Use io.Discard instead of /dev/null for discarding output

loggers/concurrent_writer.go

@@ -29,15 +29,19 @@ type concurrentWriter struct {
 }
 
 func (cl *concurrentWriter) Init(c types.Config) error {
-	fileName := c.Get("auditlog_file", "/dev/null").(string)
 	cl.auditFileMode = c.Get("auditlog_file_mode", fs.FileMode(0644)).(fs.FileMode)
 	cl.auditDir = c.Get("auditlog_dir", "").(string)
 	cl.auditDirMode = c.Get("auditlog_dir_mode", fs.FileMode(0755)).(fs.FileMode)
 	cl.formatter = c.Get("auditlog_formatter", nativeFormatter).(LogFormatter)
 	cl.mux = &sync.RWMutex{}
-	faudit, err := os.OpenFile(fileName, os.O_CREATE|os.O_WRONLY|os.O_APPEND, cl.auditFileMode)
-	if err != nil {
-		return err
+
+	faudit := io.Discard
+	if fileName := c.Get("auditlog_file", "").(string); fileName != "" {
+		f, err := os.OpenFile(fileName, os.O_CREATE|os.O_WRONLY|os.O_APPEND, cl.auditFileMode)
+		if err != nil {
+			return err
+		}
+		faudit = f
 	}
 	mw := io.MultiWriter(faudit)
 	cl.auditlogger = log.New(mw, "", 0)

loggers/serial_writer.go

@@ -7,6 +7,7 @@
 package loggers
 
 import (
+	"io"
 	"io/fs"
 	"log"
 	"os"
@@ -16,22 +17,31 @@ import (
 
 // serialWriter is used to store logs in a single file
 type serialWriter struct {
-	file      *os.File
+	file      io.Closer
 	log       log.Logger
 	formatter LogFormatter
 }
 
 func (sl *serialWriter) Init(c types.Config) error {
-	fileName := c.Get("auditlog_file", "/dev/null").(string)
 	fileMode := c.Get("auditlog_file_mode", fs.FileMode(0644)).(fs.FileMode)
 	sl.formatter = c.Get("auditlog_formatter", nativeFormatter).(LogFormatter)
-	var err error
-	sl.file, err = os.OpenFile(fileName, os.O_APPEND|os.O_CREATE|os.O_WRONLY, fileMode)
-	if err != nil {
-		return err
+
+	fileName := c.Get("auditlog_file", "").(string)
+	var file io.Writer
+	if fileName != "" {
+		f, err := os.OpenFile(fileName, os.O_APPEND|os.O_CREATE|os.O_WRONLY, fileMode)
+		if err != nil {
+			return err
+		}
+		file = f
+		sl.file = f
+	} else {
+		file = io.Discard
+		// Nothing to close so just set a no-op
+		sl.file = noopCloser{}
 	}
 	sl.log.SetFlags(0)
-	sl.log.SetOutput(sl.file)
+	sl.log.SetOutput(file)
 	return nil
 }
 
@@ -50,3 +60,11 @@ func (sl *serialWriter) Close() error {
 }
 
 var _ LogWriter = (*serialWriter)(nil)
+
+type noopCloser struct{}
+
+var _ io.Closer = (*noopCloser)(nil)
+
+func (nc noopCloser) Close() error {
+	return nil
+}

waf.go

@@ -6,6 +6,7 @@ package coraza
 import (
 	"context"
 	"fmt"
+	"io"
 	"io/fs"
 	"log"
 	"os"
@@ -416,6 +417,7 @@ func (w *Waf) NewTransaction(ctx context.Context) *Transaction {
 // note: this is not thread safe
 func (w *Waf) SetDebugLogPath(path string) error {
 	if path == "" {
+		w.Logger.SetOutput(io.Discard)
 		return nil
 	}
 	f, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
@@ -453,11 +455,11 @@ func NewWaf() *Waf {
 		RequestBodyAccess:        false,
 		Logger:                   logger,
 	}
-	// We initialize a basic audit log writer to /dev/null
+	// We initialize a basic audit log writer that discards output
 	if err := logWriter.Init(types.Config{}); err != nil {
 		fmt.Println(err)
 	}
-	if err := waf.SetDebugLogPath("/dev/null"); err != nil {
+	if err := waf.SetDebugLogPath(""); err != nil {
 		fmt.Println(err)
 	}
 	waf.Logger.Debug("a new waf instance was created")