refactor audit logging

Signed-off-by: jkoberg <jkoberg@owncloud.com>

audit/pkg/command/server.go

@@ -39,7 +39,7 @@ func Server(cfg *config.Config) *cli.Command {
 				return err
 			}
 
-			svc.StartAuditLogger(cfg.Auditlog, evts, logger)
+			svc.AuditLoggerFromConfig(cfg.Auditlog, evts, logger)
 			return nil
 		},
 	}

audit/pkg/service/service.go

@@ -11,8 +11,30 @@ import (
 	"github.com/owncloud/ocis/ocis-pkg/log"
 )
 
-// StartAuditLogger starts the audit logger
-func StartAuditLogger(c config.Auditlog, ch <-chan interface{}, log log.Logger) {
+// Log is used to log to different outputs
+type Log func([]byte)
+
+// Marshaller is used to marshal events
+type Marshaller func(interface{}) ([]byte, error)
+
+// AuditLoggerFromConfig will start a new AuditLogger generated from the config
+func AuditLoggerFromConfig(cfg config.Auditlog, ch <-chan interface{}, log log.Logger) {
+	var logs []Log
+
+	if cfg.LogToConsole {
+		logs = append(logs, WriteToStdout())
+	}
+
+	if cfg.LogToFile {
+		logs = append(logs, WriteToFile(cfg.FilePath, log))
+	}
+
+	StartAuditLogger(ch, log, Marshal(cfg.Format, log), logs...)
+
+}
+
+// StartAuditLogger will block. run in seperate go routine
+func StartAuditLogger(ch <-chan interface{}, log log.Logger, marshaller Marshaller, logto ...Log) {
 	for {
 		i := <-ch
 
@@ -26,44 +48,48 @@ func StartAuditLogger(c config.Auditlog, ch <-chan interface{}, log log.Logger)
 
 		}
 
-		b, err := marshal(auditEvent, c.Format)
+		b, err := marshaller(auditEvent)
 		if err != nil {
 			log.Error().Err(err).Msg("error marshaling the event")
 			continue
 		}
 
-		if c.LogToConsole {
-			log.Error().Msg(string(b))
+		for _, l := range logto {
+			l(b)
 		}
-
-		if c.LogToFile {
-			err := writeToFile(c.FilePath, b)
-			if err != nil {
-				log.Error().Err(err).Msg("error writing audit log file")
-			}
-		}
-
 	}
 
 }
 
-func writeToFile(path string, ev []byte) error {
-	file, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
-	if err != nil {
-		return err
+// WriteToFile returns a Log function writing to a file
+func WriteToFile(path string, log log.Logger) Log {
+	return func(content []byte) {
+		file, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
+		if err != nil {
+			log.Error().Err(err).Msgf("error opening file '%s'", path)
+			return
+		}
+		defer file.Close()
+		if _, err := fmt.Fprintln(file, string(content)); err != nil {
+			log.Error().Err(err).Msgf("error writing to file '%s'", path)
+		}
 	}
-	defer file.Close()
-	if _, err := fmt.Fprintln(file, string(ev)); err != nil {
-		return err
-	}
-	return nil
 }
 
-func marshal(ev interface{}, format string) ([]byte, error) {
+// WriteToStdout return a Log function writing to Stdout
+func WriteToStdout() Log {
+	return func(content []byte) {
+		fmt.Println(string(content))
+	}
+}
+
+// Marshal returns a Marshaller from the `format` string
+func Marshal(format string, log log.Logger) Marshaller {
 	switch format {
 	default:
-		return nil, fmt.Errorf("unsupported format '%s'", format)
+		log.Error().Msgf("unknown format '%s'", format)
+		return nil
 	case "json":
-		return json.Marshal(ev)
+		return json.Marshal
 	}
 }