admin: Preserve "@id" fields through partial changes (fixes #2902)

1 files changed, 7 insertions, 0 deletions

diff --git a/admin.go b/admin.go
index b1ced18e7..981f2dc17 100644
--- a/admin.go
+++ b/admin.go
@@ -27,6 +27,7 @@ import (
 	"net/url"
 	"os"
 	"path"
+	"regexp"
 	"strconv"
 	"strings"
 	"sync"
@@ -764,6 +765,12 @@ var (
 	}
 )
 
+// idRegexp is used to match ID fields and their associated values
+// in the config. It also matches adjacent commas so that syntax
+// can be preserved no matter where in the object the field appears.
+// It supports string and most numeric values.
+var idRegexp = regexp.MustCompile(`(?m),?\s*"` + idKey + `":\s?(-?[0-9]+(\.[0-9]+)?|(?U)".*")\s*,?`)
+
 const (
 	rawConfigKey = "config"
 	idKey        = "@id"