Proposal: better initialization of log verbosity level

[slintes]

Neither that important nor urgent, but this catched my eyes when looking into our logging implementation:

Currently we initialize both verbosityLevel and currentVerbosityLevel level to the same value, either what's given with the verbosity command line flag, or 0 [1].
Also, info level logs are actually logged when currentVerbosityLevel <= verbosityLevel [2]. That means as long as the V(currentVerbosityLevel) func isn't called, all Info(...) logs are always logged, even when the verbosity flag is specified with --v=0... not sure if that is what we want, and what the user expects.

Proposal:

• According to [3] verbosity level 2 is the "recommended default log level for most systems". So if no verbosity flag is specified, set verbosityLevel to 2.
• I think currentVerbosityLevel should be initialized indepent of verbosityLevel, always to the same value. A good value might be 2 or 3 (see [3]):
  • 2 means: "Useful steady state information about the service and important log messages that may correlate to significant changes in the system."
  • 3 means: "Extended information about changes. More info about system state changes."
    I'd propose to use 2, because
    • that would mean no change in behaviour compared to now when no verbosity flag is provided: Info(...) logs without V(...) will be logged because currentVerbosityLevel == verbosityLevel == 2.
    • if verbosity flag 0 or 1 is provided, you see less logs, which is very likely expected behaviour imho

Wdyt?

[1] https://github.com/kubevirt/kubevirt/blob/master/pkg/log/log.go#L97
[2] https://github.com/kubevirt/kubevirt/blob/master/pkg/log/log.go#L172
[3] https://github.com/kubernetes/community/blob/master/contributors/devel/logging.md