Sets up links for logs generated by a YARN application.
The logs for each container can be classified into one or more ways.
This allows us to easily focus on the logs of interest.
1. Host: Container ran on that host
2. Mapper: Container ran a map task
3. Reducer: Container ran a reduce task
So for a mapreduce app, the directory structure will look like this:
/path/to/log/dir/app_id/hosts
/path/to/log/dir/app_id/hosts/host1/container1/syslog
/path/to/log/dir/app_id/hosts/host1/container1/stdout
/path/to/log/dir/app_id/hosts/host1/container1/stderr
/path/to/log/dir/app_id/hosts/host2/container2/syslog
/path/to/log/dir/app_id/hosts/host2/container2/stdout
/path/to/log/dir/app_id/hosts/host2/container2/stderr
/path/to/log/dir/app_id/mappers
/path/to/log/dir/app_id/mappers/container1/syslog
/path/to/log/dir/app_id/mappers/container1/stdout
/path/to/log/dir/app_id/mappers/container1/stderr
/path/to/log/dir/app_id/reducers
/path/to/log/dir/app_id/reducers/container1/syslog
/path/to/log/dir/app_id/reducers/container1/stdout
/path/to/log/dir/app_id/reducers/container1/stderr