Details
Minor Description
Mesos includes various 3rd party libraries which use logging libraries other than glog. This means that glog-produced logs don't show a complete story – they lack messages from 3rd party libraries. The zookeeper library doesn't use glog, it logs to stdout/stderr and in a different format to the rest of Mesos, yet its logs are critical for troubleshooting production issues.
A complete story can be obtained by configuring Mesos to log to stdout/stderr – this captures and aggregates output from Mesos and its various libraries.
Mesos has support for viewing master/slave's logs from the web ui but the feature is only available when the --log_dir option is used. For the reasons above it's not always possible(/recommended) to use the option. It's also not possible to use the --log_dir option (eg, to be able to rotate logs) but disable log viewing in the web ui (eg, for security reasons).
Either the 3rd party libraries should be modified to use glog so there's a single logging framework (preferred), or Mesos should be modified so its web ui can serve an externally managed log.