Applications in the same group can reach each other by application name and container port. For example, a web application can connect to database:5432 if the database listens there.
Internal connections
Use the destination application’s name, not localhost: inside a container, loopback refers to that container. The destination process must listen on an interface reachable from other containers, commonly 0.0.0.0.
Groups provide separate communication networks, not account permission isolation. Do not assume applications in different groups can use same-group name resolution.
Publish a port
Open application networking, choose TCP or UDP, and map a container port to an available public port. For Nginx, container port 80 can be published as TCP 8080.
Save, confirm running replicas, and test http://SERVER_IP:8080 for this HTTP example. Check cloud rules and host firewalls. An SSH tunnel must forward the application port separately from console port 9000.
A port mapping does not make the process listen or convert a TCP application into HTTP. Avoid conflicting public ports and expose only what clients need.
Domains and diagnostics
A domain route uses the application’s container port, without requiring a direct public mapping.
If a connection fails, check process logs, listening address, container port, group membership, task state, and server-to-server networking. For public access, additionally check the published protocol, public port, destination address, and firewall. See the networking FAQ for IPv6 and host networking issues.