added logging configuration

README.md

@@ -155,6 +155,12 @@ For more details, see the examples.
 
 - [minimal](./examples/minimal/main.go): `go run ./examples/minimal`
 
+## Configuration
+
+### Logging
+The default format is generic JSON. The log format can be configured by setting the `LOG_FORMAT` environment variable. The supported formats are:
+- "stackdriver"
+- "console"
 
 ## Contributions
 

go.mod

@@ -1,6 +1,7 @@
 module github.com/voi-go/svc
 
 require (
+	github.com/blendle/zapdriver v1.3.1
 	github.com/caarlos0/env v3.5.0+incompatible
 	github.com/go-playground/locales v0.13.0 // indirect
 	github.com/go-playground/universal-translator v0.16.0 // indirect
@@ -9,7 +10,6 @@ require (
 	github.com/leodido/go-urn v1.2.0 // indirect
 	github.com/prometheus/client_golang v1.2.1
 	github.com/stretchr/testify v1.4.0
-	go.uber.org/atomic v1.4.0 // indirect
 	go.uber.org/multierr v1.2.0 // indirect
 	go.uber.org/zap v1.11.0
 	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect

go.sum

@@ -6,6 +6,8 @@ github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24
 github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/blendle/zapdriver v1.3.1 h1:C3dydBOWYRiOk+B8X9IVZ5IOe+7cl+tGOexN4QqHfpE=
+github.com/blendle/zapdriver v1.3.1/go.mod h1:mdXfREi6u5MArG4j9fewC+FGnXaBR+T4Ox4J2u4eHCc=
 github.com/caarlos0/env v3.5.0+incompatible h1:Yy0UN8o9Wtr/jGHZDpCBLpNrzcFLLM2yixi/rBrKyJs=
 github.com/caarlos0/env v3.5.0+incompatible/go.mod h1:tdCsowwCzMLdkqRYDlHpZCp2UooDD3MspDBjZ2AD02Y=
 github.com/cespare/xxhash/v2 v2.1.0 h1:yTUvW7Vhb89inJ+8irsUqiWjh8iT6sQPZiQzI6ReGkA=
@@ -83,8 +85,10 @@ github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJy
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 go.uber.org/atomic v1.4.0 h1:cxzIVoETapQEqDhQu3QfnvXAV4AlzcvUCxkVUFw3+EU=
 go.uber.org/atomic v1.4.0/go.mod h1:gD2HeocX3+yG+ygLZcrzQJaqmWj9AIm7n08wl/qW/PE=
+go.uber.org/multierr v1.1.0/go.mod h1:wR5kodmAFQ0UK8QlbwjlSNy0Z68gJhDJUG5sjR94q/0=
 go.uber.org/multierr v1.2.0 h1:6I+W7f5VwC5SV9dNrZ3qXrDB9mD0dyGOi/ZJmYw03T4=
 go.uber.org/multierr v1.2.0/go.mod h1:wR5kodmAFQ0UK8QlbwjlSNy0Z68gJhDJUG5sjR94q/0=
+go.uber.org/zap v1.10.0/go.mod h1:vwi/ZaCAaUcBkycHslxD9B2zi4UTXhF60s6SWpuDF0Q=
 go.uber.org/zap v1.11.0 h1:gSmpCfs+R47a4yQPAI4xJ0IPDLTRGXskm6UelqNXpqE=
 go.uber.org/zap v1.11.0/go.mod h1:vwi/ZaCAaUcBkycHslxD9B2zi4UTXhF60s6SWpuDF0Q=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=

logger.go

@@ -2,25 +2,51 @@ package svc
 
 import (
 	"os"
+	"strings"
 	"time"
 
+	"github.com/blendle/zapdriver"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 )
 
 func newLogger(name, version string, level zapcore.Level) (*zap.Logger, zap.AtomicLevel) {
+	logFormat := strings.ToLower(os.Getenv("LOG_FORMAT"))
+
 	atom := zap.NewAtomicLevel()
 	atom.SetLevel(level)
 
+	// stackdriver
+	if logFormat == "stackdriver" {
+		logger := zap.New(zapcore.NewSampler(zapcore.NewCore(
+			zapcore.NewJSONEncoder(zapdriver.NewProductionEncoderConfig()),
+			zapcore.Lock(os.Stdout),
+			atom,
+		), time.Second, 100, 10),
+			zap.ErrorOutput(zapcore.Lock(os.Stderr)),
+			zap.AddCaller(),
+		)
+		logger = logger.With(zapdriver.ServiceContext(name), zapdriver.Label("version", version))
+		return logger, atom
+	}
+
+	// console text logger or fallback to default generic JSON
+	var enc zapcore.Encoder
+	if logFormat == "console" {
+		config := zap.NewProductionEncoderConfig()
+		config.EncodeTime = zapcore.RFC3339TimeEncoder
+		enc = zapcore.NewConsoleEncoder(config)
+	} else {
+		enc = zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig())
+	}
 	logger := zap.New(zapcore.NewSampler(zapcore.NewCore(
-		zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig()),
+		enc,
 		zapcore.Lock(os.Stdout),
 		atom,
 	), time.Second, 100, 10),
 		zap.ErrorOutput(zapcore.Lock(os.Stderr)),
 		zap.AddCaller(),
 		zap.Fields(zap.String("app", name), zap.String("version", version)),
 	)
-
 	return logger, atom
 }