[errors] Greatly simplify common/errors package.

dm/appengine/deps/auth.go

 // Copyright 2016 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package deps
 
 import (
         "github.com/luci/luci-go/common/errors"
         "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/retry/transient"
         "github.com/luci/luci-go/dm/api/acls"
         "github.com/luci/luci-go/grpc/grpcutil"
         "github.com/luci/luci-go/luci_config/server/cfgclient"
         "github.com/luci/luci-go/luci_config/server/cfgclient/textproto"
         "github.com/luci/luci-go/server/auth"
 
         "golang.org/x/net/context"
         "google.golang.org/grpc/codes"
 )
 
 func loadAcls(c context.Context) (ret *acls.Acls, err error) {
         cSet := cfgclient.CurrentServiceConfigSet(c)
         file := "acls.cfg"
 
         ret = &acls.Acls{}
         if err := cfgclient.Get(c, cfgclient.AsService, cSet, file, textproto.Message(ret), nil); err != nil {
-                return nil, errors.Annotate(err).Tag(transient.Tag).
-                        D("cSet", cSet).D("file", file).InternalReason("loading config").Err()
+                return nil, errors.Annotate(err, "").Tag(transient.Tag).
+                        InternalReason("loading config :: cSet(%v)/file(%v)", cSet, file).Err()
         }
         return
 }
 
 func inGroups(c context.Context, groups []string) error {
         for _, grp := range groups {
                 ok, err := auth.IsMember(c, grp)
                 if err != nil {
-                        return grpcAnnotate(err, codes.Internal).Reason("failed group check").Err()
+                        return grpcAnnotate(err, codes.Internal, "failed group check").Err()
                 }
                 if ok {
                         return nil
                 }
         }
         logging.Fields{
                 "ident":  auth.CurrentIdentity(c),
                 "groups": groups,
         }.Infof(c, "not authorized")
         return grpcutil.Errf(codes.PermissionDenied, "not authorized")
@@ skipping 10 matching lines @@
         return
 }
 
 func canWrite(c context.Context) (err error) {
         acl, err := loadAcls(c)
         if err != nil {
                 return
         }
         return inGroups(c, acl.Writers)
 }