send_task works only with a specific user - rabbitmq

Question

setup: Celery 4.1, RabbitMQ 3.6.1 (As broker), Redis (As backend, not relevant here).
Having two rabbit users:
admin_user with permissions of .* .* .*.
remote_user with permissions of ack ack ack.
admin_user can trigger tasks and is used by celery workers to handle tasks.
remote_user can only trigger one type of task - ack and is enqueued in a dedicated ack queue which later on being consumed by ack worker (by admin_user).
The remote_user sends the task by the following code:
from celery import Celery
app = Celery('remote', broker='amqp://remote_user:remote_pass#<machine_ip>:5672/vhost')
app.send_task('ack', args=('a1', 'a2'), queue='ack', route_name='ack')
This works perfectly in Celery 3.1. After upgrade to Celery 4.1 it doesn't send the task anymore. The call returns an AsyncResult but I don't see the message in Celery flower (or via rabbit management ui), or in the logs.
Trying to set permissions to remote_user .* .* .* as in the admin_user - doesn't help.
Trying to add administrator tag - doesn't help.
Changing the user of the broker to
'amqp://admin_user:admin_pass#<machine_ip>:5672/vhost' DOES work :
from celery import Celery
app = Celery('remote', broker='amqp://admin_user:admin_pass#<machine_ip>:5672/vhost')
app.send_task('ack', args=('a1', 'a2'), queue='ack', route_name='ack')
But I don't want to give a remote machine the admin_user permissions.
Any idea what I can do?

Answer 1

Solved,
API changed I guess, but to stay with the current permissions of RabbitMQ I had to use the following route:
old_celery_config.py: (celery 3.1)
CELERY_ROUTES = {
'ack_task': {
'queue': 'geo_ack'
}
}
celery_config.py: (celery 4.1)
CELERY_ROUTES = {
'ack_task': {
'exchange': 'ack',
'exchange_type': 'direct',
'routing_key': 'ack'
}
}
run_task.py:
from celery import Celery
app = Celery('remote', broker='amqp://remote_user:remote_pass#<machine_ip>:5672/vhost')
app.config_from_object('celery_config')
app.send_task('ack_task', args=('a1', 'a2'))