cf.yml

AWSTemplateFormatVersion: "2010-09-09"
Description: Minecraft Spot Price Server via Docker / ECS
Parameters:

  ECSAMI:
    Description: AWS ECS AMI ID
    Type: AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>
    Default: /aws/service/ecs/optimized-ami/amazon-linux-2/recommended/image_id

  ServerState:
    Type: String
    Description: "Running: A spot instance will launch shortly after setting this parameter; your Minecraft server should start within 5-10 minutes of changing this parameter (once UPDATE_IN_PROGRESS becomes UPDATE_COMPLETE). Stopped: Your spot instance (and thus Minecraft container) will be terminated shortly after setting this parameter."
    Default: Running
    AllowedValues: 
    - Running
    - Stopped

  InstanceType:
    Type: String
    Description: "t3.medium is a good cost effective instance, 1 VCPU and 3.75 GB of RAM with moderate network performance. Change at your discretion. https://aws.amazon.com/ec2/instance-types/."
    Default: t3.medium

  SpotPrice:
    Type: String
    Description: "A t3.medium shouldn't cost more than a cent per hour. Note: Leave this blank to use on-demand pricing."
    Default: "0.05"

  KeyPairName:
    Type: String
    Description: (Optional - An empty value disables this feature)
    Default: ''

  YourIp:
    Type: String
    Description: (Optional - An empty value disables this feature)
    Default: ''

  HostedZoneId:
    Type: String
    Description: (Optional - An empty value disables this feature) If you have a hosted zone in Route 53 and wish to set a DNS record whenever your Minecraft instance starts, supply the hosted zone ID here.
    Default: ''

  RecordName:
    Type: String
    Description: (Optional - An empty value disables this feature) If you have a hosted zone in Route 53 and wish to set a DNS record whenever your Minecraft instance starts, supply the name of the record here (e.g. minecraft.mydomain.com).
    Default: ''

  MinecraftImageTag:
    Type: String
    Description: "Java version (Examples include latest, adopt13, openj9, etc) Refer to tag descriptions available here: https://github.com/itzg/docker-minecraft-server)"
    Default: 'latest'

  MinecraftTypeTag:
    Type: String
    Description: "(Examples include SPIGOT, BUKKIT, TUINITY, etc) Refer to tag descriptions available here: https://github.com/itzg/docker-minecraft-server)"

  AdminPlayerNames:
    Type: String
    Description: Op/Administrator Players
    Default: ''

  Difficulty:
    Type: String
    Description: Examples include peaceful, easy (default), normal, and hard
    Default: ''

  Whitelist:
    Type: String
    Description: Usernames of your friends
    Default: ''

Metadata:
  AWS::CloudFormation::Interface:
    ParameterGroups:
      - Label: 
          default: Essential Configuration
        Parameters:
        - ServerState
        - InstanceType
        - SpotPrice
      - Label:
          default: Server Settings
        Parameters:
        - MinecraftImageTag
      - Label:
          default: Optional Server Settings
        Parameters:
        - MinecraftTypeTag
        - AdminPlayerNames
        - Difficulty
        - Whitelist
      - Label: 
          default: Optional Remote Access (SSH) Configuration
        Parameters:
        - KeyPairName
        - YourIp
      - Label: 
          default: Optional DNS Configuration
        Parameters:
        - HostedZoneId
        - RecordName
    ParameterLabels:
      ServerState:
        default: "Update this parameter to shut down / start up your Minecraft server as required to save on cost. Takes a few minutes to take effect."
      InstanceType:
        default: "Which instance type? You must make sure this is available in your region! https://aws.amazon.com/ec2/pricing/on-demand/"
      SpotPrice:
        default: "Maximum spot price per hour? Leave blank to disable spot pricing."
      MinecraftImageTag:
        default: "Which version of Minecraft do you want to launch?"
      MinecraftTypeTag:
        default: "Which type of Minecraft do you want to launch?"
      AdminPlayerNames:
        default: "A comma delimited list (no spaces) of player names to be admins"
      Difficulty:
        default: "Which difficulty?"
      Whitelist:
        default: "A comma delimited list (no spaces) of player names"
      KeyPairName:
        default: "If you wish to access the instance via SSH, select a Key Pair to use. https://console.aws.amazon.com/ec2/v2/home?#KeyPairs:sort=keyName"
      YourIp:
        default: "If you wish to access the instance via SSH, provide your public IP address."
      HostedZoneId:
        default: "If you have a hosted zone in Route 53 and wish to update a DNS record whenever your Minecraft instance starts, supply the hosted zone ID here."
      RecordName:
        default: "If you have a hosted zone in Route 53 and wish to set a DNS record whenever your Minecraft instance starts, supply a record name here (e.g. minecraft.mydomain.com)."

