AWSTemplateFormatVersion: '2010-09-09'
Description: A stack for deploying containerized applications onto a cluster of EC2
             hosts using Elastic Container Service. This stack runs containers on
             hosts that are in a public VPC subnet.
Parameters:
  DesiredCapacity:
    Type: Number
    Default: '1'
    Description: Number of EC2 instances to launch in your ECS cluster.
  MaxSize:
    Type: Number
    Default: '6'
    Description: Maximum number of EC2 instances that can be launched in your ECS cluster.
  ECSAMI:
    Description: AMI ID
    Type: AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>
    Default: /aws/service/ecs/optimized-ami/amazon-linux-2/recommended/image_id
  InstanceType:
    Description: EC2 instance type
    Type: String
    Default: c4.xlarge
    AllowedValues: [t2.micro, t2.small, t2.medium, t2.large, m3.medium, m3.large,
      m3.xlarge, m3.2xlarge, m4.large, m4.xlarge, m4.2xlarge, m4.4xlarge, m4.10xlarge,
      c4.large, c4.xlarge, c4.2xlarge, c4.4xlarge, c4.8xlarge, c3.large, c3.xlarge,
      c3.2xlarge, c3.4xlarge, c3.8xlarge, r3.large, r3.xlarge, r3.2xlarge, r3.4xlarge,
      r3.8xlarge, i2.xlarge, i2.2xlarge, i2.4xlarge, i2.8xlarge]
    ConstraintDescription: Please choose a valid instance type.
  ECSKeyName:
    Type: String
    Default: gerrit-cluster-keys
    Description: EC2 key pair name the cluter's instances
  EnvironmentName:
      Description: An environment name used to build the log stream names
      Type: String
      Default: test
Mappings:
  # Hard values for the subnet masks. These masks define
  # the range of internal IP addresses that can be assigned.
  # The VPC can have all IP's from 10.0.0.0 to 10.0.255.255
  # There is the subnet which cover the ranges:
  #
  # 10.0.0.0 - 10.0.0.255
  SubnetConfig:
    VPC:
      CIDR: '10.0.0.0/16'
    PublicOne:
      CIDR: '10.0.0.0/24'
Resources:
  VPC:
    Type: AWS::EC2::VPC
    Properties:
      EnableDnsSupport: true
      EnableDnsHostnames: true
      CidrBlock: !FindInMap ['SubnetConfig', 'VPC', 'CIDR']

  # Public subnets, where containers can have public IP addresses
  PublicSubnetOne:
    Type: AWS::EC2::Subnet
    Properties:
      AvailabilityZone:
         Fn::Select:
         - 0
         - Fn::GetAZs: {Ref: 'AWS::Region'}
      VpcId: !Ref 'VPC'
      CidrBlock: !FindInMap ['SubnetConfig', 'PublicOne', 'CIDR']
      MapPublicIpOnLaunch: true

  # Setup networking resources for the public subnets. Containers
  # in the public subnets have public IP addresses and the routing table
  # sends network traffic via the internet gateway.
  InternetGateway:
    Type: AWS::EC2::InternetGateway
  GatewayAttachement:
    Type: AWS::EC2::VPCGatewayAttachment
    Properties:
      VpcId: !Ref 'VPC'
      InternetGatewayId: !Ref 'InternetGateway'
  PublicRouteTable:
    Type: AWS::EC2::RouteTable
    Properties:
      VpcId: !Ref 'VPC'
  PublicRoute:
    Type: AWS::EC2::Route
    DependsOn: GatewayAttachement
    Properties:
      RouteTableId: !Ref 'PublicRouteTable'
      DestinationCidrBlock: '0.0.0.0/0'
      GatewayId: !Ref 'InternetGateway'
  PublicSubnetOneRouteTableAssociation:
    Type: AWS::EC2::SubnetRouteTableAssociation
    Properties:
      SubnetId: !Ref PublicSubnetOne
      RouteTableId: !Ref PublicRouteTable

  # ECS Resources
  ECSCluster:
    Type: AWS::ECS::Cluster

  EcsHostSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Access to the ECS hosts that run containers
      VpcId: !Ref 'VPC'
      SecurityGroupIngress:
          # Allow access to NLB from anywhere on the internet
          - CidrIp: 0.0.0.0/0
            IpProtocol: -1

