func InitMetrics(appID string) error {
	if err := DefaultMonitoring.Init(appID); err != nil {
		return err
	}
	if err := DefaultGRPCMonitoring.Init(appID); err != nil {
		return err
	}
	if err := DefaultHTTPMonitoring.Init(appID); err != nil {
		return err
	}
	view.SetReportingPeriod(DefaultReportingPeriod)
	return nil
}
InitMetrics initializes metrics.
package diagnostics
import (
	"time"
	"go.opencensus.io/stats/view"
	"go.opencensus.io/tag"
)
var appIDKey = tag.MustNewKey("app_id")
var (
	DefaultReportingPeriod = 1 * time.Minute
	DefaultMonitoring = newServiceMetrics()
	DefaultGRPCMonitoring = newGRPCMetrics()
	DefaultHTTPMonitoring = newHTTPMetrics()
)