:
      context: ./nginx
      dockerfile: Dockerfile
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - /home/webServer/web:/home/flask/app/web
      - data2:/home/flask/app/web/project/img
    depends_on:
      - web

  postgres:
    restart: always
    build:
      context: ./postgresql
      dockerfile: Dockerfile
    volumes:
      - data1:/var/lib/postgresql/data
    expose:
      - "5432"

  redis:
    build:
      context: ./redis
      dockerfile: Dockerfile
    restart: always

    command: sh -c "stunnel /stunnel-redis-server.conf && /usr/local/bin/redis-server /etc/redis/redis.conf"
    expose:
      - '6380'
    ports:
     - "6380:6380"
    volumes:
      - /home/webServer/redis/ssl:/etc/certs
      - /home/webServer/redis/conf:/etc/redis

  celery:
    build:
      context: ./web
    command: watchmedo auto-restart --directory=./ --pattern=*.py --recursive -- celery worker -A project.celery  --loglevel=debug
    volumes:
      - /home/webServer/web:/home/flask/app/web
      - /home/webServer/redis/ssl:/etc/certs
      - data2:/home/flask/app/web/project/img
    depends_on:
      - redis

volumes:
  data1:
  data2:

Other related files are:

files on the redis docker container: (the settings in these files are described here)

redis container Dockerfile
redis/conf/redis.conf
redis/stunnel-redis-server.conf

settings on the celery docker container:

cat web/project/flask_celery.py
...

key_file = '/etc/certs/localhost.key'
cert_file = '/etc/certs/private.pem'
ca_file = '/etc/certs/myCA.pem'
...    

celery = Celery(app.import_name,
                backend=app.config['CELERY_RESULT_BACKEND'],
                broker=app.config['CELERY_BROKER_URL'],
                broker_use_ssl = {
                    'ssl_keyfile': key_file,
                    'ssl_certfile': cert_file,
                    'ssl_ca_certs': ca_file,
                    'ssl_cert_reqs': ssl.CERT_REQUIRED
                },
                redis_backend_use_ssl = {
                    'ssl_keyfile': key_file,
                    'ssl_certfile': cert_file,
                    'ssl_ca_certs': ca_file,
                    'ssl_cert_reqs': ssl.CERT_REQUIRED
                })

------------------

cat project/__init__.py
...
app.config['CELERY_BROKER_URL'] = 'rediss://webserver_redis_1:6380/0'
app.config['CELERY_RESULT_BACKEND'] = 'rediss://webserver_redis_1:6380/0'