Fix audit log file permission and use date suffix in name (#181)

Signed-off-by: Congqi Xia <[email protected]>

states/instance.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path"
+	"time"
 
 	"github.com/milvus-io/birdwatcher/configs"
 	"github.com/milvus-io/birdwatcher/framework"
@@ -119,7 +120,8 @@ func (s *InstanceState) DryModeCommand(ctx context.Context, p *DryModeParam) {
 
 func getInstanceState(parent *framework.CmdState, cli clientv3.KV, instanceName, metaPath string, etcdState framework.State, config *configs.Config) framework.State {
 	var kv clientv3.KV
-	file, err := os.OpenFile("audit.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, os.ModeAppend)
+	name := fmt.Sprintf("audit_%s.log", time.Now().Format("2006_0102_150405"))
+	file, err := os.OpenFile(name, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
 		fmt.Println("failed to open audit.log file!")
 		kv = cli