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/**
* Copyright (C) 2021-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/db/process_health/dns_health_observer.h"
#include "mongo/db/process_health/health_observer_registration.h"
#include "mongo/logv2/log.h"
#include "mongo/s/grid.h"
#include "mongo/util/dns_name.h"
#include "mongo/util/net/hostandport.h"
#include "mongo/util/net/hostname_canonicalization.h"
#include <algorithm>
#include <random>
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kProcessHealth
namespace mongo {
namespace process_health {
MONGO_FAIL_POINT_DEFINE(dnsHealthObserverFp);
Future<HealthCheckStatus> DnsHealthObserver::periodicCheckImpl(
PeriodicHealthCheckContext&& periodicCheckContext) noexcept {
LOGV2_DEBUG(5938401, 2, "DNS health observer executing");
auto makeFailedHealthCheckFuture = [this](const Status& status) {
return Future<HealthCheckStatus>::makeReady(
makeSimpleFailedStatus(Severity::kFailure, {status}));
};
ConnectionString connString;
auto isFailPointActive = false;
if (MONGO_unlikely(dnsHealthObserverFp.shouldFail())) {
isFailPointActive = true;
dnsHealthObserverFp.executeIf(
[this, &connString](const BSONObj& data) {
auto fpHostname = data["hostname"].String();
connString = ConnectionString::forReplicaSet("serverWithBadHostName",
{HostAndPort(fpHostname, 27017)});
},
[&](const BSONObj& data) { return !data.isEmpty(); });
}
if (!isFailPointActive) {
auto client = _svcCtx->makeClient("DNSHealthObserver");
auto opCtx = client->makeOperationContext();
auto const shardRegistry = Grid::get(_svcCtx)->shardRegistry();
auto shardIds = shardRegistry->getAllShardIds(opCtx.get());
if (shardIds.size() == 0) {
connString = shardRegistry->getConfigServerConnectionString();
} else {
auto shardSW =
shardRegistry->getShard(opCtx.get(), shardIds.at(rand() % shardIds.size()));
auto shardSWStatus = shardSW.getStatus();
if (shardSWStatus.isOK()) {
connString = shardSW.getValue()->getConnString();
} else {
return makeFailedHealthCheckFuture(shardSWStatus);
}
}
}
auto servers = connString.getServers();
if (servers.empty()) {
return makeFailedHealthCheckFuture(
Status(ErrorCodes::NetworkTimeout, "No hostnames for DNS health check"));
}
std::shuffle(servers.begin(), servers.end(), _random.urbg());
auto completionPf = makePromiseFuture<HealthCheckStatus>();
auto status = periodicCheckContext.taskExecutor->scheduleWork(
[this, servers, promise = std::move(completionPf.promise)](
const executor::TaskExecutor::CallbackArgs& cbArgs) mutable {
auto statusWith =
getHostFQDNs(servers.front().host(), HostnameCanonicalizationMode::kForward);
if (statusWith.isOK() && !statusWith.getValue().empty()) {
promise.emplaceValue(makeHealthyStatus());
} else {
promise.emplaceValue(
makeSimpleFailedStatus(Severity::kFailure, {statusWith.getStatus()}));
}
});
return std::move(completionPf.future);
}
namespace {
MONGO_INITIALIZER(DnsHealthObserver)(InitializerContext*) {
HealthObserverRegistration::registerObserverFactory(
[](ServiceContext* svcCtx) { return std::make_unique<DnsHealthObserver>(svcCtx); });
}
} // namespace
} // namespace process_health
} // namespace mongo
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