Nakama and Amazon GameLift Integration

Nakama Fleet Manager implementation for Amazon GameLift.

Introduction

The fleetmanager package in this repository implements Nakama's Go runtime Fleet Manager interface to interact with an existing Amazon Gamelift Fleet.

This enables the use of Nakama's social gameplay and matchmaking features for GameLift Game Session discovery and creation, facilitating the process of Fleet Management orchestration to direct players to existing or new Game Sessions as needed.

Prerequisites

The Nakama GameLift Fleet Manager expects a GameLift Fleet to be up and running with a specific setup, including:

• A Fleet Alias;
• A Placement Queue;
  • An SNS Topic to publish Placement Events;
• An SQS Queue subscribed to the above Topic;
• Invocation of status update RPCs exposed by the Fleet Manager implementation.

Follow our setup guide to create a minimal test Fleet deployment on AWS, with instructions on how to set up the above.

Installation

To add the GameLift Fleet Manager implementation to your Nakama Go plugin project use the Go command:

go get github.com/heroiclabs/nakama-gamelift/fleetmanager

This will add it to your project's go.mod dependencies.

Usage

The fleetmanager instance has to be created within your Nakama plugin InitModule global function and then be registered through the runtime.Initializer's exported RegisterFleetManager() function.

Registration

glfm, err := fleetmanager.NewGameLiftFleetManager(ctx, logger, db, initializer, nk, cfg)
if err != nil {
    return err
}

if err = initializer.RegisterFleetManager(glfm); err != nil {
    logger.WithField("error", err).Error("failed to register amazon gamelift fleet manager")
    return err
}

Access the Fleet Manager

Once registered, it can be retrieved throughout your Nakama plugin code via the runtime.NakamaModule GetFleetManager() function:

fm := nk.GetFleetManager() // If fm is nil the FleetManager was not registered.

The fm instance can then be used to list or create Game Sessions.

Create

Notice that Create receives a callback function as part of its signature - the creation process is asynchronous, so the callback is invoked once the creation process either succeeds, times-out or fails. The callback can be used to notify any interested parties on the status of the creation process:

var callback runtime.FmCreateCallbackFn = func(status runtime.FmCreateStatus, instanceInfo *runtime.InstanceInfo, sessionInfo []*runtime.SessionInfo, metadata map[string]any, createErr error) {
// createErr is not nil only if status is != runtime.CreateSuccess.
// the original GameLift Placement Event can be retrieved from `metadata` under the 'event' key.
switch status {
    case runtime.CreateSuccess:
        // Create was successful, instanceInfo contains the instance information for player connection.
        // sessionInfo contains Player Session info if a list of userIds is passed to the Create function.
        info, _ := json.Marshal(instanceInfo)
        logger.Info("GameLift instance created: %s", info)
        // Notify any interested party.
        return
    case runtime.CreateTimeout:
        // Amazon GameLift was not able to successfully create the placed Game Session request within the timeout
        // (configurable in the placement queue).
        // The client should be notified to either reattempt to find an available Game Session or retry creation.
        info, _ := json.Marshal(instanceInfo)
        logger.Info("GameLift instance created: %s", info)
        // Notify any interested party.
        return
    default:
        // The request failed to be placed.
        logger.WithField("error", createErr.Error()).Error("Failed to create GameLift instance")
        // Notify any interested party.
        return
    }
}

// maxPlayers: Maximum number of players supported by the game session.
maxPlayers := 10
// playerIds - Optional: Reserves a Player Session for each userId. The reservation expires after 60s if the client doesn't connect.
playerIds := []string{userId}
// metadata - Optional: Can contain the following keys: GameSessionDataKey, GamePropertiesKey and GameSessionNameKey.
// Expects the value of GameSessionDataKey and GameSessionNameKey to be strings. GamePropertiesKey's value should be a map[string]string.
metadata := map[string]any{GamePropertiesKey: map[string]string{"key1":"value1"}}
// latencies - Optional: - A list of latencies to different aws regions, per userId, experienced from the client.
latencies := []runtime.FleetUserLatencies{{
    UserId:                userId,
    LatencyInMilliseconds: 100,
    RegionIdentifier:      "us-east-1",
}}

err = fm.Create(ctx, maxPlayers, playerIds, latencies, metadata, callback)

List

To query for existing Game Sessions, List can be used with the Query Syntax:

query := "+value.playerCount:2" // Query to list Game Sessions currently containing 2 Player Sessions. An empty query will list all Game Sessions.
limit := 10 // Number of results per page (does not apply if query is != "").
cursor := "" // Pagination cursor.
instances, nextCursor, err := fm.List(ctx, query, limit, cursor)

Get

Get the information of a Game Session:

id := "<Game Session ARN>"
instance, err := fm.Get(ctx, id)

