first commit

pkg/logger/logger.go

@@ -0,0 +1,53 @@
+package logger
+
+import (
+    "log"
+    "os"
+    "go.uber.org/zap"
+    "go.uber.go/zap/zapcore"
+)
+
+type Logger interface {
+	Debug(msg string, fields ...zap.Field)
+	Info(msg string, fields ...zap.Field)
+	Warn(msg string, fields ...zap.Field)
+	Error(msg string, fields ...zap.Field)
+	With(fields ...zap.Field) *zap.Logger
+}
+
+// Option is a function to provide the Logger creation with extra initialisation options.
+type Option func(*zap.Config)
+
+// init initializes zap's global loggers (i.e. zap.L() and zap.S()).
+// Log level is retrieved from environment variable LOG_LEVEL, defaulting to "info" otherwise.
+// To activate this facility, add a blank import to this package.
+func init() {
+	level := os.Getenv("LOG_LEVEL")
+	if level == "" {
+		level = "info"
+	}
+
+	initializeZapGlobals(level)
+}
+
+func initializeZapGlobals(level string) {
+	var zapLevel zapcore.Level
+	if err := zapLevel.UnmarshalText([]byte(level)); err != nil {
+		log.Fatalf("failed to parse logger level: %v", err)
+	}
+
+	log.Printf("setting logging level to '%s'.\n", zapLevel.String())
+
+	cfg := zap.NewProductionConfig()
+	cfg.Level = zap.NewAtomicLevelAt(zapLevel)
+	cfg.OutputPaths = []string{"stdout"}
+	cfg.ErrorOutputPaths = []string{"stderr"}
+	cfg.EncoderConfig.EncodeTime = zapcore.RFC3339NanoTimeEncoder
+
+	logger, err := cfg.Build()
+	if err != nil {
+		log.Fatalf("failed to initialize logger: %v", err)
+	}
+
+	zap.ReplaceGlobals(logger)
+}