tokenserver: Boilerplate for loading and serving service_accounts.cfg.

tokenserver/appengine/backend/main.go

Index: tokenserver/appengine/backend/main.go
diff --git a/tokenserver/appengine/backend/main.go b/tokenserver/appengine/backend/main.go
index 6acf865a0f1500a0552c9d4d71e0d3ebb96c8b46..55662822a5dc86d61fda3b8f24b93dba835ec384 100644
--- a/tokenserver/appengine/backend/main.go
+++ b/tokenserver/appengine/backend/main.go
@@ -66,7 +66,7 @@ func readConfigCron(c *router.Context) {
 	}
 
 	wg := sync.WaitGroup{}
-	var errs [2]error
+	var errs [3]error
 
 	wg.Add(1)
 	go func() {
@@ -86,6 +86,15 @@ func readConfigCron(c *router.Context) {
 		}
 	}()
 
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_, errs[2] = adminServer.ImportServiceAccountsConfigs(c.Context, nil)
+		if errs[2] != nil {
+			logging.Errorf(c.Context, "ImportServiceAccountsConfigs failed - %s", errs[2])
+		}
+	}()
+
 	wg.Wait()
 
 	// Retry cron job only on transient errors. On fatal errors let it rerun one