Add logfile feature

docs/Webhook-Parameters.md

@@ -19,6 +19,8 @@ Usage of webhook:
         path to the HTTPS certificate private key pem file (default "key.pem")
   -list-cipher-suites
         list available TLS cipher suites
+  -logfile string
+        send log output to a file; implicitly enables verbose logging
   -nopanic
         do not panic if hooks cannot be loaded when webhook is not running in verbose mode
   -port int

webhook.go

@@ -33,6 +33,7 @@ var (
 	ip                 = flag.String("ip", "0.0.0.0", "ip the webhook should serve hooks on")
 	port               = flag.Int("port", 9000, "port the webhook should serve hooks on")
 	verbose            = flag.Bool("verbose", false, "show verbose output")
+	logPath            = flag.String("logfile", "", "send log output to a file; implicitly enables verbose logging")
 	debug              = flag.Bool("debug", false, "show debug output")
 	noPanic            = flag.Bool("nopanic", false, "do not panic if hooks cannot be loaded when webhook is not running in verbose mode")
 	hotReload          = flag.Bool("hotreload", false, "watch hooks file for changes and reload them automatically")
@@ -103,7 +104,7 @@ func main() {
 		os.Exit(1)
 	}
 
-	if *debug {
+	if *debug || *logPath != "" {
 		*verbose = true
 	}
 
@@ -111,6 +112,17 @@ func main() {
 		hooksFiles = append(hooksFiles, "hooks.json")
 	}
 
+	if *logPath != "" {
+		file, err := os.OpenFile(*logPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
+		if err != nil {
+			log.Printf("error opening log file %q: %v", *logPath, err)
+
+			return
+		}
+
+		log.SetOutput(file)
+	}
+
 	log.SetPrefix("[webhook] ")
 	log.SetFlags(log.Ldate | log.Ltime)