Conditions:
  MinecraftTypeTagProvided: !Not [ !Equals [ !Ref MinecraftTypeTag, '' ] ]
  AdminPlayerNamesProvided: !Not [ !Equals [ !Ref AdminPlayerNames, '' ] ]
  DifficultyProvided: !Not [ !Equals [ !Ref Difficulty, '' ] ]
  WhitelistProvided: !Not [ !Equals [ !Ref Whitelist, '' ] ]
  KeyPairNameProvided: !Not [ !Equals [ !Ref KeyPairName, '' ] ]
  IpAddressProvided: !Not [ !Equals [ !Ref YourIp, '' ] ]
  DnsConfigEnabled: !And [ !Not [ !Equals [ !Ref HostedZoneId, '' ] ], !Not [ !Equals [ !Ref RecordName, '' ] ] ]
  SpotPriceProvided: !Not [ !Equals [ !Ref SpotPrice, '' ] ]


Mappings:
  ServerState:
    Running:
      DesiredCapacity: 1
    Stopped:
      DesiredCapacity: 0

Resources:

  # ====================================================
  # BASIC VPC
  # ====================================================

  Vpc: 
    Type: AWS::EC2::VPC
    Properties: 
      CidrBlock: 10.100.0.0/26
      EnableDnsSupport: true
      EnableDnsHostnames: true

  SubnetA:
    Type: AWS::EC2::Subnet
    Properties:
      AvailabilityZone: !Select 
      - 0
      - !GetAZs 
        Ref: 'AWS::Region'
      CidrBlock: !Select [ 0, !Cidr [ 10.100.0.0/26, 4, 4 ] ]
      VpcId: !Ref Vpc  

  SubnetARoute:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties: 
      RouteTableId: !Ref RouteTable
      SubnetId: !Ref SubnetA

  SubnetBRoute:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties: 
      RouteTableId: !Ref RouteTable
      SubnetId: !Ref SubnetB  

  SubnetB:
    Type: AWS::EC2::Subnet
    Properties:
      AvailabilityZone: !Select 
      - 1
      - !GetAZs 
        Ref: 'AWS::Region'
      CidrBlock: !Select [ 1, !Cidr [ 10.100.0.0/26, 4, 4 ] ]
      VpcId: !Ref Vpc

  InternetGateway:
    Type: AWS::EC2::InternetGateway
    Properties: {}

  InternetGatewayAttachment:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties: 
      InternetGatewayId: !Ref InternetGateway
      VpcId: !Ref Vpc

  RouteTable:
    Type: AWS::EC2::RouteTable
    Properties: 
      VpcId: !Ref Vpc    

  Route:
    Type: AWS::EC2::Route
    Properties: 
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref InternetGateway
      RouteTableId: !Ref RouteTable

  # ====================================================
  # EFS FOR PERSISTENT DATA
  # ====================================================

  Efs:
    Type: AWS::EFS::FileSystem
    Properties: {}

  MountA:
    Type: AWS::EFS::MountTarget
    Properties:
      FileSystemId: !Ref Efs
      SecurityGroups:
      - !Ref EfsSg
      SubnetId: !Ref SubnetA

  MountB:
    Type: AWS::EFS::MountTarget
    Properties:
      FileSystemId: !Ref Efs
      SecurityGroups:
      - !Ref EfsSg
      SubnetId: !Ref SubnetB

  EfsSg:
    Type: AWS::EC2::SecurityGroup
    Properties: 
      GroupName: !Sub "${AWS::StackName}-efs"
      GroupDescription: !Sub "${AWS::StackName}-efs"
      SecurityGroupIngress:
      - FromPort: 2049
        ToPort: 2049
        IpProtocol: tcp
        SourceSecurityGroupId: !Ref Ec2Sg
      VpcId: !Ref Vpc
      
