go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/swarming/server/rpcs/bots_get_bot.go (about)

     1  // Copyright 2023 The LUCI Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package rpcs
    16  
    17  import (
    18  	"context"
    19  
    20  	"google.golang.org/grpc/codes"
    21  	"google.golang.org/grpc/status"
    22  
    23  	"go.chromium.org/luci/common/errors"
    24  	"go.chromium.org/luci/common/logging"
    25  	"go.chromium.org/luci/gae/service/datastore"
    26  
    27  	apipb "go.chromium.org/luci/swarming/proto/api_v2"
    28  	"go.chromium.org/luci/swarming/server/acls"
    29  	"go.chromium.org/luci/swarming/server/model"
    30  )
    31  
    32  // GetBot implements the corresponding RPC method.
    33  func (*BotsServer) GetBot(ctx context.Context, req *apipb.BotRequest) (*apipb.BotInfo, error) {
    34  	if req.BotId == "" {
    35  		return nil, status.Errorf(codes.InvalidArgument, "bot_id is required")
    36  	}
    37  	res := State(ctx).ACL.CheckBotPerm(ctx, req.BotId, acls.PermPoolsListBots)
    38  	if !res.Permitted {
    39  		return nil, res.ToGrpcErr()
    40  	}
    41  
    42  	// See if the bot exists right now.
    43  	info := &model.BotInfo{Key: model.BotInfoKey(ctx, req.BotId)}
    44  	switch err := datastore.Get(ctx, info); {
    45  	case err == nil:
    46  		return info.ToProto(), nil
    47  	case !errors.Is(err, datastore.ErrNoSuchEntity):
    48  		logging.Errorf(ctx, "Error fetching BotInfo for %q: %s", req.BotId, err)
    49  		return nil, status.Errorf(codes.Internal, "datastore error fetching the bot")
    50  	}
    51  
    52  	// If there is no BotInfo, it means the bot doesn't currently exist (i.e. it
    53  	// was deleted or has never existed). Look into the event history to get its
    54  	// last known state if any. If the history is empty, it means the bot has
    55  	// never existed or had been deleted long time ago. If there's a history, it
    56  	// means the bot existed at some point, but has been deleted.
    57  	var ev *model.BotEvent
    58  	q := model.BotEventsQuery(ctx, req.BotId).Limit(1)
    59  	err := datastore.Run(ctx, q, func(ent *model.BotEvent) error {
    60  		ev = ent
    61  		return datastore.Stop
    62  	})
    63  	switch {
    64  	case err != nil:
    65  		logging.Errorf(ctx, "Error querying BotEvent for %q: %s", req.BotId, err)
    66  		return nil, status.Errorf(codes.Internal, "datastore error fetching the bot")
    67  	case ev == nil:
    68  		return nil, status.Errorf(codes.NotFound, "no such bot: %s", req.BotId)
    69  	}
    70  
    71  	// A bot may have connected right after datastore.Get(...) above, which
    72  	// created a brand new BotEvent record that the datastore.Run(...) query
    73  	// fetched. Here, another datastore.Get(...) is made to make sure the bot is
    74  	// still actually missing. If we skip this check, we may accidentally mark
    75  	// a very new bot as deleted.
    76  	//
    77  	// See https://crbug.com/1407381 for more information.
    78  	switch err := datastore.Get(ctx, info); {
    79  	case err == nil:
    80  		return info.ToProto(), nil
    81  	case !errors.Is(err, datastore.ErrNoSuchEntity):
    82  		logging.Errorf(ctx, "Error re-fetching BotInfo for %q: %s", req.BotId, err)
    83  		return nil, status.Errorf(codes.Internal, "datastore error fetching the bot")
    84  	}
    85  
    86  	// This bot existed (has a history), but is not connected anymore. Reconstruct
    87  	// its BotInfo from the last historic entry.
    88  	info.BotCommon = ev.BotCommon
    89  	info.Dimensions = ev.Dimensions
    90  	pb := info.ToProto()
    91  	pb.Deleted = true
    92  	return pb, nil
    93  }