enabled file logging with log rotation

server/logging/file_logger.go

@@ -0,0 +1,80 @@
+package logging
+
+import (
+	"compress/gzip"
+	"io"
+	"os"
+	"sync"
+	"time"
+)
+
+// implements io.Writer interface
+type LogRotateWriter struct {
+	mu       sync.Mutex
+	fd       *os.File
+	filename string
+}
+
+func NewRotableLogger(filename string) (*LogRotateWriter, error) {
+	fd, err := os.Create(filename)
+	if err != nil {
+		return nil, err
+	}
+	w := &LogRotateWriter{filename: filename, fd: fd}
+	return w, nil
+}
+
+func (w *LogRotateWriter) Write(b []byte) (int, error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	return w.fd.Write(b)
+}
+
+func (w *LogRotateWriter) Rotate() error {
+	var err error
+	w.mu.Lock()
+
+	gzFile, err := os.Create(w.filename + "." + time.Now().Format(time.RFC3339) + ".gz")
+	if err != nil {
+		return err
+	}
+
+	data, err := io.ReadAll(w.fd)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		w.mu.Unlock()
+		w.gzipLog(gzFile, &data)
+	}()
+
+	_, err = os.Stat(w.filename)
+	if err != nil {
+		return err
+	}
+
+	if w.fd != nil {
+		err = w.fd.Close()
+		w.fd = nil
+		if err != nil {
+			return err
+		}
+	}
+
+	err = os.Remove(w.filename)
+	if err != nil {
+		return err
+	}
+
+	w.fd, err = os.Create(w.filename)
+	return err
+}
+
+func (w *LogRotateWriter) gzipLog(wr io.Writer, data *[]byte) error {
+	if _, err := gzip.NewWriter(wr).Write(*data); err != nil {
+		return err
+	}
+
+	return nil
+}