How to determine port in container_commands?

Is there any way to get the port that the application must bind in container_commands in Elastic Beanstalk?

The Java application that I'm trying to deploy uses a configuration file to determine the port it will bind and I'm using container_commands to create that file. However; it seems that PORT environment variable is not available in container_commands. It's is only available in Procfile but the application doesn't support VM options or program arguments.