Apologies in delayed response on this.
Currently you cannot set ACI hostnames manually and it is populated by the orchestrator under the hood. There is already a feature request here.
The possible workaround is to use a DNS name/Public IP & port combination (or masquerade them as environment variables with desired host names against each container separately) for inter container communication. More information in this document.
Other option could be:
If using docker compose applications by modifying /etc/hosts file which is shared by containers:
"You can also deploy and manage multi-container applications defined in Compose files to ACI using the docker compose command. All containers in the same Compose application are started in the same container group. Service discovery between the containers works using the service name specified in the Compose file. Name resolution between containers is achieved by writing service names in the /etc/hosts file that is shared automatically by all containers in the container group."
Refer this document.
Hope this information is helpful.
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