I am new to MQTT. Is it possible to have an external IOT device that can publish it's readings in MQTT format and use the aedes MQTT broker node and a subscriber node in node-red that is installed in the IBM cloud environment to receive the payloads?
Currently I have a simple setup within node-red with the publish and subscribe nodes when using the 'localhost:1883' as a server address. Do I need to have a server with IP address to make this work?
Where do I start?
Short answer, no.
You can only access Node-RED running on IBM Cloud via HTTP/HTTPS, you will not be able to connect to the any broker you ran in the Node-RED process externally.
This is because the Node-RED instance is behind a reverse HTTP/HTTPS proxy.
You could deploy Node-RED in a Docker container or on a Virtual machine, or just make use of an external MQTT broker. But without a much better understanding of the whole problem you are trying to solve it is impossible to be more specific.