[MQTT] Client ID configuration

[VonOx]

I think we need to be able to change the client id in MQTT configuration.

Use case:
Single MQTT server with 2 Gladys containers ( Prod / Preprod )

Problem:
For now only one instance can be connected to mosquitto ( Connection is closed if same client id is used )

Logs:

1609587948: New connection from 192.168.1.42 on port 1883.
1609587948: Client gladys-assistant-main-instance already connected, closing old connection.
1609587948: New client connected from 192.168.1.42 as gladys-assistant-main-instance (p2, c1, k60, u'gladysmain').
1609587953: New connection from 192.168.1.42 on port 1883.
1609587953: Client gladys-assistant-main-instance already connected, closing old connection.
1609587953: New client connected from 192.168.1.42 as gladys-assistant-main-instance (p2, c1, k60, u'gladysdev').
1609587958: New connection from 192.168.1.42 on port 1883.

[Pierre-Gilles]

We could generate an ID to append at the end of the client_id to avoid that :)

[VonOx]

Client ID lenght must be limited in lenght ( MQTT Spec say 23 but majority of mqtt servers can handle more)
So I've used Math.random because uuid is too long

New client connected from 192.168.1.23 as gladys-main-instance-155267 (p2, c1, k60, u'gladysmain').

clientId: 'gladys-main-instance-'+ Math.floor(Math.random() * 1000000)

Do you agree ?

[Pierre-Gilles]

That's perfect!