Milo: Handle missing / transient LogDog failures.

milo/appengine/logdog/build.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 logdog
 
 import (
         "fmt"
         "net/http"
         "time"
 
         log "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/proto/google"
         miloProto "github.com/luci/luci-go/common/proto/milo"
-        "github.com/luci/luci-go/grpc/grpcutil"
         "github.com/luci/luci-go/logdog/api/logpb"
         "github.com/luci/luci-go/logdog/client/coordinator"
         "github.com/luci/luci-go/logdog/common/types"
         "github.com/luci/luci-go/logdog/common/viewer"
         "github.com/luci/luci-go/luci_config/common/cfgtypes"
         "github.com/luci/luci-go/milo/api/resp"
         "github.com/luci/luci-go/milo/appengine/logdog/internal"
         "github.com/luci/luci-go/milo/common/miloerror"
 
         "github.com/golang/protobuf/proto"
         mc "github.com/luci/gae/service/memcache"
         "golang.org/x/net/context"
-        "google.golang.org/grpc/codes"
 )
 
 const (
         // intermediateCacheLifetime is the amount of time to cache intermediate (non-
         // terminal) annotation streams. Terminal annotation streams are cached
         // indefinitely.
         intermediateCacheLifetime = 10 * time.Second
 
         // defaultLogDogHost is the default LogDog host, if one isn't specified via
         // query string.
@@ skipping 72 matching lines @@
         log.Fields{
                 "host":    as.Client.Host,
                 "project": as.Project,
                 "path":    as.Path,
         }.Infof(c, "Making tail request to LogDog to fetch annotation stream.")
 
         var (
                 state  coordinator.LogStream
                 stream = as.Client.Stream(as.Project, as.Path)
         )
+
         le, err := stream.Tail(c, coordinator.WithState(&state), coordinator.Complete())
-        switch code := grpcutil.Code(err); code {
-        case codes.OK:
-                break
-
-        case codes.NotFound:
-                return nil, &miloerror.Error{
-                        Message: "Stream not found",
-                        Code:    http.StatusNotFound,
-                }
-
-        default:
-                // TODO: Once we switch to delegation tokens and are making the request on
-                // behalf of a user rather than the Milo service, handle PermissionDenied.
-                log.Fields{
-                        log.ErrorKey: err,
-                        "code":       code,
-                }.Errorf(c, "Failed to load LogDog annotation stream.")
-                return nil, &miloerror.Error{
-                        Message: "Failed to load stream",
-                        Code:    http.StatusInternalServerError,
-                }
+        if err != nil {
+                log.WithError(err).Errorf(c, "Failed to load stream.")
+                return nil, err
         }
 
         // Make sure that this is an annotation stream.
         switch {
         case state.Desc.ContentType != miloProto.ContentTypeAnnotations:
                 return nil, &miloerror.Error{
                         Message: "Requested stream is not a Milo annotation protobuf",
                         Code:    http.StatusBadRequest,
                 }
 
@@ skipping 152 matching lines @@
                 if link.Label == "" {
                         link.Label = "unnamed"
                 }
                 return &link
 
         default:
                 // Don't know how to render.
                 return nil
         }
 }