[errors] de-specialize Transient in favor of Tags.

server/auth/delegation.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 auth
 
 import (
         "fmt"
         "net/http"
         "strings"
         "time"
 
         "golang.org/x/net/context"
 
         "github.com/luci/luci-go/common/clock"
-        "github.com/luci/luci-go/common/errors"
         "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/retry"
+        "github.com/luci/luci-go/common/retry/transient"
         "github.com/luci/luci-go/grpc/grpcutil"
         "github.com/luci/luci-go/grpc/prpc"
         "github.com/luci/luci-go/server/auth/delegation"
         "github.com/luci/luci-go/server/auth/delegation/messages"
         "github.com/luci/luci-go/server/auth/identity"
         "github.com/luci/luci-go/tokenserver/api/minter/v1"
 )
 
 var (
-        // ErrTokenServerNotConfigured is returned by MintDelegationToken if the
+        // ErrTokenServiceNotConfigured is returned by MintDelegationToken if the
         // token service URL is not configured. This usually means the corresponding
         // auth service is not paired with a token server.
         ErrTokenServiceNotConfigured = fmt.Errorf("auth: token service URL is not configured")
 
         // ErrBrokenTokenService is returned by MintDelegationToken if the RPC to the
         // token service succeeded, but response doesn't make sense. This should not
         // generally happen.
         ErrBrokenTokenService = fmt.Errorf("auth: unrecognized response from the token service")
 
         // ErrAnonymousDelegation is returned by MintDelegationToken if it is used in
@@ skipping 189 matching lines @@
                         // The actual RPC call.
                         resp, err := rpcClient.MintDelegationToken(ctx, &minter.MintDelegationTokenRequest{
                                 DelegatedIdentity: string(userID),
                                 ValidityDuration:  int64(MaxDelegationTokenTTL.Seconds()),
                                 Audience:          []string{"REQUESTOR"}, // make the token usable only by the calling service
                                 Services:          []string{target},
                                 Intent:            p.Intent,
                         })
                         if err != nil {
                                 err = grpcutil.WrapIfTransient(err)
-                                if errors.IsTransient(err) {
+                                if transient.Tag.In(err) {
                                         return nil, err, "ERROR_TRANSIENT_IN_MINTING"
                                 }
                                 return nil, err, "ERROR_MINTING"
                         }
 
                         // Sanity checks. A correctly working token server should not trigger them.
                         subtoken := resp.DelegationSubtoken
                         good := false
                         switch {
                         case subtoken == nil:
@@ skipping 31 matching lines @@
 
         if err != nil {
                 report(err, label)
                 return nil, err
         }
 
         t := cached.Token.(delegation.Token) // let it panic on type mismatch
         report(nil, label)
         return &t, nil
 }