  CloudWatchLogsGroup:
      Type: AWS::Logs::LogGroup
      Properties:
          LogGroupName: !Ref AWS::StackName
          RetentionInDays: 14

  # Autoscaling group. This launches the actual EC2 instances that will register
  # themselves as members of the cluster, and run the docker containers.
  ECSAutoScalingGroup:
    Type: AWS::AutoScaling::AutoScalingGroup
    Properties:
      VPCZoneIdentifier:
        - !Ref PublicSubnetOne
      LaunchConfigurationName: !Ref 'ContainerInstances'
      MinSize: '1'
      MaxSize: !Ref 'MaxSize'
      DesiredCapacity: !Ref 'DesiredCapacity'
    CreationPolicy:
      ResourceSignal:
        Timeout: PT15M
    UpdatePolicy:
      AutoScalingReplacingUpdate:
        WillReplace: 'true'
  ContainerInstances:
    Type: AWS::AutoScaling::LaunchConfiguration
    Properties:
      ImageId: !Ref 'ECSAMI'
      SecurityGroups: [!Ref 'EcsHostSecurityGroup']
      InstanceType: !Ref 'InstanceType'
      IamInstanceProfile: !Ref 'EC2InstanceProfile'
      KeyName: !Ref ECSKeyName
      UserData:
        Fn::Base64: !Sub |
          #!/bin/bash -xe
          echo ECS_CLUSTER=${ECSCluster} >> /etc/ecs/ecs.config
          # Make sure latest version of the helper scripts are installed as per recommendation:
          # https://github.com/awsdocs/aws-cloudformation-user-guide/blob/master/doc_source/cfn-helper-scripts-reference.md#using-the-latest-version
          yum install -y aws-cfn-bootstrap nfs-utils wget
          # EFS setting
          DIR_TGT=/mnt/efs/gerrit-shared
          mkdir -p $DIR_TGT
          EC2_REGION=${AWS::Region}
          # 169.254.169.254 link-local address, valid only from the instance, to retrieve meta-data information.
          EC2_AVAIL_ZONE=`curl -s http://169.254.169.254/latest/meta-data/placement/availability-zone`
          EFS_FILE_SYSTEM_ID=${FileSystem}
          DIR_SRC=$EC2_AVAIL_ZONE.$EFS_FILE_SYSTEM_ID.efs.$EC2_REGION.amazonaws.com

          touch /home/ec2-user/echo.res
          echo $EFS_FILE_SYSTEM_ID >> /home/ec2-user/echo.res
          echo $EC2_AVAIL_ZONE >> /home/ec2-user/echo.res
          echo $EC2_REGION >> /home/ec2-user/echo.res
          echo $DIR_SRC >> /home/ec2-user/echo.res
          echo $DIR_TGT >> /home/ec2-user/echo.res
          MAX_RETRIES=20
          for i in $(seq 1 $MAX_RETRIES); do
            echo "Mounting EFS volume ($i/$MAX_RETRIES)..."
            `mount -t nfs4 -o nfsvers=4.1,hard,timeo=600,retrans=2 $DIR_SRC:/ $DIR_TGT >> /home/ec2-user/echo.res` \
              && s=0 && break || s=$? && sleep 5;
          done; (exit $s)
          mkdir -p $DIR_TGT/git
          mkdir -p $DIR_TGT/high-availability
          chown -R 1000:1000 $DIR_TGT
          cp -p /etc/fstab /etc/fstab.back-$(date +%F)
          echo -e \"$DIR_SRC:/ \t\t $DIR_TGT \t\t nfs \t\t defaults \t\t 0 \t\t 0\" | tee -a /etc/fstab
          # Get the CloudWatch Logs agent
          echo -e "
            {\"logs\":
              {\"logs_collected\":
                {\"files\":
                  {\"collect_list\":
                    [
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-2/_data/replication_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-2/replication_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-2/_data/httpd_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-2/httpd_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-2/_data/sshd_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-2/sshd_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-2/_data/gc_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-2/gc_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-2/_data/audit_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-2/audit_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-1/_data/replication_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-1/replication_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-1/_data/httpd_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-1/httpd_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-1/_data/sshd_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-1/sshd_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-1/_data/gc_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-1/gc_log\",
                      \"timezone\": \"UTC\"
                      },
                      {\"file_path\": \"/var/lib/docker/volumes/gerrit-logs-master-1/_data/audit_log\",
                      \"log_group_name\": \"${AWS::StackName}\",
                      \"log_stream_name\": \"${EnvironmentName}/{instance_id}/master-1/audit_log\",
                      \"timezone\": \"UTC\"
                      }
                    ]
                  }
                }
              }
            }" >> /home/ec2-user/gerritlogsaccess.json
          # Install the CloudWatch Logs agent
          wget https://s3.amazonaws.com/amazoncloudwatch-agent/centos/amd64/latest/amazon-cloudwatch-agent.rpm
          rpm -U ./amazon-cloudwatch-agent.rpm
          /opt/aws/amazon-cloudwatch-agent/bin/amazon-cloudwatch-agent-ctl -a fetch-config -m ec2 -c file:/home/ec2-user/gerritlogsaccess.json -s
          # Signal to CloudFormation aws-cfn-bootstrap has been correctly updated
          /opt/aws/bin/cfn-signal -e $? --stack ${AWS::StackName} --resource ECSAutoScalingGroup --region ${AWS::Region}

