package server import ( "context" "github.com/pkg/errors" "github.com/pterodactyl/wings/config" "golang.org/x/sync/semaphore" "os" "time" ) type PowerAction string // The power actions that can be performed for a given server. This taps into the given server // environment and performs them in a way that prevents a race condition from occurring. For // example, sending two "start" actions back to back will not process the second action until // the first action has been completed. // // This utilizes a workerpool with a limit of one worker so that all of the actions execute // in a sync manner. const ( PowerActionStart = "start" PowerActionStop = "stop" PowerActionRestart = "restart" PowerActionTerminate = "kill" ) // Checks if the power action being received is valid. func (pa PowerAction) IsValid() bool { return pa == PowerActionStart || pa == PowerActionStop || pa == PowerActionTerminate || pa == PowerActionRestart } func (pa PowerAction) IsStart() bool { return pa == PowerActionStart || pa == PowerActionRestart } // Helper function that can receive a power action and then process the actions that need // to occur for it. This guards against someone calling Start() twice at the same time, or // trying to restart while another restart process is currently running. // // However, the code design for the daemon does depend on the user correctly calling this // function rather than making direct calls to the start/stop/restart functions on the // environment struct. func (s *Server) HandlePowerAction(action PowerAction, waitSeconds ...int) error { if s.powerLock == nil { s.powerLock = semaphore.NewWeighted(1) } // Only attempt to acquire a lock on the process if this is not a termination event. We want to // just allow those events to pass right through for good reason. If a server is currently trying // to process a power action but has gotten stuck you still should be able to pass through the // terminate event. The good news here is that doing that oftentimes will get the stuck process to // move again, and naturally continue through the process. if action != PowerActionTerminate { // Determines if we should wait for the lock or not. If a value greater than 0 is passed // into this function we will wait that long for a lock to be acquired. if len(waitSeconds) > 0 && waitSeconds[0] != 0 { ctx, _ := context.WithTimeout(context.Background(), time.Second*time.Duration(waitSeconds[0])) // Attempt to acquire a lock on the power action lock for up to 30 seconds. If more // time than that passes an error will be propagated back up the chain and this // request will be aborted. if err := s.powerLock.Acquire(ctx, 1); err != nil { return errors.Wrap(err, "could not acquire lock on power state") } } else { // If no wait duration was provided we will attempt to immediately acquire the lock // and bail out with a context deadline error if it is not acquired immediately. if ok := s.powerLock.TryAcquire(1); !ok { return errors.Wrap(context.DeadlineExceeded, "could not acquire lock on power state") } } // Release the lock once the process being requested has finished executing. defer s.powerLock.Release(1) } else { // Still try to acquire the lock if terminating and it is available, just so that other power // actions are blocked until it has completed. However, if it is unavailable we won't stop // the entire process. if ok := s.powerLock.TryAcquire(1); ok { // If we managed to acquire the lock be sure to released it once this process is completed. defer s.powerLock.Release(1) } } switch action { case PowerActionStart: // Run the pre-boot logic for the server before processing the environment start. if err := s.onBeforeStart(); err != nil { return err } return s.Environment.Start() case PowerActionStop: // We're specificially waiting for the process to be stopped here, otherwise the lock is released // too soon, and you can rack up all sorts of issues. return s.Environment.WaitForStop(10*60, true) case PowerActionRestart: if err := s.Environment.WaitForStop(10*60, true); err != nil { // Even timeout errors should be bubbled back up the stack. If the process didn't stop // nicely, but the terminate argument was passed then the server is stopped without an // error being returned. // // However, if terminate is not passed you'll get a context deadline error. We could // probably handle that nicely here, but I'd rather just pass it back up the stack for now. // Either way, any type of error indicates we should not attempt to start the server back // up. return err } // Now actually try to start the process by executing the normal pre-boot logic. if err := s.onBeforeStart(); err != nil { return err } return s.Environment.Start() case PowerActionTerminate: return s.Environment.Terminate(os.Kill) } return errors.New("attempting to handle unknown power action") } // Execute a few functions before actually calling the environment start commands. This ensures // that everything is ready to go for environment booting, and that the server can even be started. func (s *Server) onBeforeStart() error { s.Log().Info("syncing server configuration with panel") if err := s.Sync(); err != nil { return errors.Wrap(err, "unable to sync server data from Panel instance") } // Disallow start & restart if the server is suspended. Do this check after performing a sync // action with the Panel to ensure that we have the most up-to-date information for that server. if s.IsSuspended() { return new(suspendedError) } // Ensure we sync the server information with the environment so that any new environment variables // and process resource limits are correctly applied. s.SyncWithEnvironment() s.PublishConsoleOutputFromDaemon("Checking server disk space usage, this could take a few seconds...") if !s.Filesystem.HasSpaceAvailable(false) { return errors.New("cannot start server, not enough disk space available") } // Update the configuration files defined for the server before beginning the boot process. // This process executes a bunch of parallel updates, so we just block until that process // is completee. Any errors as a result of this will just be bubbled out in the logger, // we don't need to actively do anything about it at this point, worst comes to worst the // server starts in a weird state and the user can manually adjust. s.PublishConsoleOutputFromDaemon("Updating process configuration files...") s.UpdateConfigurationFiles() if config.Get().System.CheckPermissionsOnBoot { s.PublishConsoleOutputFromDaemon("Ensuring file permissions are set correctly, this could take a few seconds...") // Ensure all of the server file permissions are set correctly before booting the process. if err := s.Filesystem.Chown("/"); err != nil { return errors.Wrap(err, "failed to chown root server directory during pre-boot process") } } return nil }