  # ====================================================
  # INSTANCE CONFIG
  # ====================================================

  Ec2Sg:
    Type: AWS::EC2::SecurityGroup
    Properties: 
      GroupName: !Sub "${AWS::StackName}-ec2"
      GroupDescription: !Sub "${AWS::StackName}-ec2"
      SecurityGroupIngress:
      - !If
        - IpAddressProvided 
        - FromPort: 22
          ToPort: 22
          IpProtocol: tcp
          CidrIp: !Sub "${YourIp}/32"
        - !Ref 'AWS::NoValue'
      - FromPort: 25565
        ToPort: 25565
        IpProtocol: tcp
        CidrIp: 0.0.0.0/0
      VpcId: !Ref Vpc

  LaunchConfiguration:
    Type: AWS::AutoScaling::LaunchConfiguration
    Properties:
      AssociatePublicIpAddress: true
      IamInstanceProfile: !Ref InstanceProfile
      ImageId: !Ref ECSAMI
      InstanceType: !Ref InstanceType
      KeyName: 
        !If [ KeyPairNameProvided, !Ref KeyPairName, !Ref 'AWS::NoValue' ]
      SecurityGroups:
      - !Ref Ec2Sg
      SpotPrice: !If [ SpotPriceProvided, !Ref SpotPrice, !Ref 'AWS::NoValue' ]
      UserData:
        Fn::Base64: !Sub |
          #!/bin/bash -xe
          yum install -y amazon-efs-utils
          mkdir /opt/minecraft
          mount -t efs ${Efs}:/ /opt/minecraft
          chown 845:845 /opt/minecraft
          echo ECS_CLUSTER=${EcsCluster} >> /etc/ecs/ecs.config          

  AutoScalingGroup:
    Type: AWS::AutoScaling::AutoScalingGroup
    DependsOn:
    - MountA
    - MountB
    Properties:
      AutoScalingGroupName: !Sub "${AWS::StackName}-asg"
      DesiredCapacity: !FindInMap [ ServerState, !Ref ServerState, DesiredCapacity ]
      LaunchConfigurationName: !Ref LaunchConfiguration
      MaxSize: !FindInMap [ ServerState, !Ref ServerState, DesiredCapacity ]
      MinSize: !FindInMap [ ServerState, !Ref ServerState, DesiredCapacity ]
      VPCZoneIdentifier:
        - !Ref SubnetA
        - !Ref SubnetB

  InstanceRole:
    Type: AWS::IAM::Role
    Properties: 
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
        - Effect: Allow
          Principal:
            Service:
            - ec2.amazonaws.com
          Action:
          - sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AmazonEC2ContainerServiceforEC2Role
      Policies:
        - PolicyName: root
          PolicyDocument: 
            Version: "2012-10-17"
            Statement: 
              - Effect: "Allow"
                Action: "route53:*"
                Resource: "*"

  InstanceProfile:
    Type: AWS::IAM::InstanceProfile
    Properties: 
      Roles:
        - !Ref InstanceRole

  EcsCluster:
    Type: AWS::ECS::Cluster
    Properties:
      ClusterName: !Sub "${AWS::StackName}-cluster"

  EcsService:
    Type: AWS::ECS::Service
    Properties: 
      Cluster: !Ref EcsCluster
      DesiredCount: !FindInMap [ ServerState, !Ref ServerState, DesiredCapacity ]
      ServiceName: !Sub "${AWS::StackName}-ecs-service"
      TaskDefinition: !Ref EcsTask  
      DeploymentConfiguration:
        MaximumPercent: 100
        MinimumHealthyPercent: 0

