Otherwise only the ones listed in the environment: section will be included. I think it's safe to forward all of these, and I figure it's not worth individually listing every JSON config name here.
You might ask what the point of leaving COMM_MYSQL_DATABASE, COMM_MYSQL_USER and COMM_MYSQL_PASSWORD is. I figure it's better for discoverability to list these explicitly here, as they are required for the database to initialize and the Node keyserver to run.
Depends on D4173