feat(logging): add built-in support for log file rotation based on ma…

…x file size in MB

helpers.logging.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"sync"
 	"time"
 
 	"go.uber.org/zap"
@@ -15,13 +16,92 @@ const (
 	LoggerContextKey ContextKey = "request.logger"
 )
 
+// RSyncWrite is a rotable and concurent safe file-based logs writer.
+// It is aimed to be used by Zap core routine. So it must implements
+// the zap.WriteSyncer interface. The rotation happens based on the
+// file size, once it reaches the max defined value.
+type RSyncWrite struct {
+	clock Clocker
+	sync.Mutex
+	file   *os.File
+	folder string
+	max    int
+	size   int64
+	isProd bool
+}
+
+func NewRSyncWriter(config *Config, clock Clocker) *RSyncWrite {
+	return &RSyncWrite{
+		clock:  clock,
+		folder: config.LogFolder,
+		max:    config.LogMaxSize,
+		isProd: config.IsProduction,
+	}
+}
+
+// Close closes the current log file.
+func (rsw *RSyncWrite) Close() error {
+	rsw.Lock()
+	defer rsw.Unlock()
+	if rsw.file == nil {
+		return nil
+	}
+	return rsw.file.Close()
+}
+
+func (rsw *RSyncWrite) Sync() error {
+	return rsw.file.Sync()
+}
+
+// Write implements the io.Writer interface with dynamic file rotation capability on max size.
+func (rsw *RSyncWrite) Write(p []byte) (n int, err error) {
+	rsw.Lock()
+	defer rsw.Unlock()
+	pLen := len(p)
+	if pLen > rsw.max*1048576 {
+		return 0, fmt.Errorf("logging: log size %d exceeds max file size %d", pLen, rsw.max)
+	}
+	if int64(pLen)+rsw.size > int64(rsw.max)*1048576 || rsw.file == nil {
+		if rsw.file != nil {
+			if err := rsw.file.Close(); err != nil {
+				return 0, err
+			}
+		}
+
+		path := CreateLogFilePath(rsw.folder, rsw.isProd, rsw.clock.Now())
+		file, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
+		if err != nil {
+			return 0, err
+		}
+		rsw.file = file
+		rsw.size = 0
+	}
+	n, err = rsw.file.Write(p)
+	rsw.size += int64(pLen)
+	return n, err
+}
+
+// SyncWrite implements zap.SyncWriter. This is a small hack to avoid usual
+// `Handle is invalid` error when calling Sync() on logger using os.stdout.
+type SyncWrite struct {
+	out *os.File
+}
+
+func (sw *SyncWrite) Sync() error {
+	return nil
+}
+
+func (sw *SyncWrite) Write(p []byte) (n int, err error) {
+	return sw.out.Write(p)
+}
+
 // SetupLogging is a helper function that initializes the logging module.
 // In production all logs are saved to the defined file. In development
 // the same logs are printed to standard output as well. It only adds
 // stacktrace to fatal level logs. All logs come with commit & tag value.
 // The custom clock provides timestamp in UTC for production environment
 // and timestamp in Local timezone in development setup.
-func SetupLogging(config *Config, logFile *os.File, clock TickerClocker) (*zap.Logger, func() error) {
+func SetupLogging(config *Config, w *RSyncWrite, clock TickerClocker) (*zap.Logger, func() error) {
 	var logger *zap.Logger
 	if config.IsProduction {
 		zapConfig := zap.NewProductionEncoderConfig()
@@ -33,7 +113,7 @@ func SetupLogging(config *Config, logFile *os.File, clock TickerClocker) (*zap.L
 		zapConfig.CallerKey = "caller"
 		zapConfig.StacktraceKey = "skt"
 		fileEncoder := zapcore.NewJSONEncoder(zapConfig)
-		zapCore := zapcore.NewTee(zapcore.NewCore(fileEncoder, zapcore.AddSync(logFile), config.LogLevel))
+		zapCore := zapcore.NewTee(zapcore.NewCore(fileEncoder, w, config.LogLevel))
 		logger = zap.New(zapCore, zap.AddCaller(), zap.AddStacktrace(zapcore.FatalLevel))
 		logger = logger.WithOptions(zap.WithClock(clock))
 	} else {
@@ -48,8 +128,8 @@ func SetupLogging(config *Config, logFile *os.File, clock TickerClocker) (*zap.L
 		fileEncoder := zapcore.NewJSONEncoder(zapConfig)
 		consoleEncoder := zapcore.NewConsoleEncoder(zapConfig)
 		zapCore := zapcore.NewTee(
-			zapcore.NewCore(fileEncoder, zapcore.AddSync(logFile), config.LogLevel),
-			zapcore.NewCore(consoleEncoder, zapcore.AddSync(os.Stdout), config.LogLevel))
+			zapcore.NewCore(fileEncoder, w, config.LogLevel),
+			zapcore.NewCore(consoleEncoder, zapcore.Lock(&SyncWrite{os.Stdout}), config.LogLevel))
 		logger = zap.New(zapCore, zap.AddCaller(), zap.AddStacktrace(zapcore.FatalLevel))
 		logger = logger.WithOptions(zap.WithClock(clock))
 	}