Delay salt initialization for audit backends

audit/format_jsonx.go

@@ -5,13 +5,15 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/hashicorp/vault/helper/salt"
 	"github.com/jefferai/jsonx"
 )
 
 // JSONxFormatWriter is an AuditFormatWriter implementation that structures data into
 // a XML format.
 type JSONxFormatWriter struct {
-	Prefix string
+	Prefix   string
+	SaltFunc func() (*salt.Salt, error)
 }
 
 func (f *JSONxFormatWriter) WriteRequest(w io.Writer, req *AuditRequestEntry) error {
@@ -65,3 +67,7 @@ func (f *JSONxFormatWriter) WriteResponse(w io.Writer, resp *AuditResponseEntry)
 	_, err = w.Write(xmlBytes)
 	return err
 }
+
+func (f *JSONxFormatWriter) Salt() (*salt.Salt, error) {
+	return f.SaltFunc()
+}