Auto Discovery for MQTT Sensor Node (Ethernet)

I am working on implementing PoC of Temperature sensor node using Arduino Uno+Ethernet Shield and MQTT library. I am curious to know how the sensor node with MQTT can have auto discover and auto config feature. Imagine a scenario, if we have a customer which needs 100 quantity of these Temperature sensor nodes. I would prefer to have all sensor nodes with factory program (using one program). Customer may want to unpack the sensor, connect it and ready to use. It will great help if you can suggest how auto discover and config can be achieved for these sensor nodes.

Thanks, Anil