✨ feat(logs) add supports write logs to files (#217)

* ✨ feat(logs) add supports write logs to files

* fix(lint) 🚨 fix go lint

* 🐛 fix(bug) check path is done only if provided

* 📝 doc(vars) add LogFilePath to vars

* 🦺 chore(review) update doc, configuration check and logger

pkg/logger/logger.go

@@ -3,9 +3,11 @@
 package logger
 
 import (
+	"fmt"
 	"io"
 	"log"
 	"os"
+	"path/filepath"
 )
 
 // Log Logger struct.
@@ -16,15 +18,30 @@ type Log struct {
 }
 
 // New Set Default log level to info in case log level to defined.
-func New(logLevel string) *Log {
+func New(logLevel string, logFilePath string) *Log {
 	logError := log.New(io.Discard, "ERROR: CrowdsecBouncerTraefikPlugin: ", log.Ldate|log.Ltime)
 	logInfo := log.New(io.Discard, "INFO: CrowdsecBouncerTraefikPlugin: ", log.Ldate|log.Ltime)
 	logDebug := log.New(io.Discard, "DEBUG: CrowdsecBouncerTraefikPlugin: ", log.Ldate|log.Ltime)
+
 	logError.SetOutput(os.Stderr)
 	logInfo.SetOutput(os.Stdout)
+	// we initialize logger to STDOUT/STDERR first so if the file logger cannot be initialized we can inform the user
 	if logLevel == "DEBUG" {
 		logDebug.SetOutput(os.Stdout)
 	}
+	if logFilePath != "" {
+		logFile, err := os.OpenFile(filepath.Clean(logFilePath), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0600)
+		if err != nil {
+			_ = fmt.Errorf("LogFilePath is not writable %w", err)
+		} else {
+			logInfo.SetOutput(logFile)
+			logError.SetOutput(logFile)
+			if logLevel == "DEBUG" {
+				logDebug.SetOutput(logFile)
+			}
+		}
+	}
+
 	return &Log{
 		logError: logError,
 		logInfo:  logInfo,