render context: add asset_download_token

cmd/dkl-dir2config/render-context.go

@@ -8,6 +8,7 @@ import (
 	"math/rand"
 	"path"
 	"reflect"
+	"strconv"
 	"strings"
 
 	"github.com/cespare/xxhash"
@@ -290,6 +291,14 @@ func (ctx *renderContext) templateFuncs(ctxMap map[string]any) map[string]any {
 		"host_download_token": func() (s string) {
 			return "{{ host_download_token }}"
 		},
+		"asset_download_token": func(args ...string) (s string) {
+			argsStr := new(strings.Builder)
+			for _, arg := range args {
+				argsStr.WriteByte(' ')
+				argsStr.WriteString(strconv.Quote(arg))
+			}
+			return "{{ asset_download_token" + argsStr.String() + " }}"
+		},
 
 		"hosts_of_group": func() (hosts []any) {
 			hosts = make([]any, 0)