Migrate to controller-runtime logger

[tenzen-y]

Currently, the training-operator uses some types of logger like this:

• sirupsen/logrus logger:

  training-operator/pkg/util/logger.go

  Line 85 in c204220

  func LoggerForUnstructured(obj *metav1unstructured.Unstructured, kind string) *log.Entry {

• controller-runtime logger:

  training-operator/cmd/training-operator.v1/main.go

  Line 111 in c204220

  ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))

So, based on this discussion, I'd like to suggest using the controller-runtime logger everywhere to increase maintainability and consistency.

[champon1020]

Could I work on this task?

[tenzen-y]

@champon1020 Sure, Feel free to assign yourself with a /assign comment.

[champon1020]

/assign

[champon1020]

Sorry for the late action but I'm going to tackle this issue.
Then, I have two questions about design of implementation.

The logger, which is initialized by calling ctrl.SetLogger, can be referred by "sigs.k8s.io/controller-runtime/pkg/log".Log and each k8s controller has the logger reference in their structure.

training-operator/pkg/controller.v1/mpi/mpijob_controller.go

Line 109 in f3792b0

Log logr.Logger

So, I think we should pass the logger and attach key-values instead of returning new logger in the LoggerForXXX functions of commonutil pacakge.

func LoggerForUnstructured(logger logr.Logger, *metav1unstructured.Unstructured, kind string) logr.Logger {
  return logger.WithValues(...)
}

Also, Warning method of logrus.Logger is used sometimes but logr.Logger only has Info and Error methods.
While it could be possible to distinguish the log-level by using V method of logr.Logger, I think it is better to set rules for log-level numbers. (Alternatively, it would be possible to unify Info and Warning logs into Info)

Please let me know your opinions. (cc: @tenzen-y)