The yarn-site.xml parameter 'yarn.nodemanager.log-dirs' can be a comma-separated list of paths (not according to the description in yarn-default.xml, but according to https://www.cloudera.com/documentation/enterprise/5-6-x/topics/cdh_sg_yarn_security.html).
On a cluster with such a configuration, I am not seeing the program.log file in the container log directory shown from the YARN UI. I do see stdout/stderr files there. I recall a gc.log file also.
In the container's data directory, the launch_container.sh file has an export of LOG_DIRS, which is also a comma-separated list of files, which seems to be the same as the value of 'yarn.nodemanager.local-dirs', but each element appended with the application and container ID of the container.
I believe this is causing some issue with the logback-container.xml configured.
No program.log file was found under any of the directories specified as LOG_DIRS.
The program.log file was found in a directory that was literally the value of 'yarn.nodemanager.log-dirs' (directories can have commas in them).