Accessing container app from tty4

Hi there,
we have an multi-container setup for an app, playing multimedia content - this part work pretty well. We have also developed an controller app, that is intended to communicate with master process to query status, reset master process and so on. This app is meant to be accessible from tty4 console (ctrl+alt+F4)

Unfortunately I was unable to find out the way how to setup a container to output to tty4 on Balena.

Would anyone point us to right direction or give us an hint how to set this up?

Hello @simonahorakova first of all welcome to the balena community.

Could you please share more information about what device type are you using?
Could you please share more details about the controller app? is this a mobile app or similar? How do you connect this device with your balena device? USB?

did you check what is visible from /dev/tty... on the HostOS Terminal?

I will add the info. It’s an rpi with a display on HDMI.
Controll app displays output on console (on tty4 on development debian linux image). Output was visible on balena cloud.

I am sorry for late response - as mentioned by @jirinalepa - we need to present output visible on balena cloud terminal (stdout) on tty4

Any help appreciated

We are using whole scale RPIs 3-4.
The controller app is an console application that under normal circumstances presents its menu on stdout - this menu we need to be presented on tty4

There is nothing from the app visible on /dev/tty4 of HostOS, as we did not manage to find a way how to direct application menu to this device.

If you’re just looking at the output, wouldn’t something like <command> | tee /dev/tty4 work?

tee should then make your output go to both stdout (which shows up in balena logs) and /dev/tty4.

I’m not quite sure how this would go with reading the user inputs from /dev/tty4 though.
It would probably help to know more about how your controller app works regarding the I/O.