  EcsTask:
    Type: AWS::ECS::TaskDefinition
    Properties: 
      Volumes:
      - Host:
          SourcePath: /opt/minecraft
        Name: minecraft
      ContainerDefinitions:      
        - Name: minecraft
          MemoryReservation: 1024
          Image: !Sub "itzg/minecraft-server:${MinecraftImageTag}"
          PortMappings:
          - ContainerPort: 25565
            HostPort: 25565
            Protocol: tcp
          MountPoints:
          - ContainerPath: /data
            SourceVolume: minecraft
            ReadOnly: false
          Environment:
            - Name: "EULA"
              Value: "TRUE"
            - !If
              - MinecraftTypeTagProvided
              - Name: "TYPE"
                Value: !Sub "${MinecraftTypeTag}"
              - !Ref 'AWS::NoValue'
            - !If
              - AdminPlayerNamesProvided
              - Name: "OPS"
                Value: !Sub "${AdminPlayerNames}"
              - !Ref 'AWS::NoValue'
            - !If
              - DifficultyProvided
              - Name: "DIFFICULTY"
                Value: !Sub "${Difficulty}"
              - !Ref 'AWS::NoValue'
            - !If
              - WhitelistProvided
              - Name: "WHITELIST"
                Value: !Sub "${Whitelist}"
              - !Ref 'AWS::NoValue'

  # ====================================================
  # SET DNS RECORD
  # ====================================================

  SetDNSRecordLambdaRole:
    Type: AWS::IAM::Role
    Condition: DnsConfigEnabled
    Properties: 
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
        - Effect: Allow
          Principal:
            Service:
            - lambda.amazonaws.com
          Action:
          - sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
      Policies:
        - PolicyName: root
          PolicyDocument: 
            Version: "2012-10-17"
            Statement: 
              - Effect: "Allow"
                Action: "route53:*"
                Resource: "*"
              - Effect: "Allow"
                Action: "ec2:DescribeInstance*"
                Resource: "*"

  SetDNSRecordLambda:
    Type: "AWS::Lambda::Function"
    Condition: DnsConfigEnabled
    Properties: 
      Environment:
        Variables:
          HostedZoneId: !Ref HostedZoneId
          RecordName: !Ref RecordName
      Code:
        ZipFile: |
          import boto3
          import os
          def handler(event, context):
            new_instance = boto3.resource('ec2').Instance(event['detail']['EC2InstanceId'])
            boto3.client('route53').change_resource_record_sets(
              HostedZoneId= os.environ['HostedZoneId'],
              ChangeBatch={
                  'Comment': 'updating',
                  'Changes': [
                      {
                          'Action': 'UPSERT',
                          'ResourceRecordSet': {
                              'Name': os.environ['RecordName'],
                              'Type': 'A',
                              'TTL': 60,
                              'ResourceRecords': [
                                  {
                                      'Value': new_instance.public_ip_address
                                  },
                              ]
                          }
                      },
                  ]
              })
      Description: Sets Route 53 DNS Record for Minecraft
      FunctionName: !Sub "${AWS::StackName}-set-dns"
      Handler: index.handler
      MemorySize: 128
      Role: !GetAtt SetDNSRecordLambdaRole.Arn
      Runtime: python3.7
      Timeout: 20

  LaunchEvent:
    Type: AWS::Events::Rule
    Condition: DnsConfigEnabled
    Properties: 
      EventPattern:
        source:
        - aws.autoscaling
        detail-type:
        - EC2 Instance Launch Successful
        detail:
          AutoScalingGroupName:
          - !Ref AutoScalingGroup
      Name: !Sub "${AWS::StackName}-instance-launch"
      State: ENABLED
      Targets:
        - Arn: !GetAtt SetDNSRecordLambda.Arn
          Id: !Sub "${AWS::StackName}-set-dns"

  LaunchEventLambdaPermission:
    Type: AWS::Lambda::Permission
    Condition: DnsConfigEnabled
    Properties: 
      Action: lambda:InvokeFunction
      FunctionName: !GetAtt SetDNSRecordLambda.Arn
      Principal: events.amazonaws.com
      SourceArn: !GetAtt LaunchEvent.Arn

Outputs:
  CheckInstanceIp:
    Description: To find your Minecraft instance IP address, visit the following link. Click on the instance to find its Public IP address.
    Value: !Sub "https://${AWS::Region}.console.aws.amazon.com/ec2/v2/home?region=${AWS::Region}#Instances:tag:aws:autoscaling:groupName=${AutoScalingGroup};sort=tag:Name"