Join

Reserve a seat on an existing Game Session and retrieve the corresponding Player Session needed for a client to connect to it:

id := "<game session ARN>"
userIds := []string{userId}
metadata := map[string]string{
  userId: "<player data>",
} // metadata is optional. It can be used to set an arbitrary string that can be retrieved from the Game Session. Each key needs to match an userId present in userIds, otherwise it is ignored.
joinInfo, err := fm.Join(ctx, id string, userIds []string, metadata map[string]string)

Delete

Delete should be used to remove an InstanceInfo data of a Game Session that was terminated on GameLift:

id := "<game session ARN>"
err := fm.Delete(ctx, id)

Configuration

The fleetmanager instance expects a number of required configurations to be provided on creation:

• AWS Key;
• AWS Secret;
• AWS Fleet Region;
• AWS Fleet Alias ID;
• AWS Fleet Placement Queue Name;
• AWS GameLift Placement Events SQS URL;

Typically, these values would be passed to Nakama via its Nakama's runtime env configuration.

Example

func InitModule(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule, initializer runtime.Initializer) error {
  env, ok := ctx.Value(runtime.RUNTIME_CTX_ENV).(map[string]string)
  if !ok {
    return fmt.Errorf("expects env ctx value to be a map[string]string")
  }

  awsAccessKey, ok := env["GL_AWS_ACCESS_KEY"]
  if !ok {
    return runtime.NewError("missing GL_AWS_ACCESS_KEY environment variable", 3)
  }

  awsSecretAccessKey, ok := env["GL_AWS_SECRET_ACCESS_KEY"]
  if !ok {
    return runtime.NewError("missing GL_AWS_SECRET_ACCESS_KEY environment variable", 3)
  }

  awsRegion, ok := env["GL_AWS_REGION"]
  if !ok {
    return runtime.NewError("missing GL_AWS_REGION environment variable", 3)
  }

  awsAliasId, ok := env["GL_AWS_ALIAS_ID"]
  if !ok {
    return runtime.NewError("missing GL_AWS_ALIAS_ID environment variable", 3)
  }

  awsPlacementQueueName, ok := env["GL_PLACEMENT_QUEUE_NAME"]
  if !ok {
    return runtime.NewError("missing GL_PLACEMENT_QUEUE_NAME environment variable", 3)
  }

  awsGameLiftPlacementEventsQueueUrl, ok := env["GL_PLACEMENT_EVENTS_SQS_URL"]
  if !ok {
    return runtime.NewError("missing GL_PLACEMENT_EVENTS_SQS_URL environment variable", 3)
  }

  cfg := fleetmanager.NewGameLiftConfig(awsAccessKey, awsSecretAccessKey, awsRegion, awsAliasId, awsPlacementQueueName, awsGameLiftPlacementEventsQueueUrl)

  glfm, err := fleetmanager.NewGameLiftFleetManager(ctx, logger, db, initializer, nk, cfg)
  if err != nil {
    return err
  }

  if err = initializer.RegisterFleetManager(glfm); err != nil {
    logger.WithField("error", err).Error("failed to register amazon gamelift fleet manager")
    return err
  }

  return nil
}

Quickstart

If you wish to start a new Nakama Go runtime plugin project using the Fleet Manager simply clone this project:

git clone https://github.com/heroiclabs/nakama-gamelift/

To run it locally using Docker follow the steps in the Docker section.

Run locally with Docker

Configuration

To connect to your existing fleet, make sure you modify all the required runtime env parameters in the local.yml file.

The plugin sample code in this repository can be loaded and run into a Nakama container using the following Docker Compose command:

docker compose up

Status Update RPCs

For Nakama to be up-to-date on the number of Player Sessions currently connected to a Game Session and for it to be aware of when a Game Session is terminated, the Game Session SDK should invoke two RPCs that are automatically exposed as part of the fleetmanager registration. These RPCs can be invoked as Server-to-Server calls.

Update RPC

• RpcId: update_instance_info

This RPC should be invoked any time a player connects or disconnects from the Game Session to update the playerCount by passing the current number of connected players.

It can also be used to update a Game Session's GameSessionName, GameSessionData or GameProperties. Updating these metadata fields allow the filtering of Game Sessions in the List function based on the properties values. Each of metadata's expected keys are optional, and only if any is present with a value will it overwrite the current value in the Nakama Storage Index. The expected RPC payload is the following:

{
  "id": "<Game Session ARN>",
  "playerCount": 10,
  "metadata": {
    "GameSessionData": "<game_session_data>",
    "GameSessionName": "<game_session_name>",
    "GameProperties": {
      "key1": "value1",
      "key2": "value2"
    }
  }
}

Delete RPC

• RpcId: delete_instance_info

This RPC should be invoked any time a Game Session terminates. The expected RPC payload is the following:

{
  "id": "<Game Session ARN>"
}