GameLiftHost
Amazon GameLift dedicated servers for Blueprints and C++

Overview

GameLiftHost connects an Unreal Engine 4.27 or 5.8 dedicated server to Amazon GameLift. The server reports that it is ready, receives game sessions, validates the players that join, follows FlexMatch backfill, answers health checks and shuts down cleanly when Amazon GameLift asks it to.

• Init SDK, Process Ready, Process Ending: the whole process lifecycle, or fully automatic from the project settings.
• On Start Game Session with id, name, fleet, maximum players, IP address, DNS name, port, game properties and matchmaker data; Activate Game Session.
• Validate Player From Options for Game Mode Pre Login, or automatic validation that kicks players without a valid player session.
• Start Match Backfill / Stop Match Backfill and On Update Game Session.
• On Health Check answered instantly from the last Set Health Status value; On Process Terminate with the termination time.
• Get Fleet Role Credentials (temporary AWS keys so the server can call other AWS services) and Get Compute Certificate.

SDK callbacks arrive on the game thread. Slow calls (player session queries, backfill, credentials, certificate) run on background threads as latent nodes.

Requirements

Installation

1. Install GameLiftHost from Fab into your engine, or copy the GameLiftHost folder into your project's Plugins folder.
2. Enable GameLiftHost in Edit > Plugins and restart the editor.
3. Open Project Settings > Plugins > GameLiftHost. Enable Auto Init SDK (and Auto Process Ready) for the automatic mode, or call the nodes yourself.
4. C++ only: add PublicDependencyModuleNames.Add("GameLiftHost"); to your Build.cs.
5. Make sure your project has a dedicated server target (<Project>Server.Target.cs) and package it for Win64 or Linux.

Setting up Amazon GameLift

Managed EC2 fleet

1. Package the dedicated server: Platforms > Linux (or Windows) with the Server target, Shipping or Development configuration.
2. In the project settings enable Auto Init SDK and Auto Process Ready (or call Init SDK with an empty Anywhere struct and Process Ready once the map is loaded). On managed fleets every connection value comes from the environment.
3. Upload the packaged folder as a build:

   aws gamelift upload-build --name MyGame --build-version 1.0 --build-root "C:/Packaged/LinuxServer" --operating-system AMAZON_LINUX_2023 --server-sdk-version 5.6.1 --region us-east-1

   Use WINDOWS_2022 for a Win64 server.
4. Create a fleet from the build. Launch path /local/game/MyGame/Binaries/Linux/MyGameServer (Windows: C:\game\MyGame\Binaries\Win64\MyGameServer.exe) with parameters -log -port=7777. For several server processes per instance give each its own port (-port=7777, -port=7778, ...) and open the UDP port range in the fleet's inbound permissions.
5. When the fleet is active, game sessions are created by your backend or matchmaker and arrive in On Start Game Session.

Anywhere fleet (testing on your own PC)

1. Create a custom location and an Anywhere fleet:

   aws gamelift create-location --location-name custom-devpc
   aws gamelift create-fleet --name MyGameDev --compute-type ANYWHERE --locations "Location=custom-devpc"

2. Register your PC as a compute. Note GameLiftServiceSdkEndpoint in the answer (the WebSocket URL):

   aws gamelift register-compute --compute-name DevPC --fleet-id fleet-1234 --ip-address 127.0.0.1 --location custom-devpc

3. Get an auth token (short-lived: get a new one for every run):

   aws gamelift get-compute-auth-token --fleet-id fleet-1234 --compute-name DevPC

4. Start the server with the values on the command line:

   MyGameServer.exe -log -port=7777 -GLHWebSocketUrl=wss://us-east-1.api.amazongamelift.com -GLHAuthToken=<token> -GLHFleetId=fleet-1234 -GLHHostId=DevPC

   Or from the editor: fill Anywhere Web Socket Url / Fleet Id / Host Id in the settings, enable Allow Outside Dedicated Server, and play with Net Mode: Play As Client (the in-editor dedicated server initializes the SDK). The auth token is never saved: pass -GLHAuthToken= as an extra editor launch argument or set it on the Init SDK node at runtime.
5. Create a game session and a player session to join it:

   aws gamelift create-game-session --fleet-id fleet-1234 --location custom-devpc --maximum-player-session-count 4
   aws gamelift create-player-session --game-session-id <game session arn> --player-id player1

   Then open 127.0.0.1:7777 with the option PlayerSessionId=<id> from a game client.

Fleet role for Get Fleet Role Credentials

Create the fleet with --instance-role-arn pointing at an IAM role that Amazon GameLift may assume, and give the role only the permissions your server needs (for example one DynamoDB table or one S3 prefix). Trust policy of the role:

{
  "Version": "2012-10-17",
  "Statement": [{
    "Effect": "Allow",
    "Principal": { "Service": "gamelift.amazonaws.com" },
    "Action": "sts:AssumeRole"
  }]
}

Get Fleet Role Credentials with that role ARN returns temporary keys for any AWS SDK or signed HTTP request. It works on managed EC2 and container fleets (not on Anywhere computes).

Quick start

Blueprint (Game Instance or Game Mode)

1. Enable Auto Init SDK, Auto Process Ready and Auto Validate Players in the settings.
2. On Begin Play get the GameLiftHost Subsystem and bind On Start Game Session.
3. In the event read Game Session > Game Properties (for example map or mode), set up the match, then call Activate Game Session. Players can join from now on.
4. Bind On Process Terminate: save results, tell players, then call Process Ending with Request Exit enabled.
5. When the match is over call Process Ending with Request Exit as well: Amazon GameLift starts a fresh process for the next game session.

