Minecraft CDK Deployment using AWS Fargate

This repo will deploy an AWS Fargate based Minecraft server that uses Route 53 to update the service and activate the Minecraft server.

Much of the work here is based on the work by doctorrat117 from minecraft-ondemand.

Overview

.env File

The .env file used by this deployment includes several variables that will be referenced later. A sample .env file is included: .env.sample and should be updated and renamed to .env.

MINECRAFT_EDITION = 'java'
SERVER_SUBDOMAIN = 'minecraft'
DOMAIN = 'example.com'
HOSTED_ZONE_ID = 'Z00000000000000000000'
MEMORY_SIZE = '8192'
CPU_SIZE = '4096'
SNS_EMAIL = 'admin@example.com'
STARTUP_MIN = '10'
SHUTDOWN_MIN = '20'
DEBUG = 'true'

A Route 53 domain and Hosted Zone ID is required for this deployment. These will be used to start the service.

Quick Start

# if using devpod on a remote host, make sure you run this so that it
# doesn't make a docker credentials helper that can't be reached
devpod context set-options default -o SSH_INJECT_DOCKER_CREDENTIALS=false
# might need to use a different authentication mechanism
aws configure
aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin 024902228242.dkr.ecr.us-east-1.amazonaws.com
yarn
yarn build
yarn deploy

Update plugins

Some of the plugins are downloaded from a 'latest' URL, so CDK doesn't know that anything has changed.

To force the container to be rebuilt and the plugins to be redownloaded, update the env with a new version:

# Change this env to force the plugins to re-download
CONTAINER_REBUILD_VERSION=v1

AWS Fargate Service

This deployment uses an AWS Fargate service to deploy two containers - the Minecraft server and a watchdog server. The Minecraft server is the reason for deploying this and will be used to play the game. The watchdog container is used to ensure that the Minecraft server is still being used.

Starting the Service

To start the service and allow someone to use the Minecraft server, a query to SERVER_SUBDOMAIN.DOMAIN will result in Route 53 updating Cloudwatch logs. This Cloudwatch log will trigger an AWS Lambda Function to set the desired-count of the Fargate service to 1.

    if desired == 0:
        ecs.update_service(
            cluster=CLUSTER,
            service=SERVICE,
            desiredCount=1,
        )
        print("Updated desiredCount to 1")
    else:
        print("desiredCount already at 1")

By setting the desired-count to 1, the containers in the ECS service will be activated and available. The AWS ECS Service includes the Minecraft server container and a watchdog container. Both of these will be started when the desired-count is set to 1.

this.service = new FargateService(this, 'FargateService', {
  serviceName: 'MineCraftService',
  cluster: this.cluster,
  capacityProviderStrategies: [
    {
      capacityProvider: 'FARGATE',
      weight: 1,
      base: 1,
    },
  ],
  taskDefinition: this.task,
  assignPublicIp: true,
  desiredCount: 0,
  vpcSubnets: { subnetType: SubnetType.PUBLIC },
  securityGroups: [props.securityGroup],
  enableExecuteCommand: true,
});

const minecraftServerContainer = this.task.addContainer(
  'MinecraftServerContainer',
  {
    image: ContainerImage.fromRegistry(props.serverConfig.image),
    environment: {
      EULA: 'TRUE',
      MEMORY: '8G',
    },
    portMappings: [
      {
        containerPort: props.serverConfig.port,
        hostPort: props.serverConfig.port,
        protocol: props.serverConfig.protocol,
      },
    ],
    essential: false,
    logging: props.serverConfig.debug
      ? new AwsLogDriver({
          logRetention: RetentionDays.THREE_DAYS,
          streamPrefix: 'minecraft',
        })
      : undefined,
  },
);

this.task.addContainer('WatchdogContainer', {
  image: ContainerImage.fromAsset(
    path.resolve(__dirname, './resources/watchdogContainer'),
  ),
  essential: true,
  environment: {
    CLUSTER: this.cluster.clusterName,
    SERVICE: 'MineCraftService',
    DNSZONE: props.subDomainHostedZoneId,
    SERVERNAME: `${props.serverSubDomain}.${props.domain}`,
    SNSTOPIC: props.snsTopic?.topicArn || '',
    STARTUPMIN: props.startupMin,
    SHUTDOWNMIN: props.shutdownMin,
  },
  logging: props.serverConfig.debug
    ? new AwsLogDriver({
        logRetention: RetentionDays.THREE_DAYS,
        streamPrefix: 'minecraft',
      })
    : undefined,
});

Stopping the Service

During normal operations, both the Minecraft container and Watchdog container will be active. The Minecraft server is used to play the game while the Watchdog server will monitor the activity of the Minecraft server. When the watchdog server determines that the Minecraft server has not been used for SHUTDOWN_MIN, the watchdog server will set the desired-count of the Fargate Service to 0. By setting the desired-count to 0, the containers will be stopped to reduce costs.

Notification

When the AWS Fargate service starts or stops, a notification is sent to SNS.

function send_notification ()
{
  [ "$1" = "startup" ] && MESSAGETEXT="${SERVICE} is online at ${SERVERNAME}"
  [ "$1" = "shutdown" ] && MESSAGETEXT="Shutting down ${SERVICE} at ${SERVERNAME}"

  ## SNS Option
  [ -n "$SNSTOPIC" ] && \
  echo "SNS topic set, sending $1 message" && \
  aws sns publish --topic-arn "$SNSTOPIC" --message "$MESSAGETEXT"
}