Add zap encoding configurable

Json encoding is the default zap encoding value and can not be changeable.
This PR enables configuring zap encoding to console via new flag `log-format`.

CHANGELOG-3.6.md

@@ -28,3 +28,7 @@ See [code changes](https://github.com/etcd-io/etcd/compare/v3.5.0...v3.6.0).
 - Package `mvcc/buckets` was moved to `storage/schema`
 - Package `wal` was moved to `storage/wal`
 - Package `datadir` was moved to `storage/datadir`
+
+### etcd server
+
+- Add [`etcd --log-format`](https://github.com/etcd-io/etcd/pull/13339) flag to support log format.

client/pkg/logutil/log_format.go

@@ -0,0 +1,31 @@
+// Copyright 2019 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logutil
+
+const (
+	JsonLogFormat    = "json"
+	ConsoleLogFormat = "console"
+)
+
+var DefaultLogFormat = JsonLogFormat
+
+// ConvertToZapFormat converts log level string to zapcore.Level.
+func ConvertToZapFormat(format string) string {
+	if format == ConsoleLogFormat {
+		return format
+	}
+
+	return DefaultLogFormat
+}

client/pkg/logutil/log_format_test.go

@@ -0,0 +1,35 @@
+// Copyright 2019 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logutil
+
+import "testing"
+
+func TestLogFormat(t *testing.T) {
+	tests := []struct {
+		given string
+		want  string
+	}{
+		{"json", JsonLogFormat},
+		{"console", ConsoleLogFormat},
+		{"", JsonLogFormat},
+	}
+
+	for i, tt := range tests {
+		got := ConvertToZapFormat(tt.given)
+		if got != tt.want {
+			t.Errorf("#%d: ConvertToZapFormat failure: want=%v, got=%v", i, tt.want, got)
+		}
+	}
+}

client/pkg/logutil/zap.go

@@ -31,7 +31,7 @@ var DefaultZapLoggerConfig = zap.Config{
 		Thereafter: 100,
 	},
 
-	Encoding: "json",
+	Encoding: ConvertToZapFormat(DefaultLogFormat),
 
 	// copied from "zap.NewProductionEncoderConfig" with some updates
 	EncoderConfig: zapcore.EncoderConfig{

server/embed/config.go

@@ -361,6 +361,8 @@ type Config struct {
 	Logger string `json:"logger"`
 	// LogLevel configures log level. Only supports debug, info, warn, error, panic, or fatal. Default 'info'.
 	LogLevel string `json:"log-level"`
+	// LogFormat set log encoding. Only supports json, console. Default is 'json'.
+	LogFormat string `json:"log-format"`
 	// LogOutputs is either:
 	//  - "default" as os.Stderr,
 	//  - "stderr" as os.Stderr,

server/embed/config_logging.go

@@ -106,6 +106,7 @@ func (cfg *Config) setupLogging() error {
 			copied.ErrorOutputPaths = errOutputPaths
 			copied = logutil.MergeOutputPaths(copied)
 			copied.Level = zap.NewAtomicLevelAt(logutil.ConvertToZapLevel(cfg.LogLevel))
+			copied.Encoding = logutil.ConvertToZapFormat(cfg.LogFormat)
 			if cfg.ZapLoggerBuilder == nil {
 				lg, err := copied.Build()
 				if err != nil {
@@ -130,10 +131,17 @@ func (cfg *Config) setupLogging() error {
 
 			lvl := zap.NewAtomicLevelAt(logutil.ConvertToZapLevel(cfg.LogLevel))
 
+			var encoder zapcore.Encoder
+			if logutil.ConvertToZapFormat(cfg.LogFormat) == logutil.ConsoleLogFormat {
+				encoder = zapcore.NewConsoleEncoder(logutil.DefaultZapLoggerConfig.EncoderConfig)
+			} else {
+				encoder = zapcore.NewJSONEncoder(logutil.DefaultZapLoggerConfig.EncoderConfig)
+			}
+
 			// WARN: do not change field names in encoder config
 			// journald logging writer assumes field names of "level" and "caller"
 			cr := zapcore.NewCore(
-				zapcore.NewJSONEncoder(logutil.DefaultZapLoggerConfig.EncoderConfig),
+				encoder,
 				syncer,
 				lvl,
 			)

server/etcdmain/config.go

@@ -247,6 +247,7 @@ func newConfig() *config {
 	fs.StringVar(&cfg.ec.Logger, "logger", "zap", "Currently only supports 'zap' for structured logging.")
 	fs.Var(flags.NewUniqueStringsValue(embed.DefaultLogOutput), "log-outputs", "Specify 'stdout' or 'stderr' to skip journald logging even when running under systemd, or list of comma separated output targets.")
 	fs.StringVar(&cfg.ec.LogLevel, "log-level", logutil.DefaultLogLevel, "Configures log level. Only supports debug, info, warn, error, panic, or fatal. Default 'info'.")
+	fs.StringVar(&cfg.ec.LogFormat, "log-format", logutil.DefaultLogFormat, "Configures log format. Only supports json, console. Default is 'json'.")
 	fs.BoolVar(&cfg.ec.EnableLogRotation, "enable-log-rotation", false, "Enable log rotation of a single log-outputs file target.")
 	fs.StringVar(&cfg.ec.LogRotationConfigJSON, "log-rotation-config-json", embed.DefaultLogRotationConfig, "Configures log rotation if enabled with a JSON logger config. Default: MaxSize=100(MB), MaxAge=0(days,no limit), MaxBackups=0(no limit), LocalTime=false(UTC), Compress=false(gzip)")
 

server/etcdmain/help.go

@@ -196,6 +196,8 @@ Logging:
     Specify 'stdout' or 'stderr' to skip journald logging even when running under systemd, or list of comma separated output targets.
   --log-level 'info'
     Configures log level. Only supports debug, info, warn, error, panic, or fatal.
+  --log-format 'json'
+    Configures log format. Only supports json, console.
   --enable-log-rotation 'false'
     Enable log rotation of a single log-outputs file target.
   --log-rotation-config-json '{"maxsize": 100, "maxage": 0, "maxbackups": 0, "localtime": false, "compress": false}'