trace

type Span interface {
	End()

	// SetStatus sets the final status of the span.
	// errors passed to this should use interfaces defined in
	// github.com/virtual-kubelet/virtual-kubelet/errdefs
	//
	// If the error is nil, the span should be considered successful.
	SetStatus(err error)

	// WithField and WithFields adds attributes to an entire span
	//
	// This interface is a bit weird, but allows us to manage loggers in the context
	// It is expected that implementations set `log.WithLogger` so the logger stored
	// in the context is updated with the new fields.
	WithField(context.Context, string, interface{}) context.Context
	WithFields(context.Context, log.Fields) context.Context

	// Logger is used to log individual entries.
	// Calls to functions like `WithField` and `WithFields` on the logger should
	// not affect the rest of the span but rather individual entries.
	Logger() log.Logger
}

type Tracer interface {
	// StartSpan starts a new span. The span details are embedded into the returned
	// context
	StartSpan(context.Context, string) (context.Context, Span)
}