MQTT Client_host based on system variable

Hey just seeing if there was a way to set the MQTT in appdaemon.yaml via a system variable or another method? I’m currently running another bash script to do it but Ideally would like it done when building my docker-compose file.

The variable in question is client_host:

MQTT:
      client_host: xxx.xxx.xxx.xxx
      namespace: mqtt
      type: mqtt