That’s because you have not added yet any metadata. There are two types of meta data that you can set, the first one is static and the other one is dynamic.
Static Metadata
Aims to be used to send information that you know it won’t change on each static packet sent from gateway to chirpstack infra.
For example if you have a serial number as it’s stated in official documentation you can add within meta_data.static at your toml configuration the following:
serial_number="A1B21234"
Producing this at application server:
Dynamic Metadata
When you want to send information that changes over time which is your case.
For that, you must configure where the script is located in meta_data.dynamic.commands at your toml configuration.
temperature="python /opt/gateway-temperature/gateway-temperature.py"
You must in addition define the timeout to wait for the script to throw something into stdout and the execution interval which is the period at which the script should be executed over time.
Results will be similar to those as you would use for static metadata.