clientv3: Bring back ETCD_CLIENT_DEBUG variable interpretation.

env ETCD_CLIENT_DEBUG supports log levels (debug, info, warn, error, dpanic, panic, fatal).
Only when set, overrides application-wide grpc logging settings.

pkg/logutil/log_level.go

@@ -15,9 +15,6 @@
 package logutil
 
 import (
-	"fmt"
-
-	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 )
 
@@ -25,22 +22,9 @@ var DefaultLogLevel = "info"
 
 // ConvertToZapLevel converts log level string to zapcore.Level.
 func ConvertToZapLevel(lvl string) zapcore.Level {
-	switch lvl {
-	case "debug":
-		return zap.DebugLevel
-	case "info":
-		return zap.InfoLevel
-	case "warn":
-		return zap.WarnLevel
-	case "error":
-		return zap.ErrorLevel
-	case "dpanic":
-		return zap.DPanicLevel
-	case "panic":
-		return zap.PanicLevel
-	case "fatal":
-		return zap.FatalLevel
-	default:
-		panic(fmt.Sprintf("unknown level %q", lvl))
+	var level zapcore.Level
+	if err := level.Set(lvl); err != nil {
+		panic(err)
 	}
+	return level
 }

pkg/logutil/zap_grpc.go

@@ -36,7 +36,7 @@ func NewGRPCLoggerV2(lcfg zap.Config) (grpclog.LoggerV2, error) {
 // if debug level is not enabled in "*zap.Logger".
 func NewGRPCLoggerV2FromZapCore(cr zapcore.Core, syncer zapcore.WriteSyncer) grpclog.LoggerV2 {
 	// "AddCallerSkip" to annotate caller outside of "logutil"
-	lg := zap.New(cr, zap.AddCaller(), zap.AddCallerSkip(1), zap.ErrorOutput(syncer))
+	lg := zap.New(cr, zap.AddCaller(), zap.AddCallerSkip(1), zap.ErrorOutput(syncer)).Named("grpc")
 	return &zapGRPCLogger{lg: lg, sugar: lg.Sugar()}
 }