Method _registerSlave

src/master/master.cpp:6297–6456

void Master::_registerSlave(
    const UPID& pid,
    RegisterSlaveMessage&& registerSlaveMessage,
    const Option<Principal>& principal,
    const Future<bool>& authorized)
{
  CHECK(!authorized.isDiscarded());
  CHECK(slaves.registering.contains(pid));

  const SlaveInfo& slaveInfo = registerSlaveMessage.slave();

  Option<string> authorizationError = None();

  if (authorized.isFailed()) {
    authorizationError = "Authorization failure: " + authorized.failure();
  } else if (!authorized.get()) {
    authorizationError =
      "Not authorized to register agent providing resources "
      "'" + stringify(Resources(slaveInfo.resources())) + "' " +
      (principal.isSome()
       ? "with principal '" + stringify(principal.get()) + "'"
       : "without a principal");
  }

  if (authorizationError.isSome()) {
    LOG(WARNING) << "Refusing registration of agent at " << pid
                 << " (" << slaveInfo.hostname() << ")"
                 << ": " << authorizationError.get();

    slaves.registering.erase(pid);
    return;
  }

  VLOG(1) << "Authorized registration of agent at " << pid
          << " (" << slaveInfo.hostname() << ")";

  MachineID machineId;
  machineId.set_hostname(slaveInfo.hostname());
  machineId.set_ip(stringify(pid.address.ip));

  // Slaves are not allowed to register while the machine they are on is in
  // `DOWN` mode.
  if (machines.contains(machineId) &&
      machines[machineId].info.mode() == MachineInfo::DOWN) {
    LOG(WARNING) << "Refusing registration of agent at " << pid
                 << " because the machine '" << machineId << "' that it is "
                 << "running on is `DOWN`";

    ShutdownMessage message;
    message.set_message("Machine is `DOWN`");
    send(pid, message);

    slaves.registering.erase(pid);
    return;
  }

  // Ignore registration attempts by agents running old Mesos versions.
  // We expect that the agent's version is in SemVer format; if the