From 452a777f55f1d248bc393dd3d87dcba447f244a3 Mon Sep 17 00:00:00 2001
From: Sylvain Baubeau <lebauce@gmail.com>
Date: Mon, 30 Oct 2023 19:54:07 +0100
Subject: [PATCH] feat: create zap logger on demand

---
 pkg/log/lazy.go | 99 +++++++++++++++++++++++++++++++++++++++++++++++++
 pkg/log/log.go  | 15 ++++----
 2 files changed, 107 insertions(+), 7 deletions(-)
 create mode 100644 pkg/log/lazy.go

diff --git a/pkg/log/lazy.go b/pkg/log/lazy.go
new file mode 100644
index 00000000..b4a17597
--- /dev/null
+++ b/pkg/log/lazy.go
@@ -0,0 +1,99 @@
+package log
+
+import "go.uber.org/zap"
+
+type lazyLogger struct {
+	zapFactory func() (*zap.SugaredLogger, error)
+	zapLogger  *zap.SugaredLogger
+}
+
+// NewLazyLogger creates a new lazy logger with the specified function to call to create zap logger
+func NewLazyLogger(zapFactory func() (*zap.SugaredLogger, error)) lazyLogger {
+	return lazyLogger{zapFactory: zapFactory}
+}
+
+// ZapLogger creates a new zap logger if no logger was created yet
+func (l *lazyLogger) ZapLogger() *zap.SugaredLogger {
+	if l.zapLogger == nil {
+		l.zapLogger, _ = l.zapFactory() // no:lint: errcheck
+	}
+	return l.zapLogger
+}
+
+// Debug uses fmt.Sprint to construct and log a message.
+func (l *lazyLogger) Debug(args ...interface{}) {
+	l.ZapLogger().Debug(args...)
+}
+
+// Debugf uses fmt.Sprintf to log a templated message.
+func (l *lazyLogger) Debugf(template string, args ...interface{}) {
+	l.ZapLogger().Debugf(template, args...)
+}
+
+// Debugw logs a message with some additional context. The variadic key-value
+// pairs are treated as they are in With.
+//
+// When debug-level logging is disabled, this is much faster than
+//
+//	s.With(keysAndValues).Debug(msg)
+func (l *lazyLogger) Debugw(msg string, keysAndValues ...interface{}) {
+	l.ZapLogger().Debugw(msg, keysAndValues...)
+}
+
+// Info uses fmt.Sprint to log a templated message.
+func (l *lazyLogger) Info(args ...interface{}) {
+	l.ZapLogger().Info(args...)
+}
+
+// Infof uses fmt.Sprintf to log a templated message.
+func (l *lazyLogger) Infof(template string, args ...interface{}) {
+	l.ZapLogger().Infof(template, args...)
+}
+
+// Infow logs a message with some additional context. The variadic key-value
+// pairs are treated as they are in With.
+func (l *lazyLogger) Infow(msg string, keysAndValues ...interface{}) {
+	l.ZapLogger().Infow(msg, keysAndValues...)
+}
+
+// Warn uses fmt.Sprint to log a templated message.
+func (l *lazyLogger) Warn(args ...interface{}) {
+	l.ZapLogger().Warn(args...)
+}
+
+// Warnf uses fmt.Sprintf to log a templated message.
+func (l *lazyLogger) Warnf(template string, args ...interface{}) {
+	l.ZapLogger().Warnf(template, args...)
+}
+
+// Warnw logs a message with some additional context. The variadic key-value
+// pairs are treated as they are in With.
+func (l *lazyLogger) Warnw(msg string, keysAndValues ...interface{}) {
+	l.ZapLogger().Warnw(msg, keysAndValues...)
+}
+
+// Error uses fmt.Sprint to log a templated message.
+func (l *lazyLogger) Error(args ...interface{}) {
+	l.ZapLogger().Error(args...)
+}
+
+// Errorf uses fmt.Sprintf to log a templated message.
+func (l *lazyLogger) Errorf(template string, args ...interface{}) {
+	l.ZapLogger().Errorf(template, args...)
+}
+
+// Errorw logs a message with some additional context. The variadic key-value
+// pairs are treated as they are in With.
+func (l *lazyLogger) Errorw(msg string, keysAndValues ...interface{}) {
+	l.ZapLogger().Errorw(msg, keysAndValues...)
+}
+
+// Fatal uses fmt.Sprint to construct and log a message, then calls os.Exit.
+func (l *lazyLogger) Fatal(args ...interface{}) {
+	l.ZapLogger().Fatal(args...)
+}
+
+// Fatalf uses fmt.Sprintf to log a templated message, then calls os.Exit.
+func (l *lazyLogger) Fatalf(template string, args ...interface{}) {
+	l.ZapLogger().Fatalf(template, args...)
+}
diff --git a/pkg/log/log.go b/pkg/log/log.go
index afe149e3..72cbe9d5 100644
--- a/pkg/log/log.go
+++ b/pkg/log/log.go
@@ -4,9 +4,7 @@ import (
 	"go.uber.org/zap"
 )
 
-var Logger *zap.SugaredLogger
-
-func init() {
+var Logger = NewLazyLogger(func() (*zap.SugaredLogger, error) {
 	config := zap.Config{
 		Level:            zap.NewAtomicLevelAt(zap.InfoLevel),
 		Development:      false,
@@ -15,10 +13,13 @@ func init() {
 		OutputPaths:      []string{"stderr"},
 		ErrorOutputPaths: []string{"stderr"},
 	}
-	logger, _ := config.Build()
-	Logger = logger.Sugar()
-}
+	logger, err := config.Build()
+	if err != nil {
+		return nil, err
+	}
+	return logger.Sugar(), nil
+})
 
 func SetLogger(l *zap.SugaredLogger) {
-	Logger = l
+	Logger.zapLogger = l
 }