  EC2InstanceProfile:
    Type: AWS::IAM::InstanceProfile
    Properties:
      Path: /
      Roles: [!Ref 'EC2Role']

  # Role for the EC2 hosts. This allows the ECS agent on the EC2 hosts
  # to communciate with the ECS control plane, as well as download the docker
  # images from ECR to run on your host.
  EC2Role:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Statement:
        - Effect: Allow
          Principal:
            Service: [ec2.amazonaws.com]
          Action: ['sts:AssumeRole']
      Path: /
      Policies:
      - PolicyName: ecs-service
        PolicyDocument:
          Statement:
          - Effect: Allow
            Action:
              - 'ecs:CreateCluster'
              - 'ecs:DeregisterContainerInstance'
              - 'ecs:DiscoverPollEndpoint'
              - 'ecs:Poll'
              - 'ecs:RegisterContainerInstance'
              - 'ecs:StartTelemetrySession'
              - 'ecs:Submit*'
              - 'logs:CreateLogStream'
              - 'logs:PutLogEvents'
              - 'ecr:GetAuthorizationToken'
              - 'ecr:BatchGetImage'
              - 'ecr:GetDownloadUrlForLayer'
            Resource: '*'
  FileSystem:
    Type: AWS::EFS::FileSystem
    Properties:
      ThroughputMode: provisioned
      ProvisionedThroughputInMibps: 1024
      FileSystemTags:
        - Key: Name
          Value: "multi-master-git-repo"
  GitMountTarget:
    Type: AWS::EFS::MountTarget
    Properties:
      FileSystemId: !Ref FileSystem
      SubnetId: !Ref PublicSubnetOne
      SecurityGroups:
        - !Ref MountTargetSecurityGroup
  MountTargetSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      VpcId: !Ref 'VPC'
      GroupDescription: "Security group for mount target"
      SecurityGroupIngress:
        - IpProtocol: TCP
          FromPort: 2049
          ToPort: 2049
          CidrIp: !FindInMap ['SubnetConfig', 'PublicOne', 'CIDR']

Outputs:
  ClusterName:
    Description: The name of the ECS cluster
    Value: !Ref 'ECSCluster'
    Export:
      Name: !Join [ ':', [ !Ref 'AWS::StackName', 'ClusterName' ] ]
  VPCId:
    Description: The ID of the VPC that this stack is deployed in
    Value: !Ref 'VPC'
    Export:
      Name: !Join [ ':', [ !Ref 'AWS::StackName', 'VPCId' ] ]
  PublicSubnetOne:
    Description: Public subnet one
    Value: !Ref 'PublicSubnetOne'
    Export:
      Name: !Join [ ':', [ !Ref 'AWS::StackName', 'PublicSubnetOne' ] ]