BSONObj ShardingCatalogManagerImpl::createShardIdentityUpsertForAddShard(
OperationContext* opCtx, const std::string& shardName) {
std::unique_ptr<BatchedUpdateDocument> updateDoc(new BatchedUpdateDocument());
BSONObjBuilder query;
query.append("_id", "shardIdentity");
query.append(ShardIdentityType::shardName(), shardName);
query.append(ShardIdentityType::clusterId(), ClusterIdentityLoader::get(opCtx)->getClusterId());
updateDoc->setQuery(query.obj());
BSONObjBuilder update;
{
BSONObjBuilder set(update.subobjStart("$set"));
set.append(
ShardIdentityType::configsvrConnString(),
repl::ReplicationCoordinator::get(opCtx)->getConfig().getConnectionString().toString());
}
updateDoc->setUpdateExpr(update.obj());
updateDoc->setUpsert(true);
std::unique_ptr<BatchedUpdateRequest> updateRequest(new BatchedUpdateRequest());
updateRequest->addToUpdates(updateDoc.release());
BatchedCommandRequest commandRequest(updateRequest.release());
commandRequest.setNS(NamespaceString::kConfigCollectionNamespace);
commandRequest.setWriteConcern(ShardingCatalogClient::kMajorityWriteConcern.toBSON());
return commandRequest.toBSON();
}
StatusWith<string> ShardingCatalogManagerImpl::addShard(
OperationContext* txn,
const std::string* shardProposedName,
const ConnectionString& shardConnectionString,
const long long maxSize) {
if (shardConnectionString.type() == ConnectionString::INVALID) {
return {ErrorCodes::BadValue, "Invalid connection string"};
}
if (shardProposedName && shardProposedName->empty()) {
return {ErrorCodes::BadValue, "shard name cannot be empty"};
}
// TODO: Don't create a detached Shard object, create a detached RemoteCommandTargeter instead.
const std::shared_ptr<Shard> shard{
Grid::get(txn)->shardRegistry()->createConnection(shardConnectionString)};
invariant(shard);
auto targeter = shard->getTargeter();
// Validate the specified connection string may serve as shard at all
auto shardStatus =
_validateHostAsShard(txn, targeter, shardProposedName, shardConnectionString);
if (!shardStatus.isOK()) {
// TODO: This is a workaround for the case were we could have some bad shard being
// requested to be added and we put that bad connection string on the global replica set
// monitor registry. It needs to be cleaned up so that when a correct replica set is added,
// it will be recreated.
ReplicaSetMonitor::remove(shardConnectionString.getSetName());
return shardStatus.getStatus();
}
ShardType& shardType = shardStatus.getValue();
auto dbNamesStatus = _getDBNamesListFromShard(txn, targeter);
if (!dbNamesStatus.isOK()) {
return dbNamesStatus.getStatus();
}
// Check that none of the existing shard candidate's dbs exist already
for (const string& dbName : dbNamesStatus.getValue()) {
auto dbt = _catalogClient->getDatabase(txn, dbName);
if (dbt.isOK()) {
const auto& dbDoc = dbt.getValue().value;
return Status(ErrorCodes::OperationFailed,
str::stream() << "can't add shard "
<< "'"
<< shardConnectionString.toString()
<< "'"
<< " because a local database '"
<< dbName
<< "' exists in another "
<< dbDoc.getPrimary());
} else if (dbt != ErrorCodes::NamespaceNotFound) {
return dbt.getStatus();
}
}
// If a name for a shard wasn't provided, generate one
if (shardType.getName().empty()) {
StatusWith<string> result = _generateNewShardName(txn);
if (!result.isOK()) {
return result.getStatus();
}
shardType.setName(result.getValue());
}
if (maxSize > 0) {
shardType.setMaxSizeMB(maxSize);
}
ShardIdentityType shardIdentity;
shardIdentity.setConfigsvrConnString(
Grid::get(txn)->shardRegistry()->getConfigServerConnectionString());
shardIdentity.setShardName(shardType.getName());
shardIdentity.setClusterId(Grid::get(txn)->shardRegistry()->getClusterId());
auto validateStatus = shardIdentity.validate();
if (!validateStatus.isOK()) {
return validateStatus;
}
log() << "going to insert shardIdentity document into shard: " << shardIdentity.toString();
auto updateRequest = shardIdentity.createUpsertForAddShard();
BatchedCommandRequest commandRequest(updateRequest.release());
commandRequest.setNS(NamespaceString::kConfigCollectionNamespace);
commandRequest.setWriteConcern(kMajorityWriteConcern.toBSON());
auto swCommandResponse =
_runCommandForAddShard(txn, targeter.get(), "admin", commandRequest.toBSON());
if (!swCommandResponse.isOK()) {
return swCommandResponse.getStatus();
}
auto commandResponse = std::move(swCommandResponse.getValue());
BatchedCommandResponse batchResponse;
auto batchResponseStatus =
Shard::CommandResponse::processBatchWriteResponse(commandResponse, &batchResponse);
if (!batchResponseStatus.isOK()) {
return batchResponseStatus;
}
log() << "going to insert new entry for shard into config.shards: " << shardType.toString();
Status result =
_catalogClient->insertConfigDocument(txn, ShardType::ConfigNS, shardType.toBSON());
if (!result.isOK()) {
log() << "error adding shard: " << shardType.toBSON() << " err: " << result.reason();
if (result == ErrorCodes::DuplicateKey) {
// TODO(SERVER-24213): adding a shard that already exists should be considered success,
// however this approach does no validation that we are adding the shard with the same
// options. It also does not protect against adding the same shard with a different
// shard name and slightly different connection string. This is a temporary hack to
// get the continuous stepdown suite passing.
warning() << "Received duplicate key error when inserting new shard with name "
<< shardType.getName() << " and connection string "
<< shardConnectionString.toString()
<< " to config.shards collection. This most likely means that there was an "
"attempt to add a shard that already exists in the cluster";
return shardType.getName();
}
return result;
}
// Add all databases which were discovered on the new shard
for (const string& dbName : dbNamesStatus.getValue()) {
DatabaseType dbt;
dbt.setName(dbName);
dbt.setPrimary(shardType.getName());
dbt.setSharded(false);
Status status = _catalogClient->updateDatabase(txn, dbName, dbt);
if (!status.isOK()) {
log() << "adding shard " << shardConnectionString.toString()
<< " even though could not add database " << dbName;
}
}
// Record in changelog
BSONObjBuilder shardDetails;
shardDetails.append("name", shardType.getName());
shardDetails.append("host", shardConnectionString.toString());
_catalogClient->logChange(txn, "addShard", "", shardDetails.obj());
// Ensure the added shard is visible to this process.
auto shardRegistry = Grid::get(txn)->shardRegistry();
if (!shardRegistry->getShard(txn, shardType.getName())) {
return {ErrorCodes::OperationFailed,
"Could not find shard metadata for shard after adding it. This most likely "
"indicates that the shard was removed immediately after it was added."};
}
return shardType.getName();
}