logging: Implement rename filter, changes field key names (#4745)

modules/logging/filters.go

@@ -31,12 +31,13 @@ import (
 
 func init() {
 	caddy.RegisterModule(DeleteFilter{})
+	caddy.RegisterModule(HashFilter{})
 	caddy.RegisterModule(ReplaceFilter{})
 	caddy.RegisterModule(IPMaskFilter{})
 	caddy.RegisterModule(QueryFilter{})
 	caddy.RegisterModule(CookieFilter{})
 	caddy.RegisterModule(RegexpFilter{})
-	caddy.RegisterModule(HashFilter{})
+	caddy.RegisterModule(RenameFilter{})
 }
 
 // LogFieldFilter can filter (or manipulate)
@@ -542,21 +543,56 @@ func (f *RegexpFilter) Filter(in zapcore.Field) zapcore.Field {
 	return in
 }
 
+// RenameFilter is a Caddy log field filter that
+// renames the field's key with the indicated name.
+type RenameFilter struct {
+	Name string `json:"name,omitempty"`
+}
+
+// CaddyModule returns the Caddy module information.
+func (RenameFilter) CaddyModule() caddy.ModuleInfo {
+	return caddy.ModuleInfo{
+		ID:  "caddy.logging.encoders.filter.rename",
+		New: func() caddy.Module { return new(RenameFilter) },
+	}
+}
+
+// UnmarshalCaddyfile sets up the module from Caddyfile tokens.
+func (f *RenameFilter) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
+	for d.Next() {
+		if d.NextArg() {
+			f.Name = d.Val()
+		}
+	}
+	return nil
+}
+
+// Filter renames the input field with the replacement name.
+func (f *RenameFilter) Filter(in zapcore.Field) zapcore.Field {
+	in.Type = zapcore.StringType
+	in.Key = f.Name
+	return in
+}
+
 // Interface guards
 var (
 	_ LogFieldFilter = (*DeleteFilter)(nil)
+	_ LogFieldFilter = (*HashFilter)(nil)
 	_ LogFieldFilter = (*ReplaceFilter)(nil)
 	_ LogFieldFilter = (*IPMaskFilter)(nil)
 	_ LogFieldFilter = (*QueryFilter)(nil)
 	_ LogFieldFilter = (*CookieFilter)(nil)
 	_ LogFieldFilter = (*RegexpFilter)(nil)
+	_ LogFieldFilter = (*RenameFilter)(nil)
 
 	_ caddyfile.Unmarshaler = (*DeleteFilter)(nil)
+	_ caddyfile.Unmarshaler = (*HashFilter)(nil)
 	_ caddyfile.Unmarshaler = (*ReplaceFilter)(nil)
 	_ caddyfile.Unmarshaler = (*IPMaskFilter)(nil)
 	_ caddyfile.Unmarshaler = (*QueryFilter)(nil)
 	_ caddyfile.Unmarshaler = (*CookieFilter)(nil)
 	_ caddyfile.Unmarshaler = (*RegexpFilter)(nil)
+	_ caddyfile.Unmarshaler = (*RenameFilter)(nil)
 
 	_ caddy.Provisioner = (*IPMaskFilter)(nil)
 	_ caddy.Provisioner = (*RegexpFilter)(nil)