tokenserver: Boilerplate for loading and serving service_accounts.cfg.

tokenserver/appengine/backend/main.go

 // Copyright 2017 The LUCI Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 48 matching lines @@
 
 // readConfigCron is handler for /internal/cron/read-config GAE cron task.
 func readConfigCron(c *router.Context) {
         // Don't override manually imported configs with 'nil' on devserver.
         if info.IsDevAppServer(c.Context) {
                 c.Writer.WriteHeader(http.StatusOK)
                 return
         }
 
         wg := sync.WaitGroup{}
-        var errs [2]error
+        var errs [3]error
 
         wg.Add(1)
         go func() {
                 defer wg.Done()
                 _, errs[0] = adminServer.ImportCAConfigs(c.Context, nil)
                 if errs[0] != nil {
                         logging.Errorf(c.Context, "ImportCAConfigs failed - %s", errs[0])
                 }
         }()
 
         wg.Add(1)
         go func() {
                 defer wg.Done()
                 _, errs[1] = adminServer.ImportDelegationConfigs(c.Context, nil)
                 if errs[1] != nil {
                         logging.Errorf(c.Context, "ImportDelegationConfigs failed - %s", errs[1])
                 }
         }()
 
+        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
         // minute later, as usual, to avoid spamming logs with errors.
         c.Writer.WriteHeader(statusFromErrs(errs[:]))
 }
 
 // fetchCRLCron is handler for /internal/cron/fetch-crl GAE cron task.
 func fetchCRLCron(c *router.Context) {
         list, err := caServer.ListCAs(c.Context, nil)
@@ skipping 41 matching lines @@
 
 // statusFromErrs returns 500 if any of gRPC errors is codes.Internal.
 func statusFromErrs(errs []error) int {
         for _, err := range errs {
                 if grpc.Code(err) == codes.Internal {
                         return http.StatusInternalServerError
                 }
         }
         return http.StatusOK
 }