Setting Logging Verbosity

Problem to solve

Right now you can't change the verbosity of your log files. There are settings available for:

# registry['log_level'] = "info"
# gitlab_shell['log_level'] = 'INFO'
# gitaly['logging_level'] = "warn"

But for the rest of our logging files we can't change them.

Further details

One of our customers (GitLab internal) wishes to take advantage of this feature.

Proposal

In the case of redis, there is a hardcoded loglevel variable that's set to notice. Changing this to a different level works, so it would be ideal if we could set its value dynamically via gitlab.rb

A similar approach for the rests of our services and its logs, and perhaps a setting for all logs to set them all in on setting.

Additionally, we could use the same naming convention for setting the log level per service, i.e. log_level.