more clearly error info

conf/conf.go

@@ -2,6 +2,7 @@ package conf
 
 import (
 	"errors"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path"
@@ -178,12 +179,12 @@ func (c *Conf) genUUID() (string, error) {
 
 	uuidDir := path.Dir(c.UUIDFile)
 	if err := os.MkdirAll(uuidDir, 0755); err != nil {
-		return "", err
+		return "", fmt.Errorf("failed to write UUID to file: %s. you can change UUIDFile config in base.json", err)
 	}
 
 	err = ioutil.WriteFile(c.UUIDFile, []byte(u.String()), 0600)
 	if err != nil {
-		return "", err
+		return "", fmt.Errorf("failed to write UUID to file: %s. you can change UUIDFile config in base.json", err)
 	}
 
 	return u.String(), nil

node/node.go

@@ -121,14 +121,14 @@ func (n *Node) writePIDFile() {
 	dir := path.Dir(n.PIDFile)
 	err := os.MkdirAll(dir, 0755)
 	if err != nil {
-		log.Errorf("Failed to write pid file: %s", err)
+		log.Errorf("Failed to write pid file: %s. you can change PIDFile config in base.json", err)
 		return
 	}
 
 	n.PIDFile = path.Join(dir, filename)
 	err = ioutil.WriteFile(n.PIDFile, []byte(n.PID), 0644)
 	if err != nil {
-		log.Errorf("Failed to write pid file: %s", err)
+		log.Errorf("Failed to write pid file: %s. you can change PIDFile config in base.json", err)
 		return
 	}
 }