How to load balance containers?
Put a load balancer, such as haproxy or nginx can even do the job.
Either way, put the load balancer on the host or on a different server that can access the exposed ports on the containers. Nginx will probably be simpler for your needs.
To setup basic nginx load balancing:
http {upstream myapp1 { server CONTAINER_APP0_IP:PORT; server CONTAINER_APP1_IP:PORT; server CONTAINER_APP2_IP:PORT;}server { listen 80; location / { proxy_pass http://myapp1; }}}