Manual order

Init SDK → Process Ready → On Start Game Session → Activate Game Session → Accept Player Session per joining player → Remove Player Session per leaving player → Process Ending → exit.

Validating players

Every player gets a player session (id psess-...) from Amazon GameLift before connecting and sends it in the join options. The server accepts it once; unknown, reused or expired ids are rejected. Reserved player sessions time out if the player does not connect within 60 seconds.

C++ Game Mode: Pre Login

#include "GameLiftHostSubsystem.h"

void AMyGameMode::PreLogin(const FString& Options, const FString& Address, const FUniqueNetIdRepl& UniqueId, FString& ErrorMessage)
{
    Super::PreLogin(Options, Address, UniqueId, ErrorMessage);
    UGameLiftHostSubsystem* GameLift = GetGameInstance()->GetSubsystem<UGameLiftHostSubsystem>();
    if (ErrorMessage.IsEmpty() && GameLift && GameLift->IsSdkReady())
    {
        FString PlayerSessionId;
        GameLift->ValidatePlayerFromOptions(Options, PlayerSessionId, ErrorMessage); // non-empty ErrorMessage rejects the join
    }
}

void AMyGameMode::Logout(AController* Exiting)
{
    UGameLiftHostSubsystem* GameLift = GetGameInstance()->GetSubsystem<UGameLiftHostSubsystem>();
    const FString PlayerSessionId = UGameLiftHostSubsystem::GetPlayerSessionId(Cast<APlayerController>(Exiting));
    if (GameLift && !PlayerSessionId.IsEmpty())
    {
        FGameLiftHostError Error;
        GameLift->RemovePlayerSession(PlayerSessionId, Error);
    }
    Super::Logout(Exiting);
}

Blueprint-only projects

Pre Login cannot be overridden in Blueprint. Enable Auto Validate Players: right after a remote player logs in the plugin reads PlayerSessionId from the join URL, accepts it, and kicks the player with the error text when it is missing or invalid. The player session is removed again when the player leaves. Get Player Session Id returns the id of any connected player controller.

Game clients

GameLiftHost is the server half. The game client needs a player session and the address of the game session, which come from Amazon GameLift's client-side APIs (StartMatchmaking, StartGameSessionPlacement, CreateGameSession, CreatePlayerSession) - called from your own backend, or from a game-client matchmaking / session plugin. Any of them works with this plugin as long as the client finally joins with:

Open Level (by Name):  Level Name = "<IpAddress or DnsName>:<Port>"   Options = "PlayerSessionId=<psess-...>"
C++:                   PlayerController->ClientTravel(TEXT("203.0.113.10:7777?PlayerSessionId=psess-1234"), TRAVEL_Absolute);

Matchmaking with FlexMatch delivers the teams and player attributes to the server in Game Session > Matchmaker Data (JSON). Use them to place players in teams and, when players leave, to call Start Match Backfill.

Events

Bind them on the GameLiftHost Subsystem (Get GameLiftHost Subsystem). They always fire on the game thread.

Functions

Members of the GameLiftHost Subsystem. Calls that can fail return true/false and an Error (Code + Message).

Latent nodes

These calls wait for Amazon GameLift, so they run on a background thread and fire exactly one final pin on the game thread.

C++ API

// Build.cs: PublicDependencyModuleNames.Add("GameLiftHost");
#include "GameLiftHostSubsystem.h"

UGameLiftHostSubsystem* GameLift = GetGameInstance()->GetSubsystem<UGameLiftHostSubsystem>();
GameLift->OnStartGameSession.AddDynamic(this, &AMyGameMode::HandleGameSession);

FGameLiftHostError Error;
if (GameLift->InitSdk(FGameLiftHostServerParameters(), Error) && GameLift->ProcessReady(0, TArray<FString>(), Error))
{
    // waiting for a game session
}

// Background calls: the callback runs on the game thread, Error.Code is empty on success.
UGameLiftHostSubsystem::GetFleetRoleCredentialsAsync(TEXT("arn:aws:iam::123456789012:role/MyGameServer"), FString(),
    FGameLiftHostNativeCredentials::CreateLambda([](const FGameLiftHostRoleCredentials& Credentials, const FGameLiftHostError& Error)
    {
    }));

Also available: DescribePlayerSessionsAsync, StartMatchBackfillAsync, StopMatchBackfillAsync, GetComputeCertificateAsync, ResolveServerPort and IsHostingAllowed.

Types

Settings

Project Settings > Plugins > GameLiftHost (saved to DefaultGame.ini).

Command line overrides (Anywhere): -GLHWebSocketUrl=, -GLHAuthToken=, -GLHFleetId=, -GLHHostId=, -GLHProcessId=.

Troubleshooting

Credits

© 2026 Alpha XP — alphaxp.net · Support: support@alphaxp.net. Includes the Amazon GameLift Server SDK for C++ 5.6.1 (Apache License 2.0) with asio (Boost Software License 1.0), websocketpp (BSD-3-Clause), RapidJSON (MIT), spdlog and fmt (MIT), concurrentqueue (Simplified BSD / Boost Software License) and OpenSSL 1.1.1 (OpenSSL License). Built and verified for Unreal Engine 4.27 and 5.8.