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A Pterodactyl server instance goes through multiple states throughout its lifecycle, from installation to deletion. Understanding these states and transitions is crucial for developing integrations and troubleshooting issues.

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Server States

Wings tracks server states using atomic strings to ensure thread-safe state management.

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Environment States

These are the core states defined in environment/environment.go:18-23: 
const (
    ProcessOfflineState  = "offline"
    ProcessStartingState = "starting"
    ProcessRunningState  = "running"
    ProcessStoppingState = "stopping"
)
State Diagram:

​
Additional Operation States

Servers also track special operation states using atomic booleans: 
// From server/server.go:63-65
installing   *system.AtomicBool
transferring *system.AtomicBool
restoring    *system.AtomicBool
These prevent conflicting operations from running simultaneously.

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Installation Process

The installation process is a critical part of a server’s lifecycle. It prepares the server environment and runs setup scripts.

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Installation Flow

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Installation Container Configuration

Installation runs in a temporary Docker container separate from the server’s runtime container: 
// From server/install.go:399-413
conf := &container.Config{
    Hostname:     "installer",
    AttachStdout: true,
    AttachStderr: true,
    AttachStdin:  true,
    OpenStdin:    true,
    Tty:          true,
    Cmd:          []string{ip.Script.Entrypoint, "/mnt/install/install.sh"},
    Image:        ip.Script.ContainerImage,
    Env:          ip.Server.GetEnvironmentVariables(),
    Labels: map[string]string{
        "Service":       "Pterodactyl",
        "ContainerType": "server_installer",
    },
}
Key Mounts:
  • /mnt/server - Server’s data directory (read-write)
  • /mnt/install - Installation script location (read-write)

​
Resource Limits During Installation

Installation containers use the higher of server limits or global installer limits: 
// From server/install.go:524-541
func (ip *InstallationProcess) resourceLimits() container.Resources {
    limits := config.Get().Docker.InstallerLimits
    cfg := c.Build
    
    if cfg.MemoryLimit < limits.Memory {
        cfg.MemoryLimit = limits.Memory
    }
    
    if limits.Cpu == 0 {
        cfg.CpuLimit = 0
    } else if cfg.CpuLimit != 0 && cfg.CpuLimit < limits.Cpu {
        cfg.CpuLimit = limits.Cpu
    }
    
    return cfg.AsContainerResources()
}
This prevents servers with very low limits from failing installation while avoiding excessive resource usage.

​
Power Actions

Power actions control the server’s running state. They are protected by an exclusive lock to prevent race conditions.

​
Power Action Types

// From server/power.go:24-29
const (
    PowerActionStart     = "start"
    PowerActionStop      = "stop"
    PowerActionRestart   = "restart"
    PowerActionTerminate = "kill"
)

​
Start Process

Starting a server involves several pre-flight checks: 
// From server/power.go:171-218
func (s *Server) onBeforeStart() error {
    // 1. Sync with Panel for latest configuration
    if err := s.Sync(); err != nil {
        return errors.WithMessage(err, "unable to sync server data")
    }
    
    // 2. Check if server is suspended
    if s.IsSuspended() {
        return ErrSuspended
    }
    
    // 3. Sync environment variables and resource limits
    s.SyncWithEnvironment()
    
    // 4. Check disk space availability
    if s.DiskSpace() > 0 {
        if err := s.Filesystem().HasSpaceErr(false); err != nil {
            return err
        }
    }
    
    // 5. Update configuration files
    s.UpdateConfigurationFiles()
    
    // 6. Set correct file permissions (if enabled)
    if config.Get().System.CheckPermissionsOnBoot {
        if err := s.Filesystem().Chown("/"); err != nil {
            return err
        }
    }
    
    return nil
}

​
Stop Process

Stopping can be done via command or signal, depending on server configuration: 
// From environment/docker/power.go:139-204
func (e *Environment) Stop(ctx context.Context) error {
    e.SetState(environment.ProcessStoppingState)
    
    // Signal-based stop
    if s.Type == remote.ProcessStopSignal {
        return e.SignalContainer(ctx, s.Value)
    }
    
    // Command-based stop (send stop command to stdin)
    if e.IsAttached() && s.Type == remote.ProcessStopCommand {
        return e.SendCommand(s.Value)
    }
    
    // Fallback to native Docker stop (SIGTERM)
    timeout := -1  // Indefinite timeout for graceful shutdown
    return e.client.ContainerStop(ctx, e.Id, container.StopOptions{Timeout: &timeout})
}

​
Restart Process

Restart is implemented as a stop followed by a start: 
// From server/power.go:137-161
case PowerActionRestart:
    // Wait for complete stop (up to 10 minutes)
    if err := s.Environment.WaitForStop(s.Context(), time.Minute*10, true); err != nil {
        return err
    }
    
    // Run pre-boot logic
    if err := s.onBeforeStart(); err != nil {
        return err
    }
    
    return s.Environment.Start(s.Context())

​
Terminate Process

Termination bypasses the power lock for emergency situations: 
// From server/power.go:108-121
if action == PowerActionTerminate {
    // Try to acquire lock but don't fail if unavailable
    if err := s.powerLock.Acquire(); err == nil {
        defer cleanup()
    } else {
        log.Warn("failed to acquire exclusive lock, ignoring for termination")
    }
}
Termination sends SIGKILL to immediately stop the container: 
// From environment/docker/power.go:311-322
func (e *Environment) Terminate(ctx context.Context, signal string) error {
    if err := e.SignalContainer(ctx, signal); err != nil {
        return errors.WithStack(err)
    }
    
    // Immediately mark as offline
    e.SetState(environment.ProcessOfflineState)
    return nil
}

​
Crash Detection and Recovery

Wings includes automatic crash detection and restart capabilities.

​
Crash Detection Logic

// From server/server.go:345-358
if (prevState == environment.ProcessStartingState || 
    prevState == environment.ProcessRunningState) && 
    s.Environment.State() == environment.ProcessOfflineState {
    
    s.Log().Info("detected server as entering a crashed state")
    
    go func(server *Server) {
        if err := server.handleServerCrash(); err != nil {
            if IsTooFrequentCrashError(err) {
                server.Log().Info("did not restart after crash")
            }
        }
    }(s)
}

​
Crash Handler

The crash handler determines if a restart should occur: 
// From server/crash.go:47-91
func (s *Server) handleServerCrash() error {
    // Skip if crash detection disabled
    if !s.Config().CrashDetectionEnabled {
        return nil
    }
    
    exitCode, oomKilled, err := s.Environment.ExitState()
    if err != nil {
        return err
    }
    
    // Clean exit code handling
    if exitCode == 0 && !oomKilled && 
       !config.Get().System.CrashDetection.DetectCleanExitAsCrash {
        return nil
    }
    
    s.PublishConsoleOutputFromDaemon("---------- Detected crash! ----------")
    s.PublishConsoleOutputFromDaemon(fmt.Sprintf("Exit code: %d", exitCode))
    s.PublishConsoleOutputFromDaemon(fmt.Sprintf("Out of memory: %t", oomKilled))
    
    // Check crash frequency
    lastCrash := s.crasher.LastCrashTime()
    timeout := config.Get().System.CrashDetection.Timeout
    
    if timeout != 0 && !lastCrash.IsZero() && 
       lastCrash.Add(time.Second*time.Duration(timeout)).After(time.Now()) {
        return &crashTooFrequent{}
    }
    
    s.crasher.SetLastCrash(time.Now())
    
    // Attempt restart
    return s.HandlePowerAction(PowerActionStart)
}
Crash Detection Configuration:
  • DetectCleanExitAsCrash - Whether exit code 0 counts as a crash
  • Timeout - Minimum seconds between crashes to allow restart
  • Setting timeout to 0 always allows restart

​
State Change Events

State changes trigger events that can be subscribed to: 
// From server/server.go:317-336
func (s *Server) OnStateChange() {
    prevState := s.resources.State.Load()
    st := s.Environment.State()
    
    // Update tracked state
    s.resources.State.Store(st)
    
    // Emit event if state changed
    if prevState != st {
        s.Log().WithField("status", st).Debug("saw server status change")
        s.Events().Publish(StatusEvent, st)
    }
    
    // Reset resource usage on offline
    if st == environment.ProcessOfflineState {
        s.resources.Reset()
        s.Events().Publish(StatsEvent, s.Proc())
    }
    
    // Handle crash detection
    // ...
}

​
Reinstallation

Reinstallation reruns the installation process without deleting server files: 
// From server/install.go:80-94
func (s *Server) Reinstall() error {
    // Ensure server is stopped
    if s.Environment.State() != environment.ProcessOfflineState {
        if err := s.Environment.WaitForStop(s.Context(), time.Second*10, true); err != nil {
            return errors.WrapIf(err, "install: failed to stop running environment")
        }
    }
    
    // Sync latest configuration
    if err := s.Sync(); err != nil {
        return errors.WrapIf(err, "install: failed to sync server state")
    }
    
    return s.install(true)  // true = reinstall flag
}

​
Transfer State

Servers being transferred between nodes have special state handling: 
// From server/install.go:146-160
func (s *Server) IsTransferring() bool {
    return s.transferring.Load()
}

func (s *Server) SetTransferring(state bool) {
    s.transferring.Store(state)
}
During transfers:
  • Server is marked as transferring
  • Power actions are blocked
  • Archive is created and sent to target node
  • Target node extracts and starts server

​
Lifecycle Events Timeline

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Next Steps

Architecture

Understand the overall system architecture

Docker Integration

Learn how Wings manages Docker containers

File Management

Explore filesystem operations

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