---
AWSTemplateFormatVersion: "2010-09-09"
Description: GitLab EKS Cluster

Parameters:

  KubernetesVersion:
    Description: The Kubernetes version to install
    Type: String
    Default: "1.20"
    AllowedValues:
      - "1.16"
      - "1.17"
      - "1.18"
      - "1.19"
      - "1.20"

  KeyName:
    Description: The EC2 Key Pair to allow SSH access to the node instances
    Type: AWS::EC2::KeyPair::KeyName

  NodeImageIdSSMParam:
    Type: "AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>"
    Default: /aws/service/eks/optimized-ami/1.17/amazon-linux-2/recommended/image_id
    Description: AWS Systems Manager Parameter Store parameter of the AMI ID for the worker node instances.

  NodeInstanceType:
    Description: EC2 instance type for the node instances
    Type: String
    Default: t3.medium
    ConstraintDescription: Must be a valid EC2 instance type
    AllowedValues:
      - t2.small
      - t2.medium
      - t2.large
      - t2.xlarge
      - t2.2xlarge
      - t3.nano
      - t3.micro
      - t3.small
      - t3.medium
      - t3.large
      - t3.xlarge
      - t3.2xlarge
      - m3.medium
      - m3.large
      - m3.xlarge
      - m3.2xlarge
      - m4.large
      - m4.xlarge
      - m4.2xlarge
      - m4.4xlarge
      - m4.10xlarge
      - m5.large
      - m5.xlarge
      - m5.2xlarge
      - m5.4xlarge
      - m5.12xlarge
      - m5.24xlarge
      - c4.large
      - c4.xlarge
      - c4.2xlarge
      - c4.4xlarge
      - c4.8xlarge
      - c5.large
      - c5.xlarge
      - c5.2xlarge
      - c5.4xlarge
      - c5.9xlarge
      - c5.18xlarge
      - i3.large
      - i3.xlarge
      - i3.2xlarge
      - i3.4xlarge
      - i3.8xlarge
      - i3.16xlarge
      - r3.xlarge
      - r3.2xlarge
      - r3.4xlarge
      - r3.8xlarge
      - r4.large
      - r4.xlarge
      - r4.2xlarge
      - r4.4xlarge
      - r4.8xlarge
      - r4.16xlarge
      - x1.16xlarge
      - x1.32xlarge
      - p2.xlarge
      - p2.8xlarge
      - p2.16xlarge
      - p3.2xlarge
      - p3.8xlarge
      - p3.16xlarge
      - p3dn.24xlarge
      - r5.large
      - r5.xlarge
      - r5.2xlarge
      - r5.4xlarge
      - r5.12xlarge
      - r5.24xlarge
      - r5d.large
      - r5d.xlarge
      - r5d.2xlarge
      - r5d.4xlarge
      - r5d.12xlarge
      - r5d.24xlarge
      - z1d.large
      - z1d.xlarge
      - z1d.2xlarge
      - z1d.3xlarge
      - z1d.6xlarge
      - z1d.12xlarge

  NodeAutoScalingGroupDesiredCapacity:
    Description: Desired capacity of Node Group ASG.
    Type: Number
    Default: 3

  NodeVolumeSize:
    Description: Node volume size
    Type: Number
    Default: 20

  ClusterName:
    Description: Unique name for your Amazon EKS cluster.
    Type: String

  ClusterRole:
    Description: The IAM Role to allow Amazon EKS and the Kubernetes control plane to manage AWS resources on your behalf.
    Type: String

  ClusterControlPlaneSecurityGroup:
    Description: The security groups to apply to the EKS-managed Elastic Network Interfaces that are created in your worker node subnets.
    Type: AWS::EC2::SecurityGroup::Id

  VpcId:
    Description: The VPC to use for your EKS Cluster resources.
    Type: AWS::EC2::VPC::Id

  Subnets:
    Description: The subnets in your VPC where your worker nodes will run.
    Type: List<AWS::EC2::Subnet::Id>

Metadata:

  AWS::CloudFormation::Interface:
    ParameterGroups:
      - Label:
          default: EKS Cluster
        Parameters:
          - ClusterName
          - ClusterRole
          - KubernetesVersion
          - ClusterControlPlaneSecurityGroup
      - Label:
          default: Worker Node Configuration
        Parameters:
          - NodeAutoScalingGroupDesiredCapacity
          - NodeInstanceType
          - NodeImageIdSSMParam
          - NodeVolumeSize
          - KeyName
      - Label:
          default: Worker Network Configuration
        Parameters:
          - VpcId
          - Subnets

Resources:

  Cluster:
    Type: AWS::EKS::Cluster
    Properties:
      Name: !Sub ${ClusterName}
      Version: !Sub ${KubernetesVersion}
      RoleArn: !Sub ${ClusterRole}
      ResourcesVpcConfig:
        SecurityGroupIds:
          - !Ref ClusterControlPlaneSecurityGroup
        SubnetIds: !Ref Subnets

  NodeInstanceProfile:
    Type: AWS::IAM::InstanceProfile
    Properties:
      Path: "/"
      Roles:
        - !Ref NodeInstanceRole

  NodeInstanceRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
          - Effect: Allow
            Principal:
              Service: ec2.amazonaws.com
            Action: sts:AssumeRole
      Path: "/"
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/AmazonEKSWorkerNodePolicy
        - arn:aws:iam::aws:policy/AmazonEKS_CNI_Policy
        - arn:aws:iam::aws:policy/AmazonEC2ContainerRegistryReadOnly

  NodeSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Security group for all nodes in the cluster
      VpcId: !Ref VpcId
      Tags:
        - Key: !Sub kubernetes.io/cluster/${ClusterName}
          Value: owned

  NodeSecurityGroupIngress:
    Type: AWS::EC2::SecurityGroupIngress
    DependsOn: NodeSecurityGroup
    Properties:
      Description: Allow nodes to communicate with each other
      GroupId: !Ref NodeSecurityGroup
      SourceSecurityGroupId: !Ref NodeSecurityGroup
      IpProtocol: -1
      FromPort: 0
      ToPort: 65535

  NodeSecurityGroupFromControlPlaneIngress:
    Type: AWS::EC2::SecurityGroupIngress
    DependsOn: NodeSecurityGroup
    Properties:
      Description: Allow worker Kubelets and pods to receive communication from the cluster control plane
      GroupId: !Ref NodeSecurityGroup
      SourceSecurityGroupId: !Ref ClusterControlPlaneSecurityGroup
      IpProtocol: tcp
      FromPort: 1025
      ToPort: 65535

  ControlPlaneEgressToNodeSecurityGroup:
    Type: AWS::EC2::SecurityGroupEgress
    DependsOn: NodeSecurityGroup
    Properties:
      Description: Allow the cluster control plane to communicate with worker Kubelet and pods
      GroupId: !Ref ClusterControlPlaneSecurityGroup
      DestinationSecurityGroupId: !Ref NodeSecurityGroup
      IpProtocol: tcp
      FromPort: 1025
      ToPort: 65535

  NodeSecurityGroupFromControlPlaneOn443Ingress:
    Type: AWS::EC2::SecurityGroupIngress
    DependsOn: NodeSecurityGroup
    Properties:
      Description: Allow pods running extension API servers on port 443 to receive communication from cluster control plane
      GroupId: !Ref NodeSecurityGroup
      SourceSecurityGroupId: !Ref ClusterControlPlaneSecurityGroup
      IpProtocol: tcp
      FromPort: 443
      ToPort: 443

  ControlPlaneEgressToNodeSecurityGroupOn443:
    Type: AWS::EC2::SecurityGroupEgress
    DependsOn: NodeSecurityGroup
    Properties:
      Description: Allow the cluster control plane to communicate with pods running extension API servers on port 443
      GroupId: !Ref ClusterControlPlaneSecurityGroup
      DestinationSecurityGroupId: !Ref NodeSecurityGroup
      IpProtocol: tcp
      FromPort: 443
      ToPort: 443

  ClusterControlPlaneSecurityGroupIngress:
    Type: AWS::EC2::SecurityGroupIngress
    DependsOn: NodeSecurityGroup
    Properties:
      Description: Allow pods to communicate with the cluster API Server
      GroupId: !Ref ClusterControlPlaneSecurityGroup
      SourceSecurityGroupId: !Ref NodeSecurityGroup
      IpProtocol: tcp
      ToPort: 443
      FromPort: 443

  NodeGroup:
    Type: AWS::AutoScaling::AutoScalingGroup
    DependsOn: Cluster
    Properties:
      DesiredCapacity: !Ref NodeAutoScalingGroupDesiredCapacity
      LaunchConfigurationName: !Ref NodeLaunchConfig
      MinSize: !Ref NodeAutoScalingGroupDesiredCapacity
      MaxSize: !Ref NodeAutoScalingGroupDesiredCapacity
      VPCZoneIdentifier: !Ref Subnets
      Tags:
        - Key: Name
          Value: !Sub ${ClusterName}-node
          PropagateAtLaunch: true
        - Key: !Sub kubernetes.io/cluster/${ClusterName}
          Value: owned
          PropagateAtLaunch: true
    UpdatePolicy:
      AutoScalingRollingUpdate:
        MaxBatchSize: 1
        MinInstancesInService: !Ref NodeAutoScalingGroupDesiredCapacity
        PauseTime: PT5M

  NodeLaunchConfig:
    Type: AWS::AutoScaling::LaunchConfiguration
    Properties:
      AssociatePublicIpAddress: true
      IamInstanceProfile: !Ref NodeInstanceProfile
      ImageId: !Ref NodeImageIdSSMParam
      InstanceType: !Ref NodeInstanceType
      KeyName: !Ref KeyName
      SecurityGroups:
        - !Ref NodeSecurityGroup
      BlockDeviceMappings:
        - DeviceName: /dev/xvda
          Ebs:
            VolumeSize: !Ref NodeVolumeSize
            VolumeType: gp2
            DeleteOnTermination: true
      UserData:
        Fn::Base64:
          !Sub |
            #!/bin/bash
            set -o xtrace
            /etc/eks/bootstrap.sh "${ClusterName}"
            /opt/aws/bin/cfn-signal --exit-code $? \
                     --stack  ${AWS::StackName} \
                     --resource NodeGroup  \
                     --region ${AWS::Region}

Outputs:

  NodeInstanceRole:
    Description: The node instance role
    Value: !GetAtt NodeInstanceRole.Arn

  ClusterCertificate:
    Description: The cluster certificate
    Value: !GetAtt Cluster.CertificateAuthorityData

  ClusterEndpoint:
    Description: The cluster endpoint
    Value: !GetAtt Cluster.Endpoint