How to get shell to a running custom linux container

I am developing a container launcher by referring to https://gist.github.com/zserge/4ce3c1ca837b96d58cc5bdcf8befb80e.

When I launch /sbin/init process using the container launcher I get the tty console for the same.I am implementing some application for my small hardware where I want to run this container at startup. I am able to launch the container at startup but its ttyS0 console get mixed with the ttyS0 console of my hardware.

1. I want to be able to attach a console to the running container similar to what we can do by lxc-attatch.
2. How should I make sure the container's "sbin/init" does not use ttyS0 and use some other tty

Edit:

1. I have my own rootfs similar to lxc container's.
2. My rootfs has /sbin/init process which I want to launch from this container launcher.