Celery + RabbitMQ => Stop/Reset schedule

[mrblacyk]

Create a Celery + RabbitMQ + PostgreSQL setup and integration with the project.

This must provide a robust scheduling system which can be cancelled. All the edgy cases should be handled (trying to cancel a task in a queue which was already cancelled, etc).

The idea is to provide a functionality to:

• Schedule a reset of a box with the ability to cancel the reset within 2 minutes.
• Schedule a shutoff of a box with the ability to cancel the shutdown within 2 minutes.

The code should call resetMachine and stopMachine from aplibvirt.py accordingly. The former is not yet defined and needs to be created (but in the worst case it can be similar to stopMachine), the latter is with the code of:

def stopMachine(
        virt_conn: libvirt.virConnect, domain_name: str) -> [int, bool]:
    """ Stop a domain by name
    Returns a list with:
    * an integer return code,
    * a boolean saying if the machine was already stopped.
"""

    virt_conn = reassureConnection(virt_conn)

    return _machineOperation(virt_conn, domain_name, "stop")

[mrblacyk]

Done in e786d18.

It's Celery + Redis. I will build an image soon-ish and push to